Chitosan／modified montmorillonite beads and adsorption Reactive Red 120

CARBON TECHNIQUES炭素技术2014年第4期第33卷2014№4Vol．33海藻酸钠/碳纳米管凝胶吸附水溶液Cu 2+的研究万洪善（连云港职业技术学院，江苏连云港222006）摘要：以1-乙基-3（3-二甲基氨基丙基）碳化二亚胺（EDC ）为相偶联剂，通过海藻酸钠（SAL)对碳纳米管（CNTs ）进行修饰和改性，制备海藻酸钠/碳纳米管凝胶,用于吸附水中微量Cu 2+。

考察了溶液pH 值、吸附时间、吸附剂量等因素对Cu 2+吸附性能的影响。

结果表明，利用海藻酸钠对多壁碳纳米管进行改性，提高了分散性、比表面积和孔径。

当pH 值为5.8时，吸附量随着吸附时间的增长而增大，80min 内达到了吸附平衡，且吸附率随着吸附剂量的增加而增大，表明海藻酸钠修饰后的碳纳米管是一种有效的水溶液中Cu 2+吸附剂。

关键词：多壁碳纳米管；海藻酸钠；Cu 2+；吸附中图分类号：O613.71；TB383文献标识码：A文章编号：1001-3741(2014)04-27-04Adsorption of copper ion （Ⅱ）in aqueous solution withSAL/MWCNT gelWan Hong -shan(Lianyungang Technical College,Jiangsu Lianyungang 222006，China)Abstract:Using 1-ethyl -3(3-dimethylamino-propyl)carbodiimide (EDC)as a coupling agent and multiwalled carbon tubes were modified by sodium alginate in order to prepare gel of SAL/MWCNT —COOH that was used to adsorb trace Cu 2+in artificial waste water ．The effects of pH value ，adsorption time and absorbent dosage on adsorption of Cu 2+were investigated ．The results show that the modification of multiwalled carbon nanotubes by using SAL can increase dispersion,specific surface area and aperture ．When pH value was 5.8,the adsorption rate increases with the increase of adsorbent dosage,and the adsorption attained equilibrium in 80min.The results showed that SAL/MWCNT —COOH is a kind of adsorbent for Cu 2+.Key words :Multi-walled carbon nanotubes;sodium;alginate;copperion;adsorption基金项目：2011年度高校科研成果产业化推进项目(JHB2011-77)，2012年连云港市农业攻关项目（CN1211），2013年连云港市工业攻关项目（CG1304-2）作者简介：万洪善，硕士，副教授，从事化学制药教学与科研工作，E -mail ：wanhs9799@ 。

Chemical Engineering Journal 169 (2011) 180–185Contents lists available at ScienceDirectChemical EngineeringJournalj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /c ejAmmonia-modified activated carbon for the adsorption of 2,4-dichlorophenolF.W.Shaarani,B.H.Hameed ∗School of Chemical Engineering,University of Science Malaysia,Engineering Campus,14300Nibong Tebal,Penang,Malaysiaa r t i c l e i n f o Article history:Received 5November 2010Received in revised form 27February 2011Accepted 1March 2011Keywords:AmmoniaActivated carbonOil palm empty fruit bunch 2,4-Dichlorophenol Adsorption Isotherm Kineticsa b s t r a c tIn this study,an oil palm empty fruit bunch-based activated carbon was modified using ammonia aque-ous solution.The effect of the chemical modification on the adsorption capacity of modified activated carbon (MAC)for 2,4-dichlorophenol (2,4-DCP)adsorption was investigated.The monolayer adsorption capacity of MAC was 285.71mg/g at 30◦C.Adsorption isotherm fitting revealed that Langmuir model was applicable for the MAC.The adsorption kinetics of 2,4-DCP onto MAC was described by the pseudo-second-order kinetic model.The surface modification of the activated carbon using ammonia was shown to be able to increase its adsorption capacity for 2,4-DCP.© 2011 Elsevier B.V. All rights reserved.1.IntroductionIn recent years,increasing concern over pollution of water courses arising from different anthropogenic activities has resulted in growing demand of activated carbons [1].They have proved to be effective for the removal of a wide variety of organic and inorganic pollutants dissolved in aqueous media,or from gaseous environ-ments [2].However,activated carbon is expensive which limits its large scale application [3].A potential method to reduce its cost is to produce activated carbon from low-cost materials such as agri-cultural by-products,which has attracted an increasing research interest in recent years [4].The excellent performances of activated carbons is well known to be closely related to the well developed porous structures,large surface area and a wide spectrum of surface functional groups.It is an established fact that the activated carbon surface can display acidic,basic and/or neutral characteristics depending on the pres-ence of surface functional groups [5].Thus,these days more studies have focused on how to modify as well as to characterize the sur-face functional groups of carbon materials in order to improve or enhance their affinities towards certain contaminants [3,6,7].The heteroatoms on the surface of activated carbon took sig-nificant role on its application.The heteroatoms of porous carbon surface mainly contained oxygen,nitrogen,hydrogen,halogen,etc.,which bonded to the edges of the carbon layers and gov-erned the surface chemistry of activated carbon [8].Among these∗Corresponding author.Tel.:+6045996422;fax:+6045941013.E-mail address:chbassim@m.my (B.H.Hameed).heteroatoms,the oxygen-containing functional groups as well as nitrogen-containing functional groups were the widely recognized and the most common species formed on the surface of carbons.The presence of nitrogen-containing functional groups was claimed to increase the basicity of activated carbon surface and thus increased the adsorption of acidic agents such as phenolic deriva-tives.Practically,nitrogen is introduced into structure of activated carbon according to several procedures including treatment with ammonia or urea [9,10].Adsorption of phenolic derivatives on activated carbons has been intensively investigated [11],but relatively less work is reported related to modified carbons [12].In this work,oil palm empty fruit bunch-based activated carbon was treated with ammo-nia solution to modify its surface functional groups.The adsorption performance of the modified activated carbon on 2,4-DCP was then evaluated.2.Materials and methods 2.1.2,4-Dichlorophenol2,4-Dichlorophenol (2,4-DCP)of analytical reagent grade (Merck)was used as an adsorbate in this study.2,4-DCP has a chem-ical formula of C 6H 3Cl 2OH,with a molecular weight of 163.0g/mol.2.2.Preparation of activated carbonOil palm empty fruit bunch (EFB)used for preparation of acti-vated carbon was obtained from United Oil Palm Industries Sdn Bhd,Malaysia.The procedure used to prepare the activated car-1385-8947/$–see front matter © 2011 Elsevier B.V. All rights reserved.doi:10.1016/j.cej.2011.03.002F.W.Shaarani,B.H.Hameed /Chemical Engineering Journal 169 (2011) 180–185181400.010001500200030004000.05.006.08.010.012.014.016.018.020.022.00%TMACPAC3399.931594.17976.973850.993737.022360.861542.431052.87828.41790.89607.06Wavenumber (cm -1)Fig.1.FTIR spectrum for PAC and MAC.bon was referred to our previous work [13].The precursor was washed,sun dried,and crushed to particle size of 1–2mm.The pre-treated precursor was then soaked with 20wt%of phosphoric acid solution with an impregnation ratio of 16:1(acid:precursor).Sub-sequently the precursor was filtered from phosphoric acid solution and then was dehydrated in the oven at 105◦C for 24h.The impreg-nated precursor was then loaded in a stainless steel vertical tubular reactor placed in a tube furnace.It was then heated at a rate of 10◦C/min from room temperature to 450◦C under purified nitro-gen (99.995%)flow of 150cm 3/min.Activation took place for 2h before it was cooled down to room temperature.The final prod-uct was then washed with 0.1M hydrochloric acid and hot distilled water until the pH of the washing solution reached 6–7,then dried in the oven at 105◦C for 24h and finally kept in an airtight con-tainer for further use.This sample was known as pristine activated carbon (PAC).2.3.Modification of activated carbonAn amount of 4g of the PAC was immersed in 150mL of 10wt %ammonia solution (analytical reagent grade)and left for 48h at room temperature.After this time the treated activated car-bons were separated from liquid phase by mean of filtration and then dried at 105◦C for 24h.The chemically treated activated car-bons were stored in a desiccator to prevent moisture build up.The obtained sample was called modified activated carbon (MAC).2.4.FTIR of activated carbonSince MAC was modified via chemical treatment,changes in surface functional groups on MAC from PAC needed to be stud-ied.The surface functional groups of both the PAC and MAC were detected by Fourier Transform Infrared (FTIR)spectroscope (FTIR-2000,Perkin Elmer).The spectra were recorded from 4000to 400cm −1.2.5.Batch equilibrium studiesAdsorption was performed in a set of 250mL-Erlenmeyer flasks where 200mL of 2,4-DCP solutions with various initial concentra-tions (25–250mg/L)were placed.Equal mass of activated carbon (0.2g)was added to each flask and kept in an isothermal shaker (30,40or 50◦C)at 130rpm for 24h to reach equilibrium.The pH of the solution was kept original without any adjustment.Aque-ous samples were taken from the solution and the concentrationswere analyzed.All samples were filtered prior to analysis in order to minimize interference of the carbon fines with the analysis.Each experiment was duplicated under identical conditions.The concen-trations of 2,4-DCP before and after adsorption were determined using a double beam UV–vis spectrophotometer (Shimadzu,Japan)at 280nm.The amount adsorbed at equilibrium,q e (mg/g),was calculated by:q e =(C 0−C e )V(1)where C 0and C e (mg/L)are the liquid-phase concentrations of 2,4-DCP at initial and equilibrium,respectively.V (L)is the volume of the solution and W (g)is the mass of dry adsorbent used.2.6.Effect of solution pHThe effect of solution pH on the 2,4-DCP removal was stud-ied at different initial pH (2–12).The pH was adjusted using 0.1M HCl and/or 0.1M NaOH and was measured using pH meter (Model Ecoscan,EUTECH Instruments,Singapore).The 2,4-DCP initial con-centration was fixed at 100mg/L,with activated carbon dosage of 0.2g/100mL and temperature of 30◦C.3.Results and discussion3.1.Surface chemistry of activated carbonsFig.1shows FTIR spectra of the PAC and the MAC.Several broad peaks were detected on the spectra of both activated car-bons at bandwidths around 3850–3300which could be assigned to O–H stretching vibration of hydroxyl functional groups.On the other hand,the spectra of these samples show some differences.For example,the spectrum of the PAC exhibits one strong peak at 1594cm −1associated with C–O group whereas peak at 976cm −1was attributed to P–O–C carbons asymmetric stretching,interac-tion between aromatic ring vibration and P–C (aromatic)stretching and/or symmetrical stretching of PO 2and PO 3in phosphate–carbon complexes.Therefore,P-containing carbonaceous structures like acid phosphates and polyphosphates are formed in the samples carbonized in the presence of H 3PO 4[14].MAC displays presence of one strong peak at 2360cm −1which corresponds to the C C stretching vibrations in alkyne groups.In addition the spectrum of MAC exhibits the appearance of new bands related to N-containing species at 1542cm −1(cyclic amides [7])and 1052cm −1(C–N of the amine group [7])implying that the use of ammonia modification182 F.W.Shaarani,B.H.Hameed/Chemical Engineering Journal169 (2011) 180–185Fig.2.Effect of solution temperature on2,4-DCP uptake on MAC at various initial concentrations.produced new nitrogen surface complexes.The results were com-parable with the work done by Przepiórski[15]which reported that more basic groups such as cyclic amides and amines groups were produced by ammonia-treated activated carbons.3.2.Effect of temperatureThe temperature has two major effects on the adsorption pro-cess.Increasing the temperature is known to increase the rate of diffusion of the adsorbate molecules across the external boundary layer and in the internal pores of the adsorbent particles as a result of the reduced viscosity of the solution.In addition,changing the temperature alters the equilibrium capacity of the adsorbent for a particular adsorbate[16].The effect of temperature on adsorption of2,4-DCP on the MAC was investigated by varying the adsorption temperature at30,40 and50◦C.Fig.2shows the plot of adsorption capacity versus ini-tial2,4-DCP concentrations(25–250mg/L)at the three different temperatures.The adsorption of2,4-DCP on the MAC was found to gradually increase when the temperature was increased from 30to50◦C for all initial concentrations studied(25–250mg/L).In addition,an increase in temperature from30to50◦C increased the MAC monolayer adsorption capacities from285.71to312.50mg/g (Table1).This phenomenon indicates that the adsorption process is endothermic in nature.This may be due to an increasing number of molecules which may also acquire sufficient energy to undergo an interaction with active sites at the surface.Furthermore,increas-ing temperature may produce a swelling effect within the internal structure of the activated carbons enabling large dyes to penetrate further as being reported byÖzdemir et al.[17].3.3.Effect of solution pHFig.3shows the effect of solution pH on the removal of2,4-DCP on the MAC.It was observed that the2,4-DCP removal was highly dependent on the pH of the solution which affected the sur-face charge of the activated carbon and the degree of ionization of the adsorbate.It was found that an increase in the solution pH led to a decrease in the2,4-DCP removal efficiency.The highest per-cent removal was achieved at pH2,with2,4-DCP uptake as high as97.24%whereas the lowest percent removal was recorded at pH12with only66.39%.2,4-DCP acts as a weak acid,the dissocia-tion of hydrogen ion from the phenol molecules strongly depended on the pH level of solution.More protons were available in acidic solution,thus increasing electrostatic attraction between molecu-lar species of2,4-DCP and the positively charged adsorptionsites,20406080100pH%RemovalFig.3.Effect of solution pH on2,4-DCP removal on MAC at30◦C(2,4-DCP initial concentration=100mg/L).thus causing an increase in the adsorption of2,4-DCP.As the pH of the solution increased,2,4-DCP dissociated,forming chlorophe-nolate anions while the surface functional groups on the activated carbons were either neutral or negatively charged.As a result of the electrostatic repulsion between the identical charges it then low-ered the adsorption capacity.This observation is similar with the trend reported by Hameed et al.[18]and Gao and Wang[19].3.4.Adsorption of2,4-DCPThe linear form of Langmuir isotherm[20]equation is given as: C eq e=1Q0C e+1Q0b(2) where C e is the equilibrium concentration of the adsorbate(mg/L), q e is the amount of adsorbate adsorbed per unit mass of adsor-bent(mg/g),Q0and b are Langmuir constants related to adsorption capacity and rate of adsorption,respectively.When C e/q e was plot-ted against C e,a straight line was obtained.Q0was calculated from the slope whereas b was found from the intercept(Fig.4).The linear form of Freundlich isotherm[21]is given by the fol-lowing equation:log q e=1n log C e+log K F(3) where C e(mg/L)is the equilibrium concentration of the adsorbate, q e(mg/g)is the amount of adsorbate adsorbed per unit mass of adsorbent,K F(mg/g(L/mg)1/n)and n are Freundlich constants with n giving an indication of how favorable the adsorption process.K F is the adsorption capacity of the adsorbent which can be defined as the adsorption or distribution coefficient and representsthe0.000.020.040.060.080.10252015105C e (mg/L)Ce/qe(g/L)ngmuir adsorption isotherm of2,4-DCP onto MAC at30◦C.F.W.Shaarani,B.H.Hameed /Chemical Engineering Journal 169 (2011) 180–185183Table 1Langmuir and Freundlich isotherm model constants and correlation coefficients.Temperature (◦C)Isotherm Langmuir Freundlich Q 0(mg/g)K L (L/mg)R 2K F (mg/g(L/mg)1/n )1/n R 230285.710.2170.9949.2720.5850.9140303.030.2700.9958.8980.6250.9350312.504.0000.99319.5950.6200.93quantity of 2,4-DCP adsorbed onto activated carbon for a unit equi-librium concentration.The slope of 1/n ranging between 0and 1is a measure of adsorption intensity or surface heterogeneity,becom-ing more heterogeneous as its value gets closer to zero.A value for 1/n below one indicates a normal Langmuir isotherm while 1/n above one is indicative of cooperative adsorption.The plot of log q e versus log C e (Fig.5)gave a straight line with slope of 1/n whereas K F was calculated from the intercept value.The Langmuir and Freundlich adsorption constants evaluated from the isotherms with the correlation coefficients for MAC are listed in Table 1.According to the data tabulated in Table 1,adsorp-tion of 2,4-DCP on MAC was found to follow the Langmuir isotherm model since the correlation coefficient,R 2values obtained for Langmuir isotherm yielded the best fit (close to unity)at all temper-atures,in comparison to Freundlich isotherm where the correlation coefficient,R 2values obtained were only between 0.91and 0.93.Similar trend was observed for PAC where the Langmuir isotherm also gave the best fit for the adsorption of 2,4-DCP at all range of temperatures studied with R 2values of 0.99[13].From Fre-undlich isotherm model,the values of 1/n attained were <1.This specified a normal Langmuir isotherm.The result indicated the homogeneous nature of the surfaces of the activated carbon,i.e.,each 2,4-DCP molecule/carbon adsorption had equal adsorption activation energy.The results also demonstrated the formation of monolayer coverage of 2,4-DCP molecule at the outer surfaces of MAC.The same trend was procured by several researchers [22–24]on the adsorption of 2,4-DCP on various adsorbents where the data gave a better fit in Langmuir isotherm model in comparison to Freundlich isotherm model.The surface modification on the oil palm empty fruit bunch-based activated carbon using ammonia solution was shown to be able to increase its adsorption capacity on 2,4-DCP,from 232.56[13]to 285.71mg/g (22.86%higher)at 30◦C.This enhancement was due to the electrostatic attraction between 2,4-DCP and the sur-face of MAC.2,4-DCP is predominantly present in anionic form.The chloride (–Cl)ion on the benzene ring,which increased the acidic character was responsible for forming anion on the oxygen atom of0.001.002.003.001.51.00.50.0-0.5Log C eL o g q eFig.5.Freundlich adsorption isotherm of 2,4-DCP onto MAC at 30◦C.the –OH group and also had a strong affinity for activated carbon surfaces.The basic surface functional groups created by nitrogen-incorporation (via ammonia treatment)rendered the carbon more basic;and created a surface that was more positively charged.As a result of electrostatic attractions between the negative charge on 2,4-DCP compound and positive charge of modified carbon surface,hence the uptake of 2,4-DCP increased.This phenomenon is similar to previous work reported by Deng et al.[25]on removal of pen-tachlorophenol and 2,4-dichlorophenoxyacetic acid from aqueous solution by an aminated biosorbent.They reported that the surface charge on the aminated biomass played an important role in the sorption of anionic pollutants.Table 2lists the comparison of the maximum monolayer adsorption capacity of various types of chlorophenols on various adsorbents.The adsorption capacity of MAC for 2,4-DCP was rela-tively high and comparable to some previous works reported in the literature.3.5.Kinetic studiesA linear form of pseudo-first-order model was described by Lagergren and Svenska [30]in the form:log(q e −q t )=log q e −k 12.303t (4)where q e and q t refer to the amount of 2,4-DCP adsorbed (mg/g)at equilibrium and at any time,t (h),respectively,and k 1is the equi-librium rate constant of pseudo-first order sorption (1/h ).Values of k 1were obtained from the slopes of the linear plots of log(q e −q t )versus t ,as shown in Fig.6.The parameters of pseudo-first-order kinetics model for MAC are summarized in Table 3.The pseudo-second-order equation [31]is expressed as:t q t =1k 2q 2e+ 1q et (5)where q e and q t are the adsorption capacities at equilibrium and at time t ,respectively (mg/g)and k 2is the rate constant of pseudo-second-order sorption (g/mg h).By plotting t /q t versus t (Fig.7),q e and k 2can be determined from slope and intercept.Table 3sum--112345t (h)l o g (q e - q t )Fig.6.Pseudo-first-order kinetics for adsorption of 2,4-DCP on MAC at 30◦C.184 F.W.Shaarani,B.H.Hameed /Chemical Engineering Journal 169 (2011) 180–185Table 2Comparison of maximum monolayer adsorption capacity of various chlorophenols on various adsorbents.AdsorbentAdsorbateMaximum monolayer adsorption capacity (mg/g)References MAC 2,4-Dichlorophenol 285.71This work PAC2,4-Dichlorophenol 232.56[13]Maize cob carbon2,4-Dichlorophenol 17.94[22]Molecularly imprinted polymer (MIP)2,4-Dichlorophenol 183.80[23]Punica granatum (Pomegranate)peel 2,4-Dichlorophenol 75.80[24]Palm pith carbon2,4-Dichlorophenol 19.16[26]Oil palm empty fruit bunch 2,4-Dichlorophenol 27.25[27]Activated carbon fiber2,4-Dichlorophenol 372.00[28]Rattan sawdust activated carbon4-Chlorophenol188.68[29]Table 3Comparison of the pseudo-first-order model and pseudo-second-order model for adsorption of 2,4-DCP on MAC at 30◦C.Initial 2,4-DCP concentration (mg/L)q e ,exp (mg/g)Pseudo-first-order kinetic model Pseudo-second-order kinetic model q e ,cal (mg/g)k 1(1/h)R 2 q (%)q e ,cal (mg/g)k 2(g/mg h)R 2 q (%)2525.14 2.49 1.0840.9834.06025.19 1.3130.990.0775051.1417.17 1.3310.9825.11052.360.1660.990.896100101.9125.820.8150.9828.219100.000.1110.990.707150147.3253.730.7960.9924.012144.930.0480.990.613200195.07100.880.6950.9918.251188.680.0220.99 1.239250233.35119.210.4100.9918.488196.080.0240.996.0370.000.020.040.060.080.10t (h)t /q t (h r .g /m g )Fig.7.Pseudo-second-order kinetics for adsorption of 2,4-DCP on MAC at 30◦C.marizes the parameters of pseudo-second-order kinetics model for MAC.It can be seen from Table 3,that the correlation coefficients,R 2obtained from the two kinetic models were greater than 0.9for all 2,4-DCP concentrations.The suitability of the model to describe the adsorption kinetics was further justified based on the normalized standard deviation value, q (%),which is defined as:q (%)=[(q exp −q cal )/q exp ]2N −1×100(6)where N is the number of data points,q exp and q cal (mg/g)are the experimental and calculated adsorption capacity,respectively.The lower the value of q the better the model fits.It is clearly shown in Table 3,that the pseudo-second-order kinetic model yielded the lower q values.This is in agreement with the R 2values obtained earlier and proves that the adsorption of 2,4-DCP onto the MAC could be best described by the pseudo-second-order kinetic model.The kinetic data obtained for the adsorption of 2,4-DCP using PAC [13]was also found to follow the pseudo-second-order kinetic model.These results proved that the chemical treatment on the activated carbon did not change its adsorption mechanism where the adsorption of 2,4-DCP on both the activated carbons was best described by the pseudo-second-order kinetic model.The results obtained were in accordance with the previous works carried out on adsorption of phenolic compounds on thebanana peel [32]and substituted phenols on activated carbon fibers [33].4.ConclusionThe present investigation showed that the use of ammonia treat-ment to modify the oil palm empty fruit bunch activated carbon could enhance its adsorption capacity for 2,4-DCP.The equilibrium data for MAC were best represented by the Langmuir isotherm.The surface modification of the activated carbon using ammonia was shown to be able to increase its adsorption capacity for 2,4-DCP from 232.56[13]to 285.71mg/g (22.86%higher).This was due to the basic surface functional groups created by nitrogen-incorporation (via ammonia treatment)which rendered the carbon more basic;and created a surface that was more positively charged and thus improved the activated carbon uptake.The adsorption kinetics was found to follow closely the pseudo second-order kinetic model.AcknowledgementThe authors acknowledge the research grant provided by the Universiti Sains Malaysia under the Research University (RU)Scheme (Project No.1001/PJKIMIA/814003).References[1]J.de Celis,N.E.Amadeo,A.L.Cukierman,In situ modification of activated carbonsdeveloped from a native invasive wood on removal of trace toxic metals from 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山东科学ＳＨＡＮＤＯＮＧＳＣＩＥＮＣＥ第３７卷第１期２０２４年２月出版Ｖｏｌ.３７Ｎｏ.１Ｆｅｂ.２０２４收稿日期:２０２３￣０４￣１４作者简介:潘翔宇(１９９８ )ꎬ男ꎬ硕士研究生ꎬ研究方向为功能化色谱填料的研究ꎮＥ￣ｍａｉｌ:１３４２４７８５０９＠ｑｑ.ｃｏｍ∗通信作者ꎬ靳钊ꎬ男ꎬ高级工程师ꎬ研究方向为功能材料的制备ꎮＥ￣ｍａｉｌ:ｊｉｎｚｈａｏ＠ｑｕｓｔ.ｅｄｕ.ｃｎ乙二胺￣Ｎ￣丙基改性硅胶的可控键合制备及其在银杏酸脱除中的应用研究潘翔宇ꎬ靳钊∗ꎬ关彤ꎬ陈贝怡(青岛科技大学高分子科学与工程学院ꎬ山东青岛２６６０４５)摘要:优化了乙二胺￣Ｎ￣丙基键合硅胶(ＰＳＡ)键合量可控的制备工艺ꎬ考察了ＰＳＡ制备的批次重复性ꎬ并进行ＰＳＡ制备的中试放大实验ꎮ采用红外光谱㊁元素分析及电位滴定法对所制备的ＰＳＡ进行性能评价ꎬ结果表明:在３４６０ｃｍ－１处出现了Ｎ Ｈ伸缩振动峰ꎬ在２９６０ｃｍ－１和２８６０ｃｍ－１处出现了 ＣＨ的不对称和对称伸缩振动峰ꎬ７０８ｃｍ－１处出现了 ＮＨ２的变形振动吸收峰ꎬ表明乙二胺￣Ｎ￣丙基成功接枝到硅胶表面ꎻ随着制备体系中硅烷化试剂比例的增加ꎬ碳㊁氮和氢元素的含量以及电位滴定法得到的离子交换容量均呈现上升趋势ꎬ说明乙二胺￣Ｎ￣丙基官能团的键合量逐渐增加ꎮ将制备的ＰＳＡ填充成分离纯化小柱ꎬ考察了不同键合量ＰＳＡ对银杏叶提取物中银杏酸的脱除效率ꎬ结果表明:ＰＳＡ对银杏酸有强吸附能力ꎬ可应用于银杏叶提取物中银杏酸的脱除ꎬ２＃㊁３＃㊁４＃和５＃ＰＳＡ分离纯化柱的最大上样体积分别为２１㊁２２㊁２３㊁２４ｍＬꎬ且脱除效率随乙二胺￣Ｎ￣丙基键合量的增加而升高ꎮ关键词:乙二胺￣Ｎ￣丙基改性硅胶ꎻ键合量ꎻ银杏酸脱除中图分类号:Ｏ６５８㊀㊀㊀文献标志码:Ａ㊀㊀㊀文章编号:１００２￣４０２６(２０２４)０１￣００５１￣０８开放科学(资源服务)标志码(ＯＳＩＤ):Ｃｏｎｔｒｏｌｌａｂｌｅｂｏｎｄｉｎｇｐｒｅｐａｒａｔｉｏｎｏｆｅｔｈｙｌｅｎｅｄｉａｍｉｎｅ￣Ｎ￣ｐｒｏｐｙｌｍｏｄｉｆｉｅｄｓｉｌｉｃａｇｅｌａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｉｎｇｉｎｋｇｏｌｉｃａｃｉｄｒｅｍｏｖａｌＰＡＮＸｉａｎｇｙｕꎬＪＩＮＺｈａｏ∗ꎬＧＵＡＮＴｏｎｇꎬＣＨＥＮＢｅｉｙｉ(ＳｃｈｏｏｌｏｆＰｏｌｙｍｅｒＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇꎬＱｉｎｇｄａｏＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙꎬＱｉｎｇｄａｏ２６６０４５ꎬＣｈｉｎａ)ＡｂｓｔｒａｃｔʒＩｎｔｈｉｓｐａｐｅｒꎬｔｈｅｐｒｅｐａｒａｔｉｏｎｐｒｏｃｅｓｓｏｆＮ￣ｐｒｏｐｙｌｅｔｈｙｌｅｎｅｄｉａｍｉｎｅｂｏｎｄｅｄｓｉｌｉｃａｇｅｌ(ＰＳＡ)ｗｉｔｈｃｏｎｔｒｏｌｌａｂｌｅｂｏｎｄｉｎｇａｍｏｕｎｔｗａｓｏｐｔｉｍｉｚｅｄꎻｔｈｅｂａｔｃｈｒｅｐｅａｔａｂｉｌｉｔｙｏｆＰＳＡｐｒｅｐａｒａｔｉｏｎｗａｓｅｘａｍｉｎｅｄꎻａｎｄｔｈｅｐｉｌｏｔｓｃａｌｅ￣ｕｐｅｘｐｅｒｉｍｅｎｔｏｆＰＳＡｐｒｅｐａｒａｔｉｏｎｗａｓｃｏｎｄｕｃｔｅｄ.ＴｈｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅＰＳＡｗｅｒｅｉｎｖｅｓｔｉｇａｔｅｄｂｙｉｎｆｒａｒｅｄｓｐｅｃｔｒｏｓｃｏｐｙꎬｅｌｅｍｅｎｔａｌａｎａｌｙｓｉｓꎬａｎｄｐｏｔｅｎｔｉｏｍｅｔｒｉｃｔｉｔｒａｔｉｏｎ.ＴｈｅｒｅｓｕｌｔｓｓｈｏｗｅｄｔｈａｔＮ Ｈｓｔｒｅｔｃｈｉｎｇｖｉｂｒａｔｉｏｎｐｅａｋｓａｐｐｅａｒｅｄａｔ３４６０ｃｍ－１ꎬａｓｙｍｍｅｔｒｉｃａｎｄｓｙｍｍｅｔｒｉｃｓｔｒｅｔｃｈｉｎｇｖｉｂｒａｔｉｏｎｐｅａｋｓｏｆ ＣＨａｐｐｅａｒｅｄａｔ２９６０ｃｍ－１ａｎｄ２８６０ｃｍ－１ꎬａｎｄｄｅｆｏｒｍａｔｉｏｎｖｉｂｒａｔｉｏｎａｂｓｏｒｐｔｉｏｎｐｅａｋｓｏｆ ＮＨ２ａｐｐｅａｒｅｄａｔ７０８ｃｍ－１ꎬｉｎｄｉｃａｔｉｎｇｔｈａｔＮ￣ｐｒｏｐｙｌｅｔｈｙｌｅｎｅｄｉａｍｉｎｅｗａｓｓｕｃｃｅｓｓｆｕｌｌｙｇｒａｆｔｅｄｏｎｔｏｔｈｅｓｕｒｆａｃｅｏｆｓｉｌｉｃａｇｅｌ.Ｆｕｒｔｈｅｒｍｏｒｅꎬｗｉｔｈｔｈｅｉｎｃｒｅａｓｉｎｇｐｒｏｐｏｒｔｉｏｎｏｆｓｉｌａｎｅｒｅａｇｅｎｔｉｎｔｈｅｐｒｅｐａｒａｔｉｏｎｓｙｓｔｅｍꎬｔｈｅｃｏｎｔｅｎｔｏｆｃａｒｂｏｎꎬｎｉｔｒｏｇｅｎꎬａｎｄｈｙｄｒｏｇｅｎｅｌｅｍｅｎｔｓａｎｄｔｈｅｉｏｎｅｘｃｈａｎｇｅｃａｐａｃｉｔｙｏｂｔａｉｎｅｄｂｙｐｏｔｅｎｔｉｏｍｅｔｒｉｃｔｉｔｒａｔｉｏｎｓｈｏｗｅｄａｎｕｐｗａｒｄｔｒｅｎｄꎬｉｎｄｉｃａｔｉｎｇｔｈａｔｔｈｅｂｏｎｄｉｎｇａｍｏｕｎｔｏｆｅｔｈｙｌｅｎｅｄｉａｍｉｎｅ￣Ｎ￣ｐｒｏｐｙｌｆｕｎｃｔｉｏｎａｌｇｒｏｕｐｇｒａｄｕａｌｌｙｉｎｃｒｅａｓｅｄ.ＭｏｒｅｏｖｅｒꎬｔｈｅｐｒｅｐａｒｅｄＰＳＡｐａｃｋｉｎｇｃｏｍｐｏｎｅｎｔｗａｓｓｅｐａｒａｔｅｄｆｒｏｍｔｈｅｐｕｒｉｆｉｃａｔｉｏｎｃｏｌｕｍｎꎬａｎｄｔｈｅｒｅｍｏｖａｌｅｆｆｉｃｉｅｎｃｙｏｆｇｉｎｋｇｏｌｉｃａｃｉｄｆｒｏｍｔｈｅｅｘｔｒａｃｔｏｆｇｉｎｋｇｏｂｉｌｏｂａｌｅａｖｅｓｕｓｉｎｇＰＳＡｗｉｔｈｄｉｆｆｅｒｅｎｔｂｏｎｄｉｎｇａｍｏｕｎｔｓｗａｓｉｎｖｅｓｔｉｇａｔｅｄ.ＴｈｅｒｅｓｕｌｔｓｓｈｏｗｅｄｔｈａｔＰＳＡｈａｄａｓｔｒｏｎｇａｄｓｏｒｐｔｉｏｎｃａｐａｃｉｔｙｆｏｒｇｉｎｋｇｏｌｉｃａｃｉｄａｎｄｃｏｕｌｄｂｅｕｓｅｄｔｏｒｅｍｏｖｅｇｉｎｋｇｏｌｉｃａｃｉｄｆｒｏｍｔｈｅｅｘｔｒａｃｔｏｆｇｉｎｋｇｏｂｉｌｏｂａｌｅａｖｅｓꎬｔｈｅｍａｘｉｍｕｍｓａｍｐｌｅｌｏａｄｉｎｇｖｏｌｕｍｅｓｆｏｒＰＳＡｓｅｐａｒａｔｉｏｎａｎｄｐｕｒｉｆｉｃａｔｉｏｎｃｏｌｕｍｎｓ２＃ꎬ３＃ꎬ４＃ꎬａｎｄ５＃ａｒｅ２１ꎬ２２ꎬ２３ꎬ２４ｍＬꎬｒｅｓｐｅｃｔｉｖｅｌｙ.Ｉｎａｄｄｉｔｉｏｎꎬｔｈｅｒｅｍｏｖａｌｅｆｆｉｃｉｅｎｃｙｗａｓｆｏｕｎｄｔｏｉｎｃｒｅａｓｅｗｉｔｈｔｈｅｉｎｃｒｅａｓｉｎｇａｍｏｕｎｔｏｆｅｔｈｙｌｅｎｅｄｉａｍｉｎｅ￣Ｎ￣ｐｒｏｐｙｌｂｏｎｄｉｎｇ.Ｋｅｙｗｏｒｄｓʒｅｔｈｙｌｅｎｅｄｉａｍｉｎｅ￣Ｎ￣ｐｒｏｐｙｌｍｏｄｉｆｉｅｄｓｉｌｉｃａｇｅｌꎻｂｏｎｄｉｎｇｑｕａｎｔｉｔｙꎻｇｉｎｋｇｏａｃｉｄｒｅｍｏｖａｌ㊀㊀胺类硅胶材料由于强吸附性能已经成为人们研究的热门课题[１￣４]ꎬ乙二胺￣Ｎ￣丙基键合硅胶(ＰＳＡ)是目前被广泛应用的一种胺基键合硅胶ꎬ因ＰＳＡ具有两个胺基且存在仲胺ꎬ通过弱阴离子交换和正相保留作用ꎬ其具有较大的离子交换容量[５]ꎮ李来明等[６]采用非均相氨化法合成硅胶微球ꎬ制备了氨丙基和乙二胺￣Ｎ￣丙基两种胺基键合硅胶并评价了其对甲苯磺酸吸附的吸附量ꎮＡｇｕａｄｏ等[７]制备了氨丙基㊁乙二胺￣Ｎ￣丙基㊁二乙烯三胺基丙基功能化介孔硅胶ＳＢＡ￣１５材料ꎬ可用于污水中重金属Ｃｕ２＋等重金属离子的吸附ꎮ王军等[８]以ＰＳＡ和十八烷基键合硅胶为净化材料去除样品中的干扰物质ꎬ建立了一种ＱｕＥＣｈＥＲＳ－气相色谱－质谱法检测酥油中的８种有机磷农药残留ꎮ蒋明明等[９]建立了一种基于ＰＳＡ和多壁碳纳米管通过超高效液相色谱－质谱法测定普洱茶中３种手性杀菌剂农药残留的分析方法ꎮＭａ等[１０]通过ＰＳＡ去除番茄㊁甜椒和甜食中的有机酸㊁一些糖类和极性色素ꎮ然而ꎬ目前同一厂家的商品化ＰＳＡ离子交换容量通常为固定值ꎬ针对不同有害物质的脱除需要不同离子交换容量的ＰＳＡ来实现ꎬ对ＰＳＡ的应用效果及应用领域产生了一定的限制作用ꎮ目前ＰＳＡ生产处于实验室阶段ꎬ中试批量生产ＰＳＡ难度大ꎬ无法满足ＰＳＡ的实际应用需求ꎮ因此ꎬ开发乙二胺￣Ｎ￣丙基键合量可控的ＰＳＡ制备工艺ꎬ并进行中试放大实验生产批次稳定性高㊁离子交换容量可选的ＰＳＡ具有重要的应用价值ꎮ银杏叶提取物中含有银杏黄酮和银杏内酯等药用活性成分[１１]ꎬ但其中也含有具有较强毒副作用[１２￣１５]的银杏酸[１６￣１７]ꎮ«中国药典»[１８]中规定银杏叶提取物中银杏酸的质量分数不得超过５ｍｇ/ｋｇꎬ其中白果新酸为银杏酸中的主要成分ꎬ白果新酸具有抗氧化㊁抗血小板聚集及改善记忆㊁提高机体免疫功能等药理作用ꎬ可用于防治农业病虫害㊁抑制痤疮致病菌等ꎮ目前通常使用大孔树脂脱除银杏酸ꎬ辛云海[１９]用Ｄ９１８阴离子交换树脂对银杏提取物中银杏酸进行脱除ꎬ但大孔树脂存在处理步骤繁琐㊁成本较高且会出现破碎的问题ꎮ硅胶作为一种稳定的无机材料具有高机械稳定性ꎬ乙二胺￣Ｎ￣丙基官能团具有双氨基结构ꎬ与银杏酸间可产生强吸附作用力ꎬ因此ＰＳＡ在银杏酸脱除中具有理想的应用前景ꎮ本文探讨了ＰＳＡ制备工艺中乙二胺￣Ｎ￣丙基硅烷化试剂和三甲基氯硅烷两个关键参数的用量与ＰＳＡ键合量的关系ꎬ实现ＰＳＡ离子交换容量可调控的制备工艺要求ꎬ并对优化的制备工艺进行中试放大实验ꎬ通过离子交换容量㊁红外光谱和元素分析结果对制备重复性进行表征ꎬ保证制备工艺的批次稳定性ꎮ将制备的ＰＳＡ填充成分离纯化小柱ꎬ应用于银杏叶提取物中有害物质银杏酸的脱除ꎮ采用«中国药典»中规定的高效液相色谱法对银杏酸含量进行定量分析ꎬ考察了不同离子交换容量的ＰＳＡ对银杏酸的脱除效率ꎬ评价ＰＳＡ在银杏酸脱除方面的应用前景ꎮ１㊀实验部分１.１㊀试剂与仪器硅胶(２３０~４００目)ꎬ青岛美高集团有限公司ꎻ乙二胺￣Ｎ￣丙基三甲氧基硅烷(纯度ȡ９５％)ꎬ上海吉至生化科技有限公司ꎻ三甲基氯硅烷(纯度ȡ９９.９９％)ꎬ上海阿拉丁生化科技股份有限公司ꎻ白果新酸(标准品ꎬ纯度ȡ９８％)ꎬ四川维克奇生物科技有限公司ꎻ浓盐酸㊁甲苯㊁４Ａ型分子筛㊁二氯甲烷㊁三氟乙酸㊁磷酸㊁乙醇和甲醇ꎬＡＲꎬ国药集团化学试剂有限公司ꎻ甲醇ꎬ色谱纯ꎬ德国默克股份公司ꎻ乙腈ꎬ色谱纯ꎬ天津康科德科技有限公司ꎮＷａｔｅｒｓ２６９５高效液相色谱仪配置Ｗａｔｅｒｓ２４８７双波长检测器ꎬ美国Ｗａｔｅｒｓ公司ꎻＶａｒｉｏＥＬⅢ型元素分析仪ꎬ德国Ｅｌｅｍｅｎｔａｒ公司ꎻＮｉｃｏｌｅｔ６７００ＦＴＩＲＳｐｅｃｔｏｒｍｅｔｅｒ型傅里叶变换红外分析光谱仪ꎬ美国Ｔｈｅｒｍｏ公司ꎻＲ￣１００１ＶＮ型旋转蒸发仪ꎬ郑州长城科工贸有限公司ꎻ高精度电位滴定仪ꎬ北京海光仪器有限公司ꎻ马弗炉ꎬ济南精锐分析仪器有限公司ꎻ反应釜ꎬ南京科尔仪器设备有限公司ꎻ电热鼓风烘箱ꎬ上海精宏实验设备有限公司ꎻ真空干燥箱ꎬ上海一恒科学仪器有限公司ꎮ１.２㊀ＰＳＡ的制备１.２.１㊀ＰＳＡ制备工艺优化将硅胶置于４５０ħ马弗炉中活化６ｈꎬ得到活化硅胶ꎮ取活化硅胶置于质量分数２０％盐酸中ꎬ于２５ħ机械搅拌１０ｈꎬ待反应结束后ꎬ用超纯水多次洗涤至中性ꎬ于６５ħ鼓风烘箱干燥３ｈꎬ６５ħ真空烘箱干燥１０ｈꎬ得酸化硅胶ꎮ称取２０ｇ酸化硅胶ꎬ置于１５０ｍＬ三口圆底烧瓶中ꎬ加入１００ｍＬ除水甲苯ꎬ分别加入不同体积乙二胺￣Ｎ￣丙基三甲氧基硅烷(３.４㊁４.１㊁４.８㊁５.５㊁６.８㊁８.２ｍＬꎬＰＳＡ编号分别为１＃㊁２＃㊁３＃㊁４＃㊁５＃和６＃)ꎬ通Ｎ２作为保护气ꎬ机械搅拌下于５０ħ冷凝回流反应２４ｈꎬ待反应完成后ꎬ冷却过滤ꎬ依次采用５０ｍＬ甲苯㊁３次５０ｍＬ甲醇洗涤ꎬ于８０ħ鼓风烘箱预烘ꎬ８０ħ真空烘箱干燥过夜得不同键合量的ＰＳＡꎬ其反应式如图１所示ꎮ图１㊀乙二胺￣Ｎ￣丙基键合硅胶(ＰＳＡ)的键合反应式Ｆｉｇ.１㊀ＢｏｎｄｉｎｇｐｒｏｃｅｓｓｏｆＮ￣ｐｒｏｐｙｌｅｔｈｙｌｅｎｅｄｉａｍｉｎｅｓｉｌｉｃａｇｅｌ(ＰＳＡ)１.２.２㊀ＰＳＡ中试放大实验中试放大实验在１０Ｌ带机械搅拌控温反应釜中进行ꎬ加入２ｋｇ酸化硅胶㊁５５０ｍＬ乙二胺￣Ｎ￣丙基三甲氧基硅烷和７Ｌ除水甲苯ꎬ通Ｎ２作为保护气ꎬ机械搅拌下于５０ħ冷凝回流反应２４ｈꎬ待反应完成后ꎬ冷却过滤ꎬ依次采用甲苯和甲醇进行洗涤ꎬ于８０ħ鼓风烘箱预烘ꎬ８０ħ真空烘箱干燥过夜得中试键合ＰＳＡꎮ１.３㊀ＰＳＡ离子交换容量的测定ＰＳＡ上键合的乙二胺￣Ｎ￣丙基官能团上的两个胺基可以与Ｈ＋发生酸碱中和反应ꎬ因此通过电位滴定仪和ｐＨ电极可以测定ＰＳＡ的离子交换容量:称取０.２ｇＰＳＡ于锥形瓶中ꎬ加入１２０ｍＬ浓度为０.０１ｍｏｌ/Ｌ的ＨＣｌ水溶液ꎬ超声１０ｍｉｎꎬ静置１~２ｈꎬ使填料上的胺基和溶液中的Ｈ＋充分反应ꎬ用移液管移取上清液５０ｍＬ于锥形瓶中ꎬ确保没过ｐＨ电极ꎬ加入１~２滴酚酞指示剂ꎬ用０.０１ｍｏｌ/ＬＮａＯＨ标准溶液滴定剩余的ＨＣｌꎬ滴定终点时ꎬ记录消耗ＮａＯＨ水溶液的体积ꎬ同时做空白ꎬ通过式(１)计算ꎬ可以得到离子交换容量(ＩＥＣ)ꎬ平行３次取平均值ꎮＩＥＣ＝ｃ１Ｖ１－ｃ２Ｖ２/Ｖ３/Ｖ１()[]ｍꎬ(１)式中ꎬｃ１为ＨＣｌ溶液浓度ꎬｍｏｌ/ＬꎻＶ１为ＨＣｌ溶液体积ꎬｍＬꎻｃ２为ＮａＯＨ溶液浓度ꎬｍｏｌ/ＬꎻＶ２为ＮａＯＨ溶液体积ꎬｍＬꎻＶ３为移取上清液体积ꎬｍＬꎻｍ为ＰＳＡ质量ꎬｇꎮ１.４㊀ＰＳＡ脱除银杏酸１.４.１㊀银杏酸含量检测方法参考中国药典 银杏叶提取物 中银杏酸高效液相色谱检测(ＨＰＬＣ)方法ꎬ色谱柱为Ｃ１８柱(４.６ｍｍˑ１５０ｍｍꎬ５μｍ)ꎬ流动相(Ａ)为体积分数０.１％三氟乙酸的乙腈ꎬ流动相(Ｂ)为体积分数０.１％三氟乙酸的水ꎮ紫外检测波长为３１０ｎｍꎬ流速为１.０ｍＬ/ｍｉｎꎬ柱温为３５ħꎬ进样量为１０μＬꎮ流动相梯度:０~３０ｍｉｎꎬ流动相Ａ从７５％升到９０％ꎬ保持５ｍｉｎꎬ３５~３６ｍｉｎꎬ流动相Ａ从９０％降至７５％ꎬ保持９ｍｉｎꎮ以白果新酸为对照品ꎬ采用外标法进行定量ꎮ称取１０ｍｇ白果新酸标准品于１０ｍＬ容量瓶中ꎬ甲醇溶解定容ꎬ配制成质量浓度１０００μｇ/ｍＬ的母液ꎮ用甲醇将母液稀释成质量浓度分别为０.１㊁０.２５㊁０.５㊁１㊁５㊁１０㊁２５μｇ/ｍＬ的标准工作液ꎬ采用ＨＰＬＣ进行检测绘制标准曲线ꎮ１.４.２㊀银杏叶提取物的制备取３０ｇ银杏叶粉末于５００ｍＬ蓝盖瓶中ꎬ加入３００ｍＬ的乙醇ꎬ摇匀ꎬ超声１ｈꎬ抽滤并收集滤液ꎻ剩余滤渣再用３００ｍＬ的乙醇超声提取１ｈꎬ抽滤后合并滤液得到银杏叶提取液ꎮ取５０ｍＬ银杏液提取液进行旋转蒸发ꎬ将溶剂蒸干后得到０.３３ｇ银杏叶提取物ꎮ１.４.３㊀分离纯化柱的装填在低压分离纯化柱管底部放入筛板ꎬ将柱管连接至真空抽滤瓶ꎮ取５ｇＰＳＡ填料用乙醇－水(体积比４ʒ１)２５ｍＬ分散ꎬ超声１~２ｍｉｎ后用移液枪沿着管壁旋转加入到吸附柱中ꎬ抽干溶剂后将柱管顶部放入筛板压实ꎬ拧紧顶部盖子后完成装填ꎮ２㊀结果与讨论２.１㊀ＰＳＡ的制备ＰＳＡ硅胶上乙二胺￣Ｎ￣丙基的键合量与其离子交换容量成正比关系ꎬ因此本文通过检测离子交换容量来反映乙二胺￣Ｎ￣丙基键合量的变化趋势ꎮ图２㊀硅烷化试剂用量与离子交换容量关系图Ｆｉｇ.２㊀Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｖｏｌｕｍｅｏｆｓｉｌａｎｅｒｅａｇｅｎｔａｎｄｉｏｎｅｘｃｈａｎｇｅｃａｐａｃｉｔｙ２.１.１㊀ＰＳＡ制备工艺优化以２０ｇ酸化硅胶为原料ꎬ进行ＰＳＡ键合反应小试制备工艺优化ꎮ首先优化反应体系中乙二胺￣Ｎ￣丙基三甲氧基硅烷用量对离子交换容量的影响ꎮ构建６种键合反应体系ꎬ分别得到１＃~６＃键合ＰＳＡꎬ每种反应体系重复３次考察键合反应的批次重复性ꎬ１＃~６＃键合ＰＳＡ的离子交换容量相对标准偏差值范围为０.７％~５.９％ꎬ批次重复性良好ꎮ以ＰＳＡ离子交换容量平均值为纵坐标㊁乙二胺￣Ｎ￣丙基三甲氧基硅烷体积为横坐标作图(图２)ꎬ考察ＰＳＡ键合量与硅烷化试剂用量间的关系ꎮ结果表明:当体系中乙二胺￣Ｎ￣丙基三甲氧基硅烷少于５.５ｍＬ时ꎬ离子交换容量随硅烷化试剂用量增加而快速升高ꎬ而体系中乙二胺￣Ｎ￣丙基三甲氧基硅烷体积达到５.５ｍＬ之后ꎬ离子交换容量增加趋势变平缓ꎮ原因是当硅胶表面硅羟基趋于键合饱和时ꎬ由于反应活性位点减少导致继续增加硅烷化试剂的量其键合量增加不明显ꎮ同时ꎬ体系中过剩的未反应硅烷化试剂可发生自交联反应ꎬ造成硅胶孔结构的堵塞ꎬ硅胶表面积降低ꎮ因此ꎬ对于ＰＳＡ小试制备工艺体系ꎬ选择加入的乙二胺￣Ｎ￣丙基三甲氧基硅烷体积为５.５ｍＬꎮ２.１.２㊀ＰＳＡ的中试放大实验为了验证ＰＳＡ制备小试优化的工艺可以成功应用于中试放大实验ꎬ按照小试工艺优化的物料比ꎬ酸化硅胶和乙二胺￣Ｎ￣丙基三甲氧基硅烷的量分别放大１００倍ꎬ即２ｋｇ酸化硅胶和５５０ｍＬ乙二胺￣Ｎ￣丙基三甲氧基硅烷ꎬ溶剂除水甲苯的量放大７０倍ꎬ即７Ｌꎬ在１０Ｌ带机械搅拌机控温反应釜中进行中试放大实验ꎮ若完全按照小试优化工艺全部放大１００倍ꎬ体积超出１０Ｌ反应釜的承载范围ꎬ因此对溶剂除水甲苯的放大倍数较少为７０倍ꎬ经实验表明物料的分散和搅拌均满足实验要求ꎮ键合反应的键合温度㊁键合时间以及清洗步骤均参照小试工艺进行ꎮ键合反应重复３次ꎬ采用ＰＳＡ的离子交换容量重复性评价中试放大实验的批次稳定性ꎬ结果列于表１ꎬ结果表明:采用最佳工艺中试放大实验离子交换容量重复性良好ꎬ三批次重复性相对标准偏差仅为０.７％ꎮ中试放大实验的离子交换容量与小试相比略有提升ꎬ原因可能为中试放大实验中溶剂除水甲苯的用量相对减少３０％ꎬ因此单位溶剂中硅烷化试剂的浓度提升ꎬ从而导致键合量略有提升ꎮ与商品化ＰＳＡ相比ꎬ最佳工艺中试放大实验制备的ＰＳＡ可达到甚至优于商品化ＰＳＡ的离子交换容量ꎬ说明中试放大合成工艺的可行性ꎮ表１㊀最佳工艺中试放大三批次ＰＳＡ离子交换容量及其相对标准偏差Ｔａｂｌｅ１㊀Ｔｈｅｉｏｎｅｘｃｈａｎｇｅｃａｐａｃｉｔｙａｎｄｉｔｓｒｅｌａｔｉｖｅｓｔａｎｄａｒｄｄｅｖｉａｔｉｏｎｏｆ批次１２.３１０.７批次２２.２９批次３２.３４商品化１.９４２.２㊀ＰＳＡ的表征２.２.１㊀红外光谱对裸硅胶和ＰＳＡ进行傅里叶红外光谱(ＦＴＩＲ)表征ꎬ图３为两者的ＩＲ谱图ꎮ裸硅胶谱图中１１００ｃｍ－１处的吸收峰为硅胶上Ｓｉ Ｏ键的弯曲振动峰ꎬ３４６０ｃｍ－１和１６４０ｃｍ－１处的吸收峰分别为硅胶表面残留硅羟基Ｏ Ｈ键的伸缩振动和弯曲振动峰ꎮ与裸硅胶相比ꎬＰＳＡ谱图中在３４６０ｃｍ－１处出现了更为明显Ｎ Ｈ键的伸缩振动峰[２０]ꎬ在７０８ｃｍ－１处出现了 ＮＨ２的变形振动吸收峰ꎬ在２９６０ｃｍ－１和２８６０ｃｍ－１处出现了 ＣＨ的不对称和对称伸缩振动峰ꎬ表明乙二胺￣Ｎ￣丙基基团被成功键合到硅胶上ꎮ图３㊀裸硅胶和ＰＳＡ傅里叶红外光谱图Ｆｉｇ.３㊀ＩｎｆｒａｒｅｄｓｐｅｃｔｒｕｍｏｆｂａｒｅｓｉｌｉｃａｇｅｌａｎｄＰＳＡ２.２.２㊀元素分析将小试工艺优化构建的６种反应体系所得ＰＳＡ进行元素分析测试ꎮ如图４所示ꎬＰＳＡ的碳㊁氮和氢元素质量分数随着键合反应体系中乙二胺￣Ｎ￣丙基三甲氧基硅烷用量的增加而快速上升ꎬ当乙二胺￣Ｎ￣丙基三甲氧基硅烷用量达到小试最优工艺５.５ｍＬ时ꎬ所得ＰＳＡ的碳㊁氮和氢元素质量分数分别为６.３９％㊁２.８６％和２.０３％ꎬ然而硅烷化试剂用量继续增加时ꎬ碳㊁氮和氢元素质量分数增加趋势变平缓ꎮ结果表明:ＰＳＡ的碳㊁氮和氢元素质量分数与硅胶上键合的乙二胺￣Ｎ￣丙基的量成正比ꎬ其变化趋势与离子交换容量的变化趋势相符合ꎬ因此小试制备工艺中乙二胺￣Ｎ￣丙基三甲氧基硅烷用量为５.５ｍＬ时ꎬ键合量开始趋于饱和ꎮ图４㊀小试制备工艺优化中６种ＰＳＡ元素分析结果Ｆｉｇ.４㊀Ａｎａｌｙｓｉｓｒｅｓｕｌｔｓｏｆ６ｋｉｎｄｓＰＳＡｅｌｅｍｅｎｔｓｉｎｔｈｅｏｐｔｉｍｉｚａｔｉｏｎｏｆｔｈｅｓｍａｌｌ￣ｓｃａｌｅｐｒｅｐａｒａｔｉｏｎｐｒｏｃｅｓｓ㊀㊀表２为最佳工艺中试放大实验所得３批次ＰＳＡ的元素分析结果ꎬ与小试最佳工艺相比略有微ꎬ与离子交换容量的结果相符ꎮ与商品化ＰＳＡ的元素分析结果相比ꎬ碳㊁氮和氢元素含量可达到甚至优于商品化ＰＳＡꎮ表２㊀最佳工艺中试放大实验及商品化ＰＳＡ元素分析Ｔａｂｌｅ２㊀ＰＳＡ批次２２.７９６.３７１.７１批次３３.３１７.４６２.０３安捷伦２.７３６.４７１.７７２.３㊀ＰＳＡ对银杏酸的吸附研究将中试放大制备的ＰＳＡ填装成分离纯化小柱ꎬ用于银杏叶提取物中银杏酸的脱除ꎮ在真空作用下使银杏叶提取物通过小柱ꎬ收集净化液进行高效液相色谱分析ꎬ定量检测净化液中白果新酸含量ꎮ２.３.１㊀白果新酸标准曲线的建立将质量浓度分别为０.１０㊁０.２５㊁０.５０㊁１.００㊁５.００㊁１０.００㊁２５.００μｇ/ｍＬ的白果新酸标准工作液进行高效液相色谱分析ꎬ绘制标准工作曲线ꎮ所得标准工作曲线的线性回归方程为ｙ＝６６３６.１ｘꎬ相关系数ｒ２＝０.９９３３ꎮ图５为白果新酸标准品液相色谱图(质量浓度为２５μｇ/ｍＬ)ꎮ图５㊀白果新酸标准品高效液相色谱图Ｆｉｇ.５㊀Ｈｉｇｈｐｅｒｆｏｒｍａｎｃｅｌｉｑｕｉｄｃｈｒｏｍａｔｏｇｒａｐｈｙｏｆｇｉｎｋｇｏｎｅｗａｃｉｄｓｔａｎｄａｒｄ图６㊀银杏叶提取物上样体积与净化液中白果新酸浓度关系图Ｆｉｇ.６㊀Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｓａｍｐｌｅｌｏａｄｉｎｇｖｏｌｕｍｅｏｆｇｉｎｋｇｏｂｉｌｏｂａｅｘｔｒａｃｔａｎｄｃｏｎｃｅｎｔｒａｔｉｏｎｏｆｇｉｎｋｇｏｂｉｌｏｂａｎｅｗａｃｉｄｉｎｐｕｒｉｆｉｃａｔｉｏｎｓｏｌｕｔｉｏｎ２.３.２㊀ＰＳＡ离子交换容量对银杏酸脱除效率的影响ＰＳＡ键合的乙二胺￣Ｎ￣丙基官能团含有一个伯胺基团和一个仲胺基团ꎬ其与银杏酸含有的羧基以及酚羟基之间存在酸碱作用力ꎬ因此ＰＳＡ对银杏酸具有强吸附作用ꎮ当银杏叶提取物通过ＰＳＡ分离纯化柱时ꎬ银杏酸被吸附到填料上ꎬ从而达到银杏酸脱除的目的ꎮ为了考察ＰＳＡ离子交换容量对银杏酸脱除效率的影响ꎬ选取２＃㊁３＃㊁４＃㊁５＃ＰＳＡ进行脱酸实验ꎮ每支ＰＳＡ分离纯化柱总上样体积为２５ｍＬ银杏叶提取物ꎬ前１０ｍＬ上样体积间隔为２ｍＬꎬ之后上样体积间隔改为１ｍＬꎬ收集净化液定量分析白果新酸含量ꎮ银杏叶提取物的上样体积与净化液中白果新酸含量的关系图如图６所示:(１)２＃㊁３＃㊁４＃和５＃ＰＳＡ分离纯化柱对白果新酸的突破体积(脱除效率为１００％)ꎬ分别为１５㊁１６㊁１７㊁１８ｍＬꎬ结果表明随着离子交换容量的增加ꎬ突破体积增大ꎬ当上样体积大于１８ｍＬ时ꎬ所有ＰＳＡ柱的净化液中均检出白果新酸ꎮ(２)«中国药典»中规定银杏叶提取物中银杏酸质量分数不得超过５ｍｇ/ｋｇꎬ因此本文将净化液中白果新酸含量不高于５ｍｇ/ｋｇ的上样体积作为最大上样体积ꎬ２＃㊁３＃㊁４＃和５＃ＰＳＡ分离纯化柱的最大上样体积分别为２１㊁２２㊁２３和２４ｍＬꎮ因此ꎬＰＳＡ离子交换容量越高ꎬ对银杏酸的吸附效率越高ꎬＰＳＡ的离子交换容量与银杏酸脱除效率成正相关关系ꎮ图７为４＃键合ＰＳＡ分离净化柱上样体积分别为１７ｍＬ和２３ｍＬ所得净化液以及原始银杏叶提取物的ＨＰＬＣ色谱图ꎮ原始银杏叶提取物中白果新酸质量分数为６６８２ｍｇ/ｋｇꎬ４＃ＰＳＡ分离净化柱上样体积分别为１７ｍＬ和２３ｍＬ所得净化液中白果新酸质量分数分别为０和４.１ｍｇ/ｋｇꎮ图７㊀４＃键合ＰＳＡ分离净化柱上样体积分别为１７ｍＬ和２３ｍＬ所得净化液以及原始银杏叶提取物的ＨＰＬＣ色谱图Ｆｉｇ.７㊀ＨＰＬＣＣｈｒｏｍａｔｏｇｒａｍｏｆｐｕｒｉｆｉｅｄｓｏｌｕｔｉｏｎａｎｄｏｒｉｇｉｎａｌＧｉｎｋｇｏＢｉｌｏｂａｅｘｔｒａｃｔｗｉｔｈｓａｍｐｌｅｖｏｌｕｍｅｓｏｆ１７ｍＬａｎｄ２３ｍＬｏｎ４＃ｂｏｎｄｅｄＰＳＡｓｅｐａｒａｔｉｏｎａｎｄｐｕｒｉｆｉｃａｔｉｏｎｃｏｌｕｍｎ３㊀结论本文通过考察ＰＳＡ小试制备工艺中硅烷化试剂与离子交换容量的变化关系ꎬ制备一系列离子交换容量不同的ＰＳＡ并得到最优小试制备工艺ꎮ将最优小试制备工艺在１０Ｌ反应釜中进行公斤级中试放大实验ꎬ验证最优小试制备工艺的放大效果ꎬ对工业批量生产ＰＳＡ具有一定借鉴意义ꎮ对中试实验制备㊁小试制备及商品化ＰＳＡ进行离子交换容量㊁红外光谱和元素分析表征ꎬ并将其结果进行比较ꎬ结果表明中试放大实验得到的ＰＳＡ性能与最优小试工艺相符ꎬ中试放大实验成功ꎬ并且其性能与商品化ＰＳＡ性能相当ꎮ本文优化的制备工艺对工业生产ＰＳＡ硅胶填料具有借鉴价值ꎮ将ＰＳＡ装填成分离纯化小柱应用于银杏叶提取物中银杏酸的脱除ꎬ发现白果新酸的脱除效率与ＰＳＡ的离子交换容量成正相关关系ꎮ４＃键合ＰＳＡ分离纯化柱对白果新酸脱除的突破体积和最大上样体积分别达到１７ｍＬ和２３ｍＬꎬ结果表明键合ＰＳＡ在银杏酸脱除方面具有应用潜力ꎮ参考文献:[１]宋祥家ꎬ李红霞.胺类硅胶材料的合成及应用[Ｊ].化工技术与开发ꎬ２０１２ꎬ４１(８):２６￣２８.ＤＯＩ:１０.３９６９/ｊ.ｉｓｓｎ.１６７１￣９９０５.２０１２.０８.００８.[２]王明华.硅胶负载酰胺 胺型螯合树脂的合成及性能研究[Ｄ].烟台:鲁东大学ꎬ２００８.[３]朱萌.胺类聚合物型亲水作用色谱固定相的制备及色谱性能评价[Ｄ].青岛:青岛科技大学ꎬ２０１９.[４]王玲慧.乙二胺硅胶材料的制备及其吸附性能研究[Ｄ].郑州:郑州大学ꎬ２０１０.[５]包建民ꎬ王惠柳ꎬ李优鑫.ＨＰＬＣ级二氧化硅微球的制备及其功能化[Ｊ].精细化工ꎬ２０１８ꎬ３５(９):１４５７￣１４６５.ＤＯＩ:１０.１３５５０/ｊ.ｊｘｈｇ.２０１７０５１４.[６]李来明ꎬ任芳芳ꎬ包建民ꎬ等.７种胺基键合硅胶的制备及其对重金属Ｐｂ２＋的吸附[Ｊ].色谱ꎬ２０２０ꎬ３８(３):３４１￣３４９.ＤＯＩ:１０.３７２４/ＳＰ.Ｊ.１１２３.２０１９.０９０３０.[７]ＡＧＵＡＤＯＪꎬＡＲＳＵＡＧＡＪＭꎬＡＲＥＮＣＩＢＩＡＡ.ＩｎｆｌｕｅｎｃｅｏｆｓｙｎｔｈｅｓｉｓｃｏｎｄｉｔｉｏｎｓｏｎｍｅｒｃｕｒｙａｄｓｏｒｐｔｉｏｎｃａｐａｃｉｔｙｏｆｐｒｏｐｙｌｔｈｉｏｌｆｕｎｃｔｉｏｎａｌｉｚｅｄＳＢＡ￣１５ｏｂｔａｉｎｅｄｂｙｃｏ￣ｃｏｎｄｅｎｓａｔｉｏｎ[Ｊ].ＭｉｃｒｏｐｏｒｏｕｓａｎｄＭｅｓｏｐｏｒｏｕｓＭａｔｅｒｉａｌｓꎬ２００８ꎬ１０９(１/２/３):５１３￣５２４.ＤＯＩ:１０.１０１６/ｊ.ｍｉｃｒｏｍｅｓｏ.２００７.０５.０６１.[８]王军ꎬ扎西次旦ꎬ黄利英ꎬ等.基于Ｎ￣丙基乙二胺键合硅胶和十八烷基键合锆胶的ＱｕＥＣｈＥＲＳ￣气相色谱－质谱法检测酥油中的８种有机磷农药残留[Ｊ].食品安全质量检测学报ꎬ２０１９ꎬ１０(２１):７３６０￣７３６４.ＤＯＩ:１０.１９８１２/ｊ.ｃｎｋｉ.ｊｆｓｑ１１￣５９５６/ｔｓ.２０１９.２１.０５０.[９]蒋明明ꎬ曾小娟ꎬ宋红坤ꎬ等.多壁碳纳米管/Ｎ－丙基乙二胺混合吸附－超高效液相色谱－串联质谱法测定普洱茶中３种手性杀菌剂农药残留[Ｊ].食品安全质量检测学报ꎬ２０２０ꎬ１１(６):１７０２￣１７０８.ＤＯＩ:１０.１９８１２/ｊ.ｃｎｋｉ.ｊｆｓｑ１１￣５９５６/ｔｓ.２０２０.０６.００２. 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[１１]池静端.银杏叶中黄酮类成分的化学研究[Ｊ].中国中药杂志ꎬ１９９８ꎬ２３(１):４０￣４１.[１２]杨小明ꎬ陈钧ꎬ钱之玉.烷基酚酸的生物活性研究进展[Ｊ].中草药ꎬ２００３ꎬ３４(５):Ｕ００５￣Ｕ００６.ＤＯＩ:１０.３３２１/ｊ.ｉｓｓｎ:０２５３￣２６７０.２００３.０５.０４７.[１３]沈琦ꎬ李贺ꎬ廉洪ꎬ等.银杏酸对大鼠肝毒性的影响研究[Ｊ].中国临床药理学杂志ꎬ２０１８ꎬ３４(１２):１４５７￣１４５９.ＤＯＩ:１０.１３６９９/ｊ.ｃｎｋｉ.１００１￣６８２１.２０１８.１２.０１８.[１４]ＩＲＩＥＪꎬＭＵＲＡＴＡＭꎬＨＯＭＭＡＳ.Ｇｌｙｃｅｒｏｌ￣３￣ｐｈｏｓｐｈａｔｅｄｅｈｙｄｒｏｇｅｎａｓｅｉｎｈｉｂｉｔｏｒｓꎬａｎａｃａｒｄｉｃａｃｉｄｓꎬｆｒｏｍＧｉｎｋｇｏｂｉｌｏｂａ[Ｊ].ＢｉｏｓｃｉｅｎｃｅꎬＢｉｏｔｅｃｈｎｏｌｏｇｙꎬａｎｄＢｉｏｃｈｅｍｉｓｔｒｙꎬ１９９６ꎬ６０(２):２４０￣２４３.ＤＯＩ:１０.１２７１/ｂｂｂ.６０.２４０.[１５]张秀丽ꎬ杨小明ꎬ夏圣ꎬ等.银杏酸对痤疮致病菌的抑制作用[Ｊ].江苏大学学报(医学版)ꎬ２００７ꎬ１７(６):５２３￣５２５.ＤＯＩ:１０.１３３１２/ｊ.ｉｓｓｎ.１６７１￣７７８３.２００７.０６.００４.[１６]王云飞ꎬ杨小明ꎬ李月英ꎬ等.银杏酚对ＳＭＭＣ￣７７２１肝癌细胞和荷Ｈ２２肝癌小鼠的抗癌作用[Ｊ].江苏大学学报(医学版)ꎬ２０１３ꎬ２３(３):２３３￣２３７.ＤＯＩ:１０.１３３１２/ｊ.ｉｓｓｎ.１６７１￣７７８３.２０１３.０３.０１８.[１７]姚建标ꎬ金辉辉ꎬ王如伟ꎬ等.银杏叶提取物中总银杏酸ＨＰＬＣ法限量检测[Ｊ].药物分析杂志ꎬ２０１５ꎬ３５(１１):２０４１￣２０４４.ＤＯＩ:１０.１６１５５/ｊ.０２５４￣１７９３.２０１５.１１.３０.[１８]国家药典委员会.中华人民共和国药典２０２０年版一部[Ｓ].北京:中国医药科技出版社ꎬ２０２０.[１９]辛云海.银杏叶化学成分及银杏酚酸脱除工艺的研究[Ｄ].桂林:广西师范大学ꎬ２００７.[２０]ＹＵＪＧꎬＬＥＹꎬＣＨＥＮＧＢ.ＦａｂｒｉｃａｔｉｏｎａｎｄＣＯ２ａｄｓｏｒｐｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｂｉｍｏｄａｌｐｏｒｏｕｓｓｉｌｉｃａｈｏｌｌｏｗｓｐｈｅｒｅｓｗｉｔｈａｍｉｎｅ￣ｍｏｄｉｆｉｅｄｓｕｒｆａｃｅｓ[Ｊ].ＲＳＣＡｄｖａｎｃｅｓꎬ２０１２ꎬ２(１７):６７８４￣６７９１.ＤＯＩ:１０.１０３９/Ｃ２ＲＡ２１０１７Ｇ.。

Functionalized micelles from block copolymer of polyphosphoester and poly(ɛ-caprolactone)for receptor-mediated drug deliveryYu-Cai Wang a,1,Xi-Qiu Liu b,1,Tian-Meng Sun b ,Meng-Hua Xiong a ,Jun Wang a,b,⁎aDepartment of Polymer Science and Engineering,University of Science and Technology of China,Hefei,Anhui 230026,PR ChinabHefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences,University of Science and Technology of China,Hefei,Anhui 230027,PR ChinaReceived 23October 2007;accepted 29January 2008Available online 16February 2008AbstractCellular specific micellar systems from functional amphiphilic block copolymers are attractive for targeted intracellular drug delivery.In this study,we developed reactive micelles based on diblock copolymer of poly(ethyl ethylene phosphate)and poly(ɛ-caprolactone).The micelles were further surface conjugated with galactosamine to target asialoglycoprotein receptor (ASGP-R)of HepG2cells.The size of micellar nanoparticles was about 70nm in diameter,and nanoparticles were negatively charged in aqueous solution.Through recognition between galactose ligands with ASGP-R of HepG2cells,cell surface binding and internalization of galactosamine-conjugated micelles were significantly promoted,which were demonstrated by flow cytometric analyses using rhodamine 123fluorescent dye.Paclitaxel-loaded micelles with galactose ligands exhibited comparable activity to free paclitaxel in inhibiting HepG2cell proliferation,in contrast to the poor inhibition activity of micelles without galactose ligands particularly at lower paclitaxel doses.In addition,population of HepG2cells arrested in G2/M phase was in positive response to paclitaxel dose when cells were incubated with paclitaxel-loaded micelles with galactosamine conjugation,which was against the performance of micelles without galactose ligand,owing to the ligand –receptor interaction.The surface functionalized micellar system is promising for specific anticancer drug transportation and intracellular drug release.©2008Elsevier B.V .All rights reserved.Keywords:Polyphosphoester;Biodegradable block copolymer;Receptor-mediated drug delivery;Reactive micelle;HepG2cells1.IntroductionDrug delivery systems using soluble polymers,liposomes,and self-assembled nanoparticles etc.have been developed to reduce the side effects and increase the therapeutic efficacy of anticancer drugs [1–4].Among them,loading drug molecules into the hydrophobic core of self-assembled polymer micelles in a mesoscopic size range (several tens of nanometers)is one of the resolutions to increase solubility of hydrophobic drug.Such micellar nanoparticles passively accumulate in solid tumortissues via enhanced permeability and retention (EPR)effect and enhance therapeutic efficacy [4,5].Polymeric micellar na-noparticles can be thermodynamically stable,and the hydrophil-ic shell ensures its stable dispersion in aqueous solution through a steric stabilization effect,which facilitates its long term blood circulation following intravenous injection [6].These advan-tages make polymer micellar nanoparticles promising for hy-drophobic drug delivery.Challenge is remained in development of cellular specific polymeric micellar system for targeted drug delivery.Biofunc-tional molecules or ligands are expected to be conjugated to micelle surface for specific cell binding and internalization.In this regard,functionable groups at the end of hydrophilic polymer segments are generally required for bioconjugation.Most reported functionalized polymeric micellar systems are based on block copolymers of hydrophobic aliphatic polyester andAvailable online at Journal of Controlled Release 128(2008)32–40/locate/jconrelCorresponding author.Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences,University of Science and Technology of China,Hefei,Anhui 230027,PR China.Tel.:+865513600335;fax:+865513600402.E-mail address:jwang699@ (J.Wang).1Contribute equally to this work.0168-3659/$-see front matter ©2008Elsevier B.V .All rights reserved.doi:10.1016/j.jconrel.2008.01.021functionalized hydrophilic poly(ethylene glycol).For example, Kataoka et al.reported sugar and small peptidyl ligands modified polymer micelles and reactive polymer micelles based on an aldehyde-ended poly(ethylene glycol)/poly(lactide)block copo-lymer[7,8].Langer et ed carboxy-terminated poly(D,L-lactide-co-glycolide)-block–poly(ethylene glycol)to fabricate micellar nanoparticles for surface conjugation of prostate specific membrane antigen binding aptamer[9–11].Liang et al.reported polymer micelles of poly(γ-benzyl L-glutamate)/poly(ethylene glycol)diblock copolymer end capped with galactose moiety for liver targeted drug delivery[12].Instead of conjugation to the end of hydrophilic polymer segments,biofunctional molecules or ligands have also been conjugated to the side groups of hydrophilic block,such as galactosamine-conjugated micelles based on poly(γ-glutamic acid)(γ-PGA)and poly(lactide)(PLA) block copolymer[13–15].In the past few years,we have developed biocompatible po-lyphosphoesters for drug/gene delivery and tissue engineering, taking their advantages of biodegradability and structural flex-ibility[16–18].We have reported two convenient methods to synthesize structurally and compositionally defined block copolymer of poly(ɛ-caprolactone)(PCL)and polyphosphoester. One method was sequential polymerization ofɛ-caprolactone and cyclic phosphoester monomer with trimer of aluminum isoprop-oxide as the initiator[19].The other method was to use PCL macroinitiator to initiate cyclic phosphoester monomer polymer-ization with stannous octoate as the catalyst[20].Through these two methods,polyphosphoesters with hydroxyl end groups can be conveniently synthesized.On the other hand,we have recently demonstrated in aqueous solution triblock copolymers of PCL and poly(ethyl ethylene phosphate)(PEEP)formed micellar nanoparticles with hydrophobic PCL core and hydrophilic PEEP shell[17].As compared with the well-known poly(ethylene glycol),hydrophilic polyphosphoesters may hold interesting properties for drug delivery system design since polypho-sphoesters are degradable and more structurally flexible for physicochemical property adjustment.The aim of this study is to develop reactive micelles for surface ligands conjugation using block copolymer of PCL and polyphosphoesters and study its potential for cellular specific drug delivery.We synthesized diblock copolymer of PCL and PEEP and further activated the hydroxyl end groups of PEEP by reaction with N,N′-carbonyldii-midazole.In aqueous solution,the activated diblock copolymer assembled into micellar nanoparticles with surface ready to react with amine(s).D-Galactosamine was then conjugated to the surface of these micellar nanoparticles.The potential of such system for targeted anticancer drug delivery to HepG2cells was studied by examining asialoglycoprotein receptor(ASGP-R) mediated cell binding and internalization ability and bioactivity of paclitaxel-loaded micelles.2.Materials and methods2.1.Materials2-Ethoxy-2-oxo-1,3,2-dioxaphospholane(EEP)was synthe-sized and purified as previously reported[20].Tetrahydrofuran (THF)was refluxed over potassium–sodium alloy under N2at-mosphere and distilled out just before use.PCL macroinitiatorbearing one hydroxyl end group per polymer chain(PCL67–OH) was synthesized by ring-opening polymerization ofɛ-caprolac-tone in THF using aluminum isopropoxide as the initiator[19].The polymerization degree of the PCL macroinitiator was67,which was calculated based on the integration ratio of the tripletresonance at4.03ppm(2H)and the singlet resonance at3.66ppm(2H)from its1H NMR.The molecular-weight distribution ofPCL67–OH was1.16which was determined by gel permeation chromatography(GPC)as described below.Stannous octoate(Sn (Oct)2)was purified according to a method described in literature [20].D-Galactosamine hydrochloride(98%),D-glucosamine hydrochloride(99%),N,N′-carbonyldiimidazole(CDI,98%), and paclitaxel were obtained from Sigma-Aldrich Co.All other solvents were of reagent grade and used as received.Dialysis membrane tubing Spectra/Por®Float-A-Lyzer(MWCO25,000) was obtained from Spectrum Laboratories,Inc.2.2.Syntheses and characterization of polymers2.2.1.Synthesis of block copolymer(PCL–PEEP)Block copolymer PCL–PEEP was obtained by ring-opening polymerization of EEP using PCL67–OH as the initiator and Sn (Oct)2as the catalyst.Briefly,to a solution of EEP(7.60g, 50.0mmol)and PCL67–OH(7.64g,1.0mmol)in THF at35°C was added Sn(Oct)2(0.41g,1.0mmol).After3h reaction,the mixture was concentrated and the polymer was precipitated in cold ethyl ether twice.The obtained block copolymer PCL–PEEP was dried under vacuum to a constant weight at room temperature.The yield was approximately75%.The degree of polymerization(DP)of EEP was calculated based on the integration ratio of resonance at 4.18and4.26ppm(6H),assigned to methylene protons of PEEP block,to resonance at2.35ppm(2H),assigned to the methylene protons of PCL block(Fig.1A).Based on this calculation,the DP of EEP was36,with respect to72%EEP conversion.The mol-ecular-weight distribution was1.40,determined by gel perme-ation chromatography.This copolymer was further denoted as PCL67–PEEP36.Fig.1.1H NMR spectra of PCL67–PEEP36(A),PCL67–PEEP36–CDI(B)and glucose-conjugated block copolymer(C).33Y.-C.Wang et al./Journal of Controlled Release128(2008)32–402.2.2.Synthesis of CDI activated block copolymer(PCL67––PEEP36––CDI)Block copolymer PCL67–PEEP36(1.0g)and CDI(65mg,5.0 equiv mol of hydroxyl groups)were dissolved in10mL of anhydrous THF.The solution was stirred at room temperature for 12h,and then concentrated.The polymer was precipitated into anhydrous ethyl ether.The activated block copolymer PCL67–PEEP36–CDI was obtained by filtration and then dried under vacuum.The yield was approximately90%.2.2.3.Characterization and measurementsBruker A V300NMR spectrometer(300MHz)was used for1H NMR spectrum analyses to determine the structure and composi-tion of block copolymers.Deuterated chloroform containing 0.03v/v%tetramethylsilane was used as the solvent for NMR measurements.Molecular weights and molecular-weight distri-butions were determined by gel permeation chromatography measurements on a Waters system,equipped with a Waters1515 HPLC solvent pump,a Waters2414refractive index detector,and four Waters Styragel columns(HR4,HR2,HR1,HR0.5,effective molecular-weight range5000–500,000,500–20,000,100–5000, 0–1000respectively).HPLC grade chloroform was purchased from J.T.Baker and used as the eluent at40°C,delivered at a flow rate of1.0mL min−1.Monodispersed polystyrene standards obtained from Waters Co.with a molecular-weight range1310–5.51×104were used to generate the calibration curve.2.3.Preparation and characterization of polymer micelles2.3.1.Preparation of micellesMicelles were prepared by a dialysis method.PCL67–PEEP36–CDI(50mg)was dissolved in5mL of THF.To this solution was added dropwise100mL of Milli-Q water(Millipore Milli-Q Synthesis,18.2MΩ)under gentle stirring.After standing at room temperature for3h,THF was removed by dialysis against Milli-Q water for24h.2.3.2.Conjugation of D-galactosamine and D-glucosamine to micelle surfaceD-Galactosamine or D-glucosamine was conjugated to micelle surface via reaction with micelles as described above.D-Galac-tosamine or D-glucosamine was dissolved into micelles at pH9.0. After24h reaction at room temperature,micelles were dialyzed against Milli-Q water for24h to remove free D-galactosamine or D-glucosamine.The contents of D-galactosamine and D-glucosa-mine conjugated to micelles were determined by the colorimetric Morgan Elson assay[21].2.3.3.Characterization of polymer micellesTo confirm the surface functionality of micelles,micelles in aqueous solution was lyophilized and dissolved in CDCl3.1H NMR spectrum was recorded using Bruker A V300NMR spectrometer(300MHz).The methods for critical micelle con-centration(CMC)determination,transmission electron micro-scopy(TEM)observation,and particle size and zeta potential measurements were described in detail in the supplementary information.2.4.Cell binding and internalization studies2.4.1.Preparation of rhodamine123-loaded micellesRhodamine123-loaded micelles were prepared in a similar method as described in Section 2.3.1.PCL67–PEEP36–CDI (10mg)and rhodamine123(0.1mg)were dissolved in THF (5mL),and10mL of Milli-Q water was added dropwise to this solution under gentle stirring.THF was removed by dialysis against water for24h.Conjugation of D-galactosamine or D-glu-cosamine to micelle surface was done as described in Section 2.3.2.Micelle with D-glucosamine or D-galactosamine conjuga-tion was denoted as NP-Glu or NP-Gal,respectively.The control micelles(NP)without any saccharide moiety was made using PCL67–PEEP36in a similar method.2.4.2.Binding of micelles to HepG2cellsHepG2cells(150,000cells per well)in24-well plates were precultured with100μL of rhodamine123-loaded NP,NP-Glu or NP-Gal in phosphate-buffered saline(PBS,1mg mL−1)at4°C for 1h.Cells were washed with ice-cold PBS and further cultured with1mL of complete DMEM(Dulbecco's Modified Eagle's Medium,containing10%Hyclone fetal bovine serum,50units mL−1penicillin and50units mL−1streptomycin)at37°C and5% CO2atmosphere.At different culture intervals,cells were se-parately harvested by trypsinization,washed with PBS and resus-pended in200μL of PBS for flow cytometric analysis using a Becton Dickinson FACSCalibur flow cytometer.2.4.3.Cellular uptake of micelles by HepG2cellsRhodamine123-loaded micelles(100μL,1mg mL−1in PBS)were incubated with150,000HepG2cells in1mL of complete DMEM culture medium.For the competing inhibition study,D-galactosamine was added to reach the final concentra-tion of20mM.After incubation at37°C for4h,cells were trypsinized,washed with PBS twice,resuspended in200μL of PBS and subjected to flow cytometric analysis.For microscopic observation,HepG2cells(5×104)were seeded on coverslip in a24-well tissue culture plate until they were totally adherent.100μL of Rhodamine123-loaded NP or NP-Gal(1mg mL−1in PBS)were added to distinct wells and incubated at37°C for2h in1mL of complete DMEM culture medium.The cells were washed and fixed with4%formalde-hyde and the slides were mounted and observed with a Zeiss LSM510Laser Confocal Scanning Microscope imaging system with an upright confocal microscope and a40×objective.2.5.Drug loading and activity analyses2.5.1.Preparation of paclitaxel-loaded micellesPaclitaxel was loaded into micelles by the dialysis method.In a typical procedure,the block copolymer(10mg)was dissolved in 1.0mL of THF,and to this solution was subsequently added paclitaxel dissolved in DMSO at various weight ratios to block copolymer(paclitaxel/polymer=0.05–0.1).Milli-Q water was then added dropwise to this solution.The mixture was stirred at room temperature for3h and filtered through0.45μm Millipore membrane filter.The solution was dialyzed for24h and freeze-34Y.-C.Wang et al./Journal of Controlled Release128(2008)32–40dried.Paclitaxel-loaded NP-Gal is further denoted as NP-Gal-PTX,while the control NP-PTX was made using PCL67–PEEP36 without D-galactosamine conjugation in a similar method.After dissolving paclitaxel-loaded micelles with acetonitrile–water(50:50,v/v),the loading amount of paclitaxel was deter-mined by HPLC analysis.HPLC analysis was performed on a Waters HPLC system consisting of Waters1525binary pump, Waters24872-channel UV–vis detector,1500column heater and a Symmetry C18column.HPLC grade acetonitrile–water (50:50,v/v)was used as the mobile phase at30°C with a flow rate of1.0mL min−1.UV–vis Detector was set at227nm and linked to Breeze software for data analysis.Linear calibration curves for concentrations in the range of0.098–100μg/mL were constructed using the peak areas by linear regression analysis.The regres-sion equation was calculated as y=42204x+8287.8(R2= 0.9996).The concentrations of paclitaxel were determined by comparing the peak area with the stand curve.The drug loading content(DLC)and drug loading efficiency(DLE)were calculated by the following equations:DLC¼weight of PTX in micellesweight of PTX loaded micellesÂ100kDLE¼weight of PTX in micellesweight of PTX used for encapsulationÂ100k2.5.2.In vitro paclitaxel release from micellesIn vitro release profiles of paclitaxel from micelles were investigated in phosphate-buffered saline(PBS,0.02mol L−1,pH 7.4)using a dialysis-bag diffusion technique.Micelles(1.5mL) were introduced into a dialysis membrane tubing and incubated in 25mL of buffer at37°C with stirring.At predetermined intervals, buffer were drawn and replaced with an equal volume of fresh medium.The concentration of paclitaxel in the solution was measured by HPLC.2.5.3.Viability of HepG2cells treated with paclitaxel-loaded micellesThe cytotoxicity of NP-Gal-PTX or NP-PTX against HepG2 cells was evaluated in vitro by MTT assay,using paclitaxel dissolved in DMSO as the control(the final concentration of DMSO in medium was1%v/v).HepG2cells were seeded in96-well plates at10,000cells per well in100μL of complete DMEM medium and incubated at37°C in5%CO2atmosphere for24h. The culture medium was replaced with100μL of fresh medium containing paclitaxel-loaded micelles.Various PTX concentra-tions were achieved by adding dilution of the micelle formulation with4.0%of drug loading content.Cells were further incubated for72h,followed by addition of25μL of MTT stock solution(5mg mL−1in PBS)to achieve a final con-centration of1mg mL−1.After incubation for an additional2h, 100μL of the extraction buffer(20%SDS in50%DMF,pH4.7, prepared at37°C)was added to the wells and incubated over-night at37°C.The absorbance of the solution was measured at 570nm using a Bio-Rad680microplate reader and cell viability was normalized to that of HepG2cells cultured in the culture medium without paclitaxel.2.5.4.Cell cycle analyses of HepG2cells treated with paclitaxel-loaded micellesHepG2cells cultured in24-well plates were treated for24hwith paclitaxel in DMSO,NP-PTX or NP-Gal-PTX at threedifferent paclitaxel doses(0.075,0.3,and1.2μM).For cellstreated with paclitaxel in DMSO,the final concentration ofDMSO in medium was kept at1%(v/v).The cells were tryp-sinized,washed with PBS,fixed with70%ethanol and cen-trifuged.The cell pellet was suspended with PBS and treatedwith200μL of propidium iodide(PI)staining solution(0.1%Triton X-100,0.2mg mL−1DNase-free RNase A and20μgmL−1PI)for15min at37°C.The fluorescence was measuredusing flow cytometer and cell cycle was analyzed usingWinMDI2.9software.3.Results and discussion3.1.Synthesis and characterization of block copolymersWe have previously reported polyphosphoesters with linearmolecular structure can be synthesized through ring-openingpolymerization of EEP in THF under co-initiation of dodecanoland Sn(Oct)2[20].Instead of dodecanol,we have also used PCLdiol as the initiator to synthesize triblock copolymer of PCL andPEEP[17].In this study,mono hydroxyl-terminated poly(ɛ-caprolactone)PCL67–OH was used as macroinitiator for EEP polymerization to obtain a diblock copolymer(Scheme1).Thefeeding molar ratio of PCL67–OH to EEP was1:50,while the reaction time was limited to3h since extension of reaction time will likely lead to chain exchange side reaction though EEP conversion can be increased[20].Such copolymer chains contain functional hydroxyl groupsat the end of PEEP segments,which was demonstrated by thepresence of resonance appeared at3.82ppm,assigned to me-thylene protons conjoint to hydroxyl end groups of polypho-sphoester block(Fig.1A)as reported by us previously[17,19].These hydroxyl end groups can be conveniently modified forbiofunctional molecules conjugation.As depicted in Scheme1,in this study,coupling reagent CDI was used to activatetheScheme1.Schematic illustration of syntheses of block copolymer and surface functionalized micelles.35Y.-C.Wang et al./Journal of Controlled Release128(2008)32–40hydroxyl groups and generate the carbonylimidazole derivative PCL67–PEEP36–CDI,while imidazole groups are known to be easily substituted under the attack of nucleophiles such as amines.1H NMR analysis of PCL67–PEEP36–CDI demon-strated the successful conversion of hydroxyl groups to car-bonylimidazole moieties.As shown in Fig.1B,no signal at 3.82ppm was further found in1H NMR spectrum of PCL67–PEEP36–CDI.Instead,newly appeared resonance at4.62ppm should be assigned to protons of methylene groups conjoined to the end carbonyl group of PCL67–PEEP36–CDI.In addition,the presence of resonances at7.21,7.45and8.20ppm,should be assigned to protons of imidazole residues,demonstrating the successful activation of hydroxyl groups of PEEP blocks.3.2.Micelle preparation and characterizationPCL67–PEEP36–CDI is amphiphilic and in aqueous medium it self-assembled to form micellar structure.The spherical morphology of micelles was demonstrated by TEM examina-tion,shown in the supplementary information(Fig.S1).The CMC value of PCL67–PEEP36–CDI,which describes the physical properties of the micelles relating to its thermodynamic stability,was determined by the method based on partition of pyrene probe in hydrophobic core against aqueous environment [22].The intensity ratio of the bands at339.0and335.5nm (I339.0/I335.5)as a function of the logarithm of the copolymer concentration was given in supplementary information(Fig.S2). The CMC value of PCL67–PEEP36–CDI,which was8.9×10−4mg mL−1,was taken at the intersection of the tangents to the horizontal line of intensity ratio with relatively constant values and the diagonal line with rapid increased intensity ratio.3.3.Conjugation of D-galactosamine and D-glucosamine to micelle surfaceD-Galactosamine and D-glucosamine were conjugated to mi-celle surface via substitution of imidazole by amino groups.To demonstrate the successful conjugation,micelle in aqueous solution was lyophilized after conjugation and the polymer was extracted into CDCl3for1H NMR analyses.As shown in Fig.1C, resonances corresponding to imidazole residue protons disap-peared.Instead,newly appeared peaks at3.3–3.8,5.01and 6.02ppm were due to the presence of glucosyl protons and its anomeric protons(a and a'),indicating the complete substitution of imidazole by glucosyl residues.The contents of D-galactosa-mine and D-glucosamine conjugated to micelles determined by the colorimetric Morgan Elson assay[21]were59.6±8.2nmol mg−1and65.1±10.2nmol mg−1,corresponding to78.2±10.7mol%and85.4±13.3mol%of total end groups,respectively. The CMC of sugar-conjugated block copolymer was comparable to PCL67–PEEP36and PCL67–PEEP36–CDI as determined by the same method described above.In addition,average size(about 70nm in diameter)and size distribution of micelles were not significantly affected after sugar conjugation that was measured by dynamic light scattering and given in supplemental informa-tion(Fig.S3A).However,with the conjugation of sugar mo-lecules,the micelles were more negatively charged compared with PCL67–PEEP36–CDI micelles.The average zeta potential value was around−20mV(Fig.S3B),which may promote micelle stabilization due to static repellency between particles.3.4.Cell binding and internalizationThe asialoglycoprotein receptor(ASGP-R)on the surface of hepatoma cells is a recycling endocytotic receptor and re-cognizes galactose-and N-acetylgalactosamine-terminaled gly-coproteins[23].To demonstrate the enhanced binding ability of galactosamine-conjugated micelles(NP-Gal)to HepG2cells, the micelles were loaded with rhodamine123fluorescent dye and incubated with HepG2cells at4°C.Micelles not bound to cell surfaces were washed off after1h incubation,and the cells were further cultured under normal cell culture conditions at 37°C.Because cell internalization of nanoparticles via endocy-tosis is an ATP-dependent process,micelles attached to cell surface should not be internalized by cells at4°C[24].Further incubation of cells with attached nanoparticles on cell membrane at37°C allowed micelle internalization into cells and rhodamine 123release.As shown in Fig.2A,the fluorescent intensity of HepG2cells right after1h treatment with NP-Gal micelles at4°C was slightly higher than those treated with non-modified micelles(NP)or glucosamine-conjugated micelles(NP-Glu), which was also indicated as the relative geometrical mean fluorescence intensity(GMFI)shown as the inset.The fluo-rescent positive cell population was around18%after incubation at4°C with NP-Gal.It is worth noting that high concentration of rhodamine123in micellar core might result influorescenceFig.2.Flow cytometric analyses of binding ability of non-modified micelles (NP,blue),glucosamine-conjugated micelles(NP-Glu,green),and galactosa-mine-conjugated micelles(NP-Gla,red)to HepG2cells.Cells were mixed with micelles at4°C for1h and further incubated at37°C for0(A),75(B),150(C) and180min(D).Blank cells incubated with micelle free medium were used as the control(purple).The relative geometrical mean fluorescence intensity (GMFI)of cells incubated with NP,NP-Glu and NP-Gal are shown as insets. (For interpretation of the references to colour in this figure legend,the reader is referred to the web version of this article.)36Y.-C.Wang et al./Journal of Controlled Release128(2008)32–40quenching therefore fluorescence detected by flow cytometry could be relatively weak.Fig.2B –D shows the results analyzed by flow cytometry when HepG2cells were further incubated at 37°C following the micelle attachments to cell membrane.It is obvious that with elongation of incubation time from 75to 180min,positive cell population (with log mean fluorescence intensity more than 101)increased from 28.9%to 76.6%,while the relative GMFI increased from 1.65to 6.39in the group treated with NP-Gal,indicating more rhodamine 123-loaded micelles attached to HepG2cells at 4°C were internalized and the cargo was released.In contrast,fluorescence of cells treated with NP or NP-Glu was much less pronounced due to their poor attachment to HepG2cells at 4°C.This phenomenon demon-strated that the ligand –receptor recognition between galactosyl residue and ASGP-R mediated the surface binding of micelles to HepG2cells.It is possible that negatively charged surface of micelles resulted in electrostatic repulsion to cells,which in fact is unfavorable to micelle binding to cell surface.Therefore,without receptor mediation,NP-Glu and NP had less chance to reach HepG2cell surface and be internalized into cells.In another experiment,HepG2cells were directly incubated at 37°C with rhodamine 123-loaded micelles.Cellular accumula-tion of rhodamine 123was analyzed and results were shown in Fig.3A –C.Incubation of NP-Gal with HepG2cells at 37°C for 4h resulted in increased cell population with high fluorescence (66.2%with log mean fluorescence intensity more than 102),indicating significant micelle internalization and rhodamine 123release.On the contrast,the percentage of cell population with log mean fluorescence intensity more than 102were less than 7%when cells were incubated with NP or NP-Glu,demonstrating only minimal micelles were taken up by HepG2cells without receptor mediation.In the presence of 20mM galactosamine,the uptake of NP-Gal was significantly inhibited,which was char-acterized by the relative GMFI of HepG2cells incubated with orwithout galactosamine (Fig.3D),suggesting that cellular uptake of NP-Gal was mediated by the asialoglycoprotein receptors.Fig.4showed the differential interference contrast (DIC),fluorescence and merged images of HepG2cells after 2h incubation at 37°C with rhodamine-123loaded micelles with or without galactosamine conjugation.The intensity of fluores-cence observed in HepG2cells incubated with NP-Gal markedly increased when compared with that of HepG2cells incubated with non-modified NP.It further confirmed the preponderance of NP-Gal on cellular uptake due to the interaction between galac-tosyl moieties with ASGP-R of HepG2cells.3.5.Delivery of paclitaxel to HepG2cellsPaclitaxel is a highly hydrophobic anticancer drug that has a poor solubility (approximately 1μg/mL in aqueous solution at pH 7.4)[25,26].Amphiphilic block polymers,which self-assemble to nanoparticles in aqueous solution,have been often employed as the vehicle to load paclitaxel into the hydrophobic core for enhanced delivery efficiency [27].In paclitaxel loadingprocedureFig. 3.Flow cytometric analyses of cellular rhodamine 123fluorescence intensity of HepG2cells incubated with galactosamine-conjugated micelles (NP-Gal),glucosamine-conjugated micelles (NP-Glu)or non-modified micelles (NP)at 37°C for 4h (A –C),and the relative geometrical mean fluorescence intensity (GMFI)of HepG2cells cultured with NP-Gal in the absence (−Gal)or presence (+Gal)of 20mM of galactosamine(D).Fig.4.Differential interference contrast (A),fluorescence (B)and merged (C)images of HepG2cells after 2h incubation with non-modified micelles (NP)or galactosamine-conjugated micelles (NP-Gal)at 37°C.Table 1Drug loading efficiency (DLE)and drug loading content (DLC)of micelles prepared at various feeding weight ratios of paclitaxel to block copolymerFeed weight ratio of polymer to PTX DLE (%)DLC (%)10:144.2 4.4220:157.5 2.8750:177.4 1.55200:192.90.4737Y.-C.Wang et al./Journal of Controlled Release 128(2008)32–40。

Elsevier期刊被SCI收录最新一期题录信息本内容包括：主题、各主题有代表性刊名、该刊最新一期目录信息（包括卷期、论文题名、页码及作者等）Automation & Control Systems（自动化及控制系统）SYSTEMS & CONTROL LETTERSVolume 59, Issue 5, Pages 265-322 (May 2010)1.Editorial BoardPage IFC2.Gain-scheduled open-loop system design for LPV systems using polynomially parameter-dependent Lyapunov functionsPages 265-276Masayuki Sato3.Delay-adaptive feedback for linear feedforward systemsPages 277-283Nikolaos Bekiaris-Liberis, Miroslav Krstic4.Implicit Euler numerical scheme and chattering-free implementation of sliding mode systemsPages 284-293Vincent Acary, Bernard Brogliato5.Decentralized dynamic nonlinear controllers to minimize transmit power in cellular networks, Part IPages 294-298Vishwesh V. Kulkarni, Mayuresh V. Kothare, Michael G. Safonov6. ISDS small-gain theorem and construction of ISDS Lyapunov functions for interconnected systemsPages 299-304Sergey Dashkovskiy, Lars Naujok7.An observer for a class of nonlinear systems with time varying observation delay Pages 305-312F. Cacace, A. Germani, C. Manes8.Rendezvous of multiple mobile agents with preserved network connectivity Pages 313-322Housheng Su, Xiaofan Wang, Guanrong ChenBiology（生物学）BIOELECTROCHEMISTRYVolume 79, Issue 1, Pages 1-152 (August 2010)1. Editorial BoardPage IFC2. ContentsPages v-vi3.Electrochemistry of norepinephrine on carbon-coated nickel magnetic nanoparticlesmodified electrode and analytical applicationsPages 1-5Chunli Bian, Qingxiang Zeng, Huayu Xiong, Xiuhua Zhang, Shengfu Wang4.Interaction of surface-attached haemoglobin with hydrophobic anions monitored by on-line acoustic wave detectorPages 6-10Jonathan S. Ellis, Steven Q. Xu, Xiaomeng Wang, Grégoi re Herzog, Damien W.M. Arrigan, Michael Thompson5.Electrochemical impedance spectroscopy of polypyrrole based electrochemical immunosensorPages 11-16A. Ramanavicius, A. Finkelsteinas, H. Cesiulis, A. Ramanaviciene6.Electrochemical and AFM characterization on gold and carbon electrodes of a high redox potential laccase from Fusarium proliferatumPages 17-24K. González Arzola, Y. Gimeno, M.C. Arévalo, M.A. Falcón, A. Hernández Creus7.Improvements in the extraction of cell electric properties from their electrorotation spectrumPages 25-30Damien Voyer, Marie Frénéa-Robin, Franois Buret, Laurent Nicolas8.Electrochemical DNA biosensor for the detection of specific gene related to Trichoderma harzianum speciesPages 31-36Shafiquzzaman Siddiquee, Nor Azah Yusof, Abu Bakar Salleh, Fatimah Abu Bakar, Lee Yook Heng9.Development of electrochemical DNA biosensor based on gold nanoparticle modified electrode by electroless depositionPages 37-42Shufeng Liu, Jing Liu, Li Wang, Feng Zhao10.Herbicides affect fluorescence and electron transfer activity of spinach chloroplasts, thylakoid membranes and isolated Photosystem IIPages 43-49Andrea Ventrella, Lucia Catucci, Angela Agostiano11.Nanostructured polypyrrole-coated anode for sun-powered microbial fuel cells Pages 50-56Yongjin Zou, John Pisciotta, Ilia V. Baskakov12.Anodic oxidation of 3,4-dihydroxyphenylacetic acid on carbon electrodes in acetic acid solutionsPages 57-65Slawomir Michalkiewicz, Agata Skorupa13.A voltammetric Rhodotorula mucilaginosa modified microbial biosensor for Cu(II) determinationPages 66-70Meral Yüce, Hasan Nazır, Gönül Dönmez14.Explore various co-substrates for simultaneous electricity generation and Congo red degradation in air-cathode single-chamber microbial fuel cellPages 71-76Yunqing Cao, Yongyou Hu, Jian Sun, Bin Hou15.Electrochemical oxidation of amphetamine-like drugs and application to electroanalysis of ecstasy in human serumPages 77-83E.M.P.J. Garrido, J.M.P.J. Garrido, N. Milhazes,F. Borges, A.M. Oliveira-Brett16.A l-cysteine sensor based on Pt nanoparticles/poly(o-aminophenol) film on glassy carbon electrodePages 84-89Li-Ping Liu, Zhao-Jing Yin, Zhou-Sheng Yang17.The effects of the electro-photodynamic in vitro treatment on human lung adenocarcinoma cellsPages 90-94Jolanta Saczko, Mariola Nowak, Nina Skolucka, Julita Kulbacka, Malgorzata Kotulska 18.Gadolinium blocks membrane permeabilization induced by nanosecond electric pulses and reduces cell deathPages 95-100Franck M. André, Mikhail A. Rassokhin, Angela M. Bowman, Andrei G. Pakhomov19.Scanning electrochemical microscopy activity mapping of electrodes modified with laccase encapsulated in sol–gel processed matrixPages 101-107Wojciech Nogala, Katarzyna Szot, Malte Burchardt, Martin Jönsson-Niedziolka, Jerzy Rogalski, Gunther Wittstock, Marcin Opallo20.Maltose biosensing based on co-immobilization of α-glucosidase and pyranose oxidasePages 108-113Dilek Odaci, Azmi Telefoncu, Suna Timur21.Plasma membrane permeabilization by trains of ultrashort electric pulses Pages 114-121Bennett L. Ibey, Dustin G. Mixon, Jason A. Payne, Angela Bowman, Karl Sickendick, Gerald J. Wilmink, W. Patrick Roach, Andrei G. Pakhomov22.Effect of nano-topographical features of Ti/TiO2 electrode surface on cell response and electrochemical stability in artificial salivaPages 122-129I. Demetrescu, C. Pirvu, V. Mitran23.Efficiency of the delivery of small charged molecules into cells in vitro Pages 130-135M.S. Venslauskas, S. Šatkauskas, R. Rodaitė-Riševičienė24.Carbon nanotube-enhanced cell electropermeabilisationPages 136-141Vittoria Raffa, Gianni Ciofani, Orazio Vittorio, Virginia Pensabene, Alfred Cuschieri25.Dependence of catalytic activity and long-term stability of enzyme hydrogel films on curing timePages 142-146Joshua Lehr, Bryce E. Williamson, Frédéric Barrière, Alison J. Downard26.Enzymatic flow injection method for rapid determination of choline in urine with electrochemiluminescence detectionPages 147-151Jiye Jin, Masahiro Muroga, Fumiki Takahashi, Toshio NakamuraChemistry Applied（化学应用）CARBOHYDRATE POLYMERSVolume 81, Issue 4, Pages 751-970 (23 July 2010)1.Editorial BoardPage CO22.Adsorption separation of Ni(II) ions by dialdehyde o-phenylenediamine starch from aqueous solutionPages 751-757Ping Zhao, Jian Jiang, Feng-wei Zhang, Wen-feng Zhao, Jun-tao Liu, Rong Li3.Rheological and morphological characterization of the culture broth during exopolysaccharide production by Enterobacter sp.Pages 758-764Vítor D. Alves, Filomena Freitas, Cristiana A.V. Torres, Madalena Cruz, Rodol fo Marques, Christian Grandfils, M.P. Gonçalves, Rui Oliveira, Maria A.M. Reis4.Synthesis and evaluation of N-succinyl-chitosan nanoparticles toward local hydroxycamptothecin deliveryPages 765-768Zhenqing Hou, Jing Han, Chuanming Zhan, Chunxiao Zhou, Quan Hu, Qiqing Zhang5.Synthesis and application of new sizing and finishing additives based on carboxymethyl cellulosePages 769-774Z. El-Sayed Mohamed, A. Amr, Dierk Knittel, Eckhard Schollmeyer6.Synthesis and thermo-physical properties of chitosan/poly(dl-lactide-co-glycolide) composites prepared by thermally induced phase separationPages 775-783Santos Adriana Martel-Estrada, Carlos Alberto Martínez-Pérez, José Guadalupe Chacón-Nava, Perla Elvia García-Casillas, Imelda Olivas-Armendarizparison of the immunological activities of arabinoxylans from wheat bran with alkali and xylanase-aided extractionPages 784-789Sumei Zhou, Xiuzhen Liu, Yan Guo, Qiang Wang, Daiyin Peng, Li Cao8.Nano-in-micro alginate based hybrid particlesPages 790-798Abhijeet Joshi, R. Keerthiprasad, Rahul Dev Jayant, Rohit Srivastava9.The effects of reaction conditions on block copolymerization of chitosan and poly(ethylene glycol)Pages 799-804F. Ganji, M.J. Abdekhodaie10.Thermal behaviour and interactions of cassava starch filled with glycerolplasticized polyvinyl alcohol blendsPages 805-810W.A.W.A. Rahman, Lee Tin Sin, A.R. Rahmat, A.A. Samad11.Banana fibers and microfibrils as lignocellulosic reinforcements in polymer compositesPages 811-819Maha M. Ibrahim, Alain Dufresne, Waleed K. El-Zawawy, Foster A. Agblevor12.Variability of biomass chemical composition and rapid analysis using FT-NIR techniquesPages 820-829Lu Liu, X. Philip Ye, Alvin R. Womac, Shahab Sokhansanj13.TEMPO oxidation of gelatinized potato starch results in acid resistant blocks of glucuronic acid moietiesPages 830-838Ruud ter Haar, Johan W. Timmermans, Ted M. Slaghek, Francisca E.M. Van Dongen, HenkA. Schols, Harry Gruppen14.Development of films based on quinoa (Chenopodium quinoa, Willdenow) starch Pages 839-848Patricia C. Araujo-Farro, G. Podadera, Paulo J.A. Sobral, Florencia C. Menegalli 15.Polysaccharide determination in protein/polysaccharide mixtures for phase-diagram constructionPages 849-854Jacob K. 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Part III: Structures and properties of the Naegeli dextrinsPages 885-891Hongxin Jiang, Sathaporn Srichuwong, Mark Campbell, Jay-lin Jane21.Multistage deacetylation of chitin: Kinetics studyPages 892-896N. Yaghobi, F. Hormozi22.Sulfated modification, characterization and structure–antioxidantrelationships of Artemisia sphaerocephala polysaccharidesPages 897-905Junlong Wang, Hongyun Guo, Ji Zhang, Xiaofang Wang, Baotang Zhao, Jian Yao, Yunpu Wang23.Magnetic chitosan/iron (II, III) oxide nanoparticles prepared by spray-drying Pages 906-910Hsin-Yi Huang, Yeong-Tarng Shieh, Chao-Ming Shih, Yawo-Kuo Twu24.Effect of adding a small amount of high molecular weight polyacrylamide on properties of oxidized cassava starchPages 911-918Yan Liu, Xu-chao Lv, Xiao Hu, Zhi-hua Shan, Pu-xin Zhu25.Preparation of nanofibrillar carbon from chitin nanofibersPages 919-924M. Nogi, F. Kurosaki, H. Yano, M. Takano26.Preparation and characterization of cellulose acetate–Fe2O3 composite nanofibrous materialsPages 925-930Costas Tsioptsias, Kyriaki G. Sakellariou, Ioannis Tsivintzelis, Lambrini Papadopoulou, Costas Panayiotou27.Synthesis, characteristic and antibacterial activity of N,N,N-trimethyl chitosan and its carboxymethyl derivativesPages 931-936Tao Xu, Meihua Xin, Mingchun Li, Huili Huang, Shengquan Zhou28.Fast compositional analysis of ramie using near-infrared spectroscopyPages 937-941Wei Jiang, Guangting Han, Yuanming Zhang, Mengmeng Wang29.Structure characterization of polysaccharide isolated from the fruiting bodies of Tricholoma matsutakePages 942-947Xiang Ding, Su Feng, Mei Cao, Mao-tao Li, Jie Tang, Chun-xiao Guo, Jie Zhang, Qun Sun, Zhi-rong Yang, Jian Zhao30.New insights into viscosity abnormality of sodium alginate aqueous solution Pages 948-952Dan Zhong, Xin Huang, Hu Yang, Rongshi Cheng31.Structural characterization and anti-inflammatory activity of two water-soluble polysaccharides from Bellamya purificataPages 953-960Hong Zhang, Lin Ye, Kuiwu WangComputer Science, Artificial Intelligence（计算机科学，人工智能）ARTIFICIAL INTELLIGENCEVolume 174, Issue 11, Pages 639-766 (July 2010)1.Editorial BoardPage IFC2.Partial observability and learnabilityPages 639-669Loizos Michael3.Monte Carlo tree search in KriegspielPages 670-684Paolo Ciancarini, Gian Piero Favini4.Learning conditional preference networksPages 685-703Frédéric Koriche, Bruno Zanuttini5.Planning to see: A hierarchical approach to planning visual actions on a robot using POMDPsPages 704-725Mohan Sridharan, Jeremy Wyatt, Richard Dearden6.Analysis of a probabilistic model of redundancy in unsupervised information extractionPages 726-748Doug Downey, Oren Etzioni, Stephen Soderland7. Designing competitions between teams of individualsPages 749-766Pingzhong Tang, Yoav Shoham, Fangzhen LinEnergy & Fuels（能源和燃料）APPLIED ENERGYVolume 87, Issue 8, Pages 2427-2768 (August 2010)1.IFCPage IFC2. Energy balance analysis of wind-based pumped hydro storage systems in remote island electrical networksPages 2427-2437J.K. Kaldellis, M. Kapsali, K.A. Kavadias3.Energy auditing and energy conservation potential for glass worksPages 2438-2446Yingjian Li, Jiezhi Li, Qi Qiu, Yafei Xu4.Energy demand and comparison of current defrosting technologies of frozen raw materials in defrosting tunnelsPages 2447-2454Marek Bezovsky, Michal Stricik, Maria Prascakova5.Guidelines for clockspeed acceleration in the US natural gas transmission industry Pages 2455-2466Ruud Weijermars6.Multi-objective self-adaptive algorithm for highly constrained problems: Novel method and applicationsPages 2467-2478Abdelaziz Hammache, Marzouk Benali, François Aubé7.Stochastic interest rates in the analysis of energy investments: Implications on economic performance and sustainabilityPages 2479-2490Athanasios Tolis, Aggelos Doukelis, Ilias Tatsiopoulos8.Effects of the PWM carrier signals synchronization on the DC-link current in back-to-back convertersPages 2491-2499L.G. González, G. Garcerá, E. Figueres, R. González9.Efficiency improvement of the DSSCs by building the carbon black as bridge in photoelectrodePages 2500-2505Chen-Ching Ting, Wei-Shi Chao10.Integer programming with random-boundary intervals for planning municipal power systemsPages 2506-2516M.F. Cao, G.H. Huang, Q.G. Lin11. Modeling the relationship between the oil price and global food prices Pages 2517-2525Sheng-Tung Chen, Hsiao-I Kuo, Chi-Chung Chen12.Marginal production in the Gulf of Mexico – II. Model resultsPages 2526-2534Mark J. Kaiser, Yunke Yu13.Marginal production in the Gulf of Mexico – I. Historical statistics & model frameworkPages 2535-2550Mark J. Kaiser14.Assessment of forest biomass for use as energy. GIS-based analysis of geographical availability and locations of wood-fired power plants in PortugalPages 2551-2560H. Viana, Warren B. Cohen, D. Lopes, J. Aranha15.Alkaline catalyzed biodiesel production from moringa oleifera oil with optimized production parametersPages 2561-2565G. Kafuku, M. 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Journal of Hazardous Materials 182 (2010) 156–161Contents lists available at ScienceDirectJournal of HazardousMaterialsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j h a z m atAs(III)removal using an iron-impregnated chitosan sorbentDaniel Dianchen Gang a ,∗,Baolin Deng b ,LianShin Lin caDepartment of Civil Engineering,University of Louisiana at Lafayette,Lafayette,LA 70504,USAbDepartment of Civil and Environmental Engineering,University of Missouri,Columbia,MO 65211,USA cDepartment of Civil and Environmental Engineering,West Virginia University,Morgantown,WV 26506,USAa r t i c l e i n f o Article history:Received 18December 2009Received in revised form 28May 2010Accepted 1June 2010Available online 9 June 2010Keywords:Trivalent arsenic Iron-chitosan AdsorptionAs(III)adsorption kinetics Adsorption isotherma b s t r a c tAn iron-impregnated chitosan granular adsorbent was newly developed to evaluate its ability to remove arsenic from water.Since most existing arsenic removal technologies are effective in removing As(V)(arsenate),this study focused on As(III).The adsorption behavior of As(III)onto the iron-impregnated chi-tosan absorbent was examined by conducting batch and column studies.Maximum adsorption capacity reached 6.48mg g −1at pH =8with initial As(III)concentration of 1007␮g L −1.The adsorption isotherm data fit well with the Freundlich model.Seven hundred and sixty eight (768)empty bed volumes (EBV)of 308␮g L −1of As(III)solution were treated in column experiments.These are higher than the empty bed volumes (EBV)treated using iron-chitosan composites as reported by previous researchers.The investi-gation has indicated that the iron-impregnated chitosan is a very promising material for As(III)removal from water.© 2010 Elsevier B.V. All rights reserved.1.IntroductionArsenic,resulting from industrial and mine waste discharges or from natural erosion of arsenic containing rocks,is found in many surface and ground waters [1].Common chemical forms of arsenic in the environment include arsenate (As(V)),arsenite (As(III)),dimethylarsinic acid (DMA),and monomethylarsenic acid (MMA).Inorganic forms of arsenic (As(V)and As(III))are more toxic than the organic forms [2].Arsenite can be predominant in ground-water with low oxygen levels and is generally more difficult to be removed than arsenate [3].Due to the negative impacts of arsenic on human health that range from acute lethality to chronic and car-cinogenic effects,the U.S.Environmental Protection Agency revised the maximum contaminant level (MCL)of arsenic in drinking water from 50to 10␮g L −1[4].This new regulation has posed a chal-lenge for the research of new technologies capable of selectively removing low levels of arsenic.Existing technologies that are being used for arsenic removal include precipitation [5],membrane separation,ion exchange,and adsorption [6–9].While these approaches can remove arsenic to below 10␮g L −1under optimal conditions,most of the systems are expensive,not suitable for small communities with limited resources.Of these methods,much work has been done on arsenic removal through adsorption because it is one of the most effec-∗Corresponding author.Tel.:+13374825184;fax:+13374826688.E-mail addresses:ddgang@ ,digang@ ,Gang@ (D.D.Gang).tive and inexpensive methods for arsenic treatment [7].Therefore,development of highly effective adsorbents is a key for adsorption-based technologies.Several iron(III)oxides,such as amorphous hydrous ferric oxide [5]and crystalline hydrous ferric oxide [10]are well known for their ability to remove both As(V)and As(III)from aqueous solutions.In general,arsenate is more readily removed by ferric (hydr)oxides than arsenite [11].Reported mechanisms for arsenic removal include adsorption onto the hydroxide surfaces,entrapment of adsorbed arsenic in the flocculants,and formation of complexes and ferric arsenate (FeAsO 4)[12].The presence of other anions such as sulfate,chloride,and in particular,silicates,phosphate,and natural organic matters,can significantly affect arsenic adsorption [13–15].The use of iron (hydr)oxides in fine powdered or amor-phous forms was found to be effective for arsenic removal,but the process requires follow-up solid/water separation.For packed-bed adsorption systems,high-efficient granular forms of adsorbent are essential.Recently,several iron based granular materials and processes have been developed for arsenic removal.Dong et al.[16]devel-oped iron coated pottery granules (ICPG)for both As(III)and As(V)removal from drinking water.The column tests showed that ICPG consistently removed total arsenic from test water to below 5␮g L −1level.In another study,Gu et al.[17]used iron-containing granular activated carbon for arsenic adsorption.This iron-containing granular activated carbon was shown to remove arsenic most efficiently when the iron content was approximately 6%.Viraraghavan et al.[18]reported a green sand filtration process and found a strong correlation between influent Fe(II)concen-0304-3894/$–see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.jhazmat.2010.06.008D.D.Gang et al./Journal of Hazardous Materials182 (2010) 156–161157tration and arsenic removal percentage.The removal percentage increased from41%to above80%as the ratio of Fe/As was increased from0to20.Granular ferric hydroxide(GFH),another iron based granular material,showed a high treatment capacity for arsenic removal in a column setting before the breakthrough concentration reached10␮g L−1[19].It was found that complexes were formed upon the adsorption of arsenate on GFH[20].Selvin et al.[21]con-ducted laboratory-scale tests over50different media for arsenic removal and found GFH with a particle size of0.8–2.0mm was the most effective one among the tested media.However,some disad-vantages with GFH exist,including quick head loss buildup within 2days because of thefine particle size,and significant reduction (50%)in adsorption capacity with larger sized media(1.0–2.0mm).Chitin and its deacetylated product,chitosan,are the world’s second most abundant natural polymers after cellulose.These polymers contain primary amino groups,which are useful for chemical modifications and can be used as potential separa-tors in water treatment and other industrial applications.Many researchers focused on chitosan as an adsorbent because of its non-toxicity,chelating ability with metals,and biodegradability[22]. Several studies have demonstrated that chitosan and its deriva-tives could be used to remove arsenic from aqueous solutions [23,24].Based on the fact that both iron(III)oxides and chitosan exhib-ited high affinity for arsenic,this study focused on examining the effectiveness of an iron-impregnated chitosan granular adsorbent for arsenic removal.Most arsenic removal technologies are more effective for removing arsenate than for arsenite[12].We found in this study that the iron-impregnated chitosan was effective for arsenite removal from experiments in both batch and column set-tings.2.Experimental2.1.Preparation of iron-chitosan beadsThe experimental procedure for the preparation of iron-chitosan beads was described in detail by Vasireddy[25].To summarize, approximately10g of medium molecular weight chitosan(Aldrich Chemical Corporation,Wisconsin,USA)was added to0.5L of0.01N Fe(NO3)3·9H2O solution under continuous stirring at60◦C for2h to form a viscous gel.The beads were formed by drop-wise addition of chitosan gel into a0.5M NaOH precipitation bath under room temperature.Maintaining this concentration of NaOH was critical for forming spherically shaped beads[25].The beads were then separated from the0.5M NaOH solution and washed several times with deionized water to a neutral pH.The wet beads were then dried in an oven under vacuum and in air.Thefinal iron content of the chitosan bead was about8.4%.2.2.Arsenic measurementAn atomic absorption spectrometer(AAS)(Thermo Electron Corporation)equipped with an arsenic hollow cathode lamp was employed to measure arsenic concentration.An automatic inter-mittent hydride generation device was used to convert arsenic in water samples to arsenic hydride.The hydrides were then purged continuously by argon gas into the atomizer of an atomic absorption spectrometer for concentration measurements.As(III)stock solution(1000mg L−1)was prepared by dissolving 1.32g of As2O3(obtained from J.T.Baker)in distilled water con-taining4g NaOH,which was then neutralized to pH about7with 1%HCl and diluted to1L with distilled water.All the working solu-tions were prepared with standard stock solution.To50mL of each sample solution(i.e.,reagent blank,standard solutions,and water samples),5mL1%HCl and5mL of100g L−1NaI solution were used to convert arsenic in water samples to arsenic hydride.2.3.Arsenic adsorption experimentsEach arsenic solution(100mL)of desired concentration was mixed with the iron-chitosan beads in a250mL conicalflask.The solution pH was adjusted with0.1M HCl or0.1M NaOH to obtain the desired pHs.A pH buffer was not used to avoid potential com-petition of buffer with As(III)sorption.One sample of the same concentration solution without adsorbent(blank),used to estab-lish the initial concentration of the samples,was also treated under same conditions as the samples containing the adsorbent.The solu-tions were placed in a shaker for afixed amount time,followed by filtration to remove the adsorbent.Thefiltrate was then analyzed for thefinal concentration of arsenic using the atomic absorption spectrometer.The solid phase concentration was calculated using the following formula:q=(C i−C f)VM(1) where,q(␮g g−1)is the solid phase concentration,C i(␮g L−1)is the initial concentration of arsenic in solution,C f(␮g L−1)is thefinal concentration of arsenic in treated solution;V(L)is the volume of the solution,and M(g)is the weight of the iron-chitosan adsorbent.2.4.Kinetic experimentsAdsorption kinetics was examined with various initial concen-trations at25◦C.The pH of the solutions was chosen at8.0for optimal adsorption.The adsorbent loading for three different ini-tial concentrations of306,584,and994␮g L−1was all0.2g L−1.A predetermined quantity of iron-chitosan adsorbent(20mg)was placed in separate conicalflasks with pH-adjusted As(III)solution. The conicalflasks were covered with parafilm and placed in a shaker (150rpm),and sub-samples of the solutions were then removed periodically andfiltered prior to arsenic analysis.To determine the reaction rate constants of arsenic adsorption onto iron-chitosan,both the pseudo-first-order and pseudo-second-order models were used.Kinetics of the pseudo-first-order model can be expressed as[26]:ln(q e−q t)=ln q e−k1t(2) where,k1(min−1)is the rate constant of pseudo-first-order adsorp-tion,q t(mg g−1)is the amount of As(III)adsorbed at time t(min), and q e(mg g−1)is the amount of adsorption at equilibrium.The model parameters k1and q e can be estimated from the slope and intercept of the plot of ln(q e−q t)vs t.The pseudo-second-order model can be expressed as follow[27]:tq t=tq e+1k2q2e(3)where,k2(g mg−1min−1)is the pseudo-second-order reaction rate. Parameters k2and q e can be estimated from the intercept and slope of the plot of(t/q t)vs t.2.5.Isotherm modelsAdsorption isotherms such as the Freundlich or Langmuir mod-els are commonly utilized to describe adsorption equilibrium.The Freundlich isotherm model is represented mathematically as:q e=k f C1/ne(4) where,q e(mg g−1)is the amount of As(III)adsorbed,C e(␮g L−1) is the concentration of arsenite in solution(␮g L−1),k f and1/n158 D.D.Gang et al./Journal of Hazardous Materials182 (2010) 156–161Fig.1.Scanning electron micrograph(SEM)of iron-chitosan bead.are parameters of the Freundlich isotherm,denoting a distribu-tion coefficient(L g−1)and intensity of adsorption,respectively.The Langmuir equation is another widely used equilibrium adsorption model.It has the advantage of providing a maximum adsorption capacity q max(mg g−1)that can be correlated to adsorption proper-ties.The Langmuir model can be represented as:q e=q maxK L C e1+K L C e(5)where,q max(mg g−1)and K L(L mg−1)are Langmuir constants representing maximum adsorption capacity and binding energy, respectively.2.6.Column studyColumn study was conducted to investigate the use of iron-chitosan as a low-cost treatment technology for arsenite removal. Experiments were conducted with a12-mm-ID glass column packed with1.5g iron-chitosan as afixed bed.The influent solu-tion had an inlet As(III)concentration of308␮g L−1at pH8,and was passed the column at aflow rate of25mL h−1.Effluent solu-tion samples were collected and analyzed for arsenic concentration during the column test.3.Results and discussion3.1.Structure characterization of iron-chitosan beadsThe prepared iron-chitosan beads were examined by scanning electron microscope(SEM)(AMRAY1600)for the surface morphol-ogy.A working distance of5–10mm,spot size of2–3,secondary electron(SE)mode,and accelerating voltage of20keV were used to view the samples.It can be seen from Fig.1that the beads are porous in structure.X-ray Photoelectron Spectroscopy(XPS),a sur-face sensitive analytic tool to determine the surface composition and electronic state of a sample,was used in this study.In XPS analysis,a survey scan was used to determine the elements exist-ing on the surface.The high resolution utility scans were then used to measure the atomic concentrations of Fe,C,N and O in the sam-ple.Fig.2shows the peak positions of carbon,nitrogen,oxygen,and iron obtained by the XPS for iron-chitosan beads.In Fig.2,the car-bon1s peak was observed at283.0eV with a FWHM(full width at maximum height)of2.015.The Fe peak was observed at730.0eV. The N-1s peak for iron-chitosan bead was found at398.0eV(FWHM 2.00eV),which can be attributed to the amino groups inchitosan.Fig.2.XPS spectrum of iron-chitosan bead.3.2.Effect of pHThe effect of pH on arsenite removal with the iron-chitosan adsorbent was examined using100mL As(III)solution with an initial concentration of314␮g L−1and a solid loading rate of 0.15g L−1.The solution pH was adjusted with0.1M HCl or0.1M NaOH to obtain pHs ranging from4to12.Lower pHs were avoided because the acid environments could lead to partial dissolution of the chitosan polymer and make the beads unstable[25,28]. The solutions were placed in a shaker(150rpm)for20h at room temperature(25◦C),followed byfiltration to remove the adsor-bent.The amounts of As(III)adsorbed,calculated using Eq.(1),are present in Fig.3.Under the experimental conditions,approximately 2.0mg g−1of As(III)was adsorbed and that amount did not change significantly in the pH range4–9.However,when pH was higher than9.2,arsenite removal decreased dramatically with increasing pH.The results can be explained using arsenic chemical speciation in different pH ranges[29].Arsenite remains mostly as a neutral molecule for pH<9.2,and negatively charged at pH>9.2.So at pH>9.2,arsenite sorption is less because of the unfavorable electro-static interaction with negatively charged surfaces.This adsorptive behavior is common for arsenite with other adsorbents[17,30].Gu et al.[17]reported that pH had no obvious effect on As(III)removal in the range of4.4–9.0,with removal efficiency above95%.Another study indicated that the uptake of As(III)by fresh andimmobi-Fig.3.Arsenite removal of the iron-chitosan adsorbent(0.15g L−1)as a function of pH for initial arsenite concentration of314␮g L−1at T=25◦C.D.D.Gang et al./Journal of Hazardous Materials182 (2010) 156–161159Fig.4.Adsorption kinetics for different initial arsenite concentrations with iron-chitosan adsorbent loading of0.2g L−1at pH=8and T=25◦C.lized biomass was not greatly affected by solution pH with optimal biosorption occurring at around pH6–8[30].Raven et al.[11] reported that a maximum adsorption of arsenite on ferrihydrite was observed at approximately pH9.3.3.Kinetics of adsorptionFig.4illustrates the adsorption kinetics for three different ini-tial arsenite concentrations.More than60%of the arsenite was adsorbed by iron-chitosan within thefirst30min,then adsorption leveled off after2h.Given the initial concentrations and adsorbent loading,equilibrium was reached after about2h.The adsorption capacity increased from1.51to4.60mg g−1as the initial arsen-ite concentration was increased from306to994␮g L−1.The rapid adsorption in the beginning can be attributed to the greater con-centration gradient and more available sites for adsorption.This is a common behavior with adsorption processes and has been reported in other studies[31].The sorption rate of As(III)on nat-urally available red soil was initially rapid in thefirst2h and slowed down thereafter[32].Elkhatib et al.[33]reported that the initial adsorption was rapid,with more than50%of As(III) adsorbed during thefirst0.5h in an arsenite adsorption study. Fuller et al.[34]reported that As(V)adsorption onto synthesized ferrihydrite had a rapid initial phase(<5min)and adsorption con-tinued for182h.Raven et al.[11]studied the kinetics of As(V) and As(III)adsorption on ferrihydrite and found that most of the adsorption occurred within thefirst2h.It has been reported that arsenite forms both inner-and outer-sphere surface complexes on amorphous Fe oxide[35].Another possible adsorption mech-anism is hydrogen bond formation between As(III)and chitosan bead[24].Figs.5and6illustrate modelfits of the kinetic data for the pseudo-first-order and pseudo-second-order kinetic models. In general,the pseudo-second-order characterized the kinetic data better than the pseudo-first-order model.Table1summa-Fig.5.Adsorption kinetics of the iron-chitosan adsorbent(0.2g L−1)for three initial arsenite concentrations at pH=8and T=25◦C,and corresponding pseudo-first-ordermodels.Fig.6.Adsorption kinetics of the iron-chitosan adsorbent(0.2g L−1)for three initial arsenite concentrations at pH=8and T=25◦C,and corresponding pseudo-second-order models.rizes adsorption capacities determined from the modelfits.It is noted that the second order rate constant(k2)decreased from 3.19×10−2to 1.15×10−2g mg−1min−1as the initial concen-tration increased from306to994␮g L−1.The initial rate(k2q2e) increased from8.48×10−2to27.97×10−2with increasing initial As(III)concentration.Because as initial concentration increased,the concentration difference between the adsorbent surface and bulk solution increased.Jimenez-Cedillo et al.[36]investigated arsenic adsorp-tion kinetics on iron,manganese and iron-manganese-modified clinoptilolite-rich tuffs and concluded that the adsorption pro-cesses could be described by the pseudo-second-order model.Table1Adsorption capacities and parameter values of kinetic models for three initial arsenite concentrations and iron-chitosan loading of0.2g L−1at pH=8.Initial conc.(␮g L−1)Pseudo-first order Pseudo-second orderk1×102(min−1)R2q e,exp(mg g−1)q e,col(mg g−1)k1×102(g mg−1min−1)R2q e,exp(mg g−1)q e,col(mg g−1)k2q2e×102306 2.630.98 1.51 1.24 3.190.99 1.51 1.638.48584 2.380.96 2.90 2.30 1.310.99 2.90 3.1913.28994 2.370.93 4.60 3.26 1.150.99 4.60 4.9327.97160 D.D.Gang et al./Journal of Hazardous Materials182 (2010) 156–161Fig.7.Adsorption isotherms of the iron-chitosan adsorbent (0.2g L −1)for three initial arsenite concentrations at pH =8,and corresponding isotherm models.Thirunavukkarasu et al.[37]examined As(III)adsorption kinet-ics with granular ferric hydroxide (GFH)and found that most of As(III)adsorption onto GFH occurred at pH 7.6,with 68%of As(III)removed within 1h and 97%removed at the equilibrium time of 6h.Kinetic data fitted the pseudo-second-order kinetic model well with a kinetic rate constant of 0.003g GFH h −1␮g −1As,which is equivalent to 5.0×10−2g mg −1min −1[37].In our study,the kinetic rate constants were from 3.19×10−2to 1.15×10−2g mg −1min −1,which were smaller than using GFH.This could be attributed to the differences in adsorbent parti-cle size and initial arsenic concentrations between these two studies.3.4.Adsorption isothermsFig.7presents the adsorption isotherm data and two isotherm models at pH 8.The maximum adsorption capacity was found to increase from 1.97to 6.48mg g −1as the initial concentration of As(III)increased from 295to 1007␮g L −1.Maximum adsorp-tion capacity reached 6.48mg g −1with initial As(III)concentration of 1007␮g L −1.Chen and Chung [24]reported that the adsorp-tion capacity of As(III)was 1.83mg As g −1for pure chitosan bead.This study confirmed that impregnating iron into chitosan could significantly increase the As(III)adsorption capacity of the chi-tosan bead.In another study,Driehaus et al.[19]reported that the adsorption capacity could reach 8.5mg As g −1of granular fer-ric hydroxide (GFH).Model parameters and regression coefficients are listed in Table 2.The Freundlich model agreed better with the experimental data compared to the Langmuir model.The adsorp-tion intensity (1/n )and the distribution coefficient (k f )increased as the initial arsenite concentration increased.This indicated the dependence of adsorption on initial concentration.Low 1/n values (<1)of the Freundlich isotherm suggested that any large change in the equilibrium concentration of arsenic would not result in a significant change in the amount of arsenic adsorbed.Selim and Zhang [38]reported that adsorption isotherms of three differ-ent soils for As(V)were better fit to the Freundlich modelandFig.8.Breakthrough curve for an inlet arsenite concentration of 308␮g L −1at pH =8for a column reactor packed with the iron-chitosan adsorbent.adsorption intensity values ranged from 0.270to 0.340.Salim and Munekage [39]found that adsorptions of As(III)onto silica ceramic were well fit by the Freundlich isotherm.Similarly low 1/n values for As(V)adsorption have been reported by others [40].3.5.Column studyFig.8shows a breakthrough curve for an inlet arsenite con-centration of 308␮g L −1at pH 8.The break point was observed after 768empty bed volumes (EBV)and adsorbent was exhausted at 1400bed volumes.In comparison,Boddu et al.[23]reported that the break through point was about 40and 120EBV for As(III)and As(V),respectively using chitosan-coated biosorbent.Gupta et al.[41]conducted column tests using iron-chitosan compos-ites for removal of As(III)and As(V)from arsenic contaminated real life groundwater.Their result showed that the iron-chitosan flakes (ICF)could treat 147EBV of As(III)and 112EBV of As(V)spiked groundwater with an As(III)or As(V)concentration of 0.5mg L −1.Given the difference of the initial concentrations between the two studies,the numbers of EBV were lower than what we found in this study.This can be partially attributed to the difference of the water constituents in the real grounder water used in the previous study [41].Gu et al.[17]examined the arsenic breakthrough behaviors for an As-GAC sample prepared from Dacro 20×40LI with an inlet concentration of 56.1␮g L −1As(III).Their results demonstrated that the adsorbent could effectively remove arsenic from ground-water in a column setting.Dong et al.[16]also reported that average removal efficiencies for total arsenic,As(III),and As(V)for a 2-week test period were 98%,97%,and 99%,respectively,at an average flow rate of 4.1L h −1and Empty Bed Contact Time (EBCT)>3min.Table 2Values of the Freundlich and Langmuir isotherm model parameters for three arsenite concentrations with iron-chitosan loading of 0.2g L −1at pH 8.Initial concentration(␮g L −1)Freundlich parameters Longmuir constants k f (L g −1)1/n R 2q max (mg g −1)K L (L mg −1)R 22950.590.240.98 2.000.120.985960.640.260.95 2.820.070.9410070.740.330.996.820.010.95D.D.Gang et al./Journal of Hazardous Materials182 (2010) 156–1611614.ConclusionsOverall,the study has demonstrated that iron-impregnated chi-tosan can effectively remove As(III)from aqueous solutions under a wide range of experimental conditions and removal efficiency depends on various factors including pH,adsorption time,adsor-bent loading,and initial concentration of As(III)in the solution. Results from the kinetic batch experiments indicated that more than60%of the arsenic was adsorbed by the iron-chitosan within 30min of adsorption.Kinetic resultsfit the pseudo-second-order model well.The second order reaction rate constants were found to decrease from3.19×10−2to1.15×10−2g mg−1min−1as the initial As(III)concentration increased from306to994␮g L−1.Adsorp-tion isotherm results indicated that maximum adsorption capacity increased from1.97to6.48mg g−1at pH=8as the initial concen-tration of As(III)increased from0.3to1mg L−1.The adsorption isotherm datafit well to the Freundlich model.Column experi-ments of As(III)removal were conducted using12-mm-ID column at aflow rate of25mL h−1with an initial As(III)concentration of 308␮g L−1.This study corroborates that impregnating iron into chitosan can significantly increase As(III)adsorption capacity of the chitosan bead.Advantages of using the iron-impregnated chitosan include its high efficiency for As(III)treatment and low cost compared with the pure chitosan bead.We expect that the iron-impregnated chi-tosan is a useful adsorbent for As(III)and could be used both in conventional packed-bedfiltration tower and Point of Use(POU) systems.The possible concerns include the physicochemical sta-bility of the adsorbent because of the biodegradable nature of the chitosan material.Further research is underway to examine the adsorbent stability and whether the iron-impregnated chitosan can maintain its capability after several regeneration andCompeting adsorption of other ions will also be AcknowledgmentsThe authors would like to thank Mr.Ravi K.Kadari and Ms. Dhanarekha Vasireddy for conducting the laboratory experiments. 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Vol 136No 112・26・化　工　新　型　材　料N EW CH EMICAL MA TERIAL S 第36卷第12期2008年12月新材料与新技术基金项目:国家自然科学基金(20476065;20736004);国家教委留学回国基金;中国科学院过程工程研究所多相反应国家重点实验室基金(200322);中国科学院煤炭化学研究所煤转化国家重点实验室基金(20062902);合成化学江苏省重点实验室基金;苏州大学基础课化学实验教学中心;南京医科大学研发基金(N Y0586)作者简介:冯斌(1984-),男,硕士研究生,应用化学专业,研究方向磁性功能材料。

32氨丙基三乙氧基硅烷表面修饰的磁性Fe 3O 4纳米粒子合成与表征冯　斌1　任志强1　屈晶苗1　洪若瑜1,2　李洪钟2　魏东光3(1.苏州大学化学化工学院,江苏省有机合成重点实验室,苏州215123;2.中科院过程工程研究所多相反应国家重点实验室,北京100080;3.哈佛大学工程与应用科学学院,纳米尺寸研究中心,马萨诸塞州02139.)摘　要　以FeCl 3、FeSO 4为铁源,利用改进共沉淀法合成磁性纳米Fe 3O 4,在其制备的过程中加入水合肼充当还原剂和沉淀剂,采用32氨丙基三乙氧基硅烷(A PTES ),通过硅烷化反应以化学键的方式结合Fe 3O 4纳米颗粒,获得表面氨基化的磁性Fe 3O 4纳米复合颗粒。

并用XRD 、IR 、TEM 、VSM 等分析手段深入研究了AP TES 修饰前后磁性纳米颗粒结构和性能影响。

结果表明A PTES 成功包覆到磁性纳米粒子表面,其包覆率为21%;磁性颗粒粒径为20nm ,晶型为反立方尖晶石型;磁性颗粒具有很好的分散性,其磁化率为2.36×10-6,饱和磁化强度达60.8mT 。

关键词　磁性纳米颗粒,共沉淀法,表面修饰,氨基化Preparation and characterization of (32aminopropyl)triethoxysilane coatedmagnetite nanoparticlesFeng Bin 1　Ren Zhiqiang 1　Qu Jingmiao 1　Hong Ruoyu 1,2　Li Hongzhong 2　Wei Dongguang 3(11Chem.Eng.Dept.&Key Lab.of Organic Synt hesis of Jiangsu Prov.,Soochow Univ.,SIP ,Suzhou 215123;21State Key Lab.of Multip hase Reactio n ,Inst.of Proc.Eng.,Chinese Academy of Sciences ,Beijing 100080;31Center for Nanoscale Sys.,School of Eng.&Appl.Sci.,Harvard Univ.,11Oxford St.,Cambridge ,MA 02139)Abstract Using FeCl 3and FeSO 4as iron sources ,Fe 3O 4magnetic nanoparticles were synthesized by modifiedchemical co 2precipitation.Hydrazine hydrate as reducing agent and precipitator was added in the process of preparation.Magnetite nanoparticles coated with (32aminopropyl )triethoxysilane ,were prepared by silanization reaction and character 2ized by XRD ,TEM ,IR ,VSM et al.The result showed that nanoparticles were coated successf ully by A PTES ,the coat 2ing percentage was about 21%,the mean size of the magnetic nanoparticles were about 20nm ,and their morphology was inverse spinel.The A PTES coated magnetite nanoparticles demonstrated excellent dispersibility ,and had susceptibility of 2136×10-6and saturation magnetization of 6018m T.K ey w ords magnetite nanoparticle ,coprecipitation ,surface modification ,amino 2functionalization 纳米材料,特别是磁性纳米粒,是物理、化学、化工、材料科学与工程和生物医药等领域研究的热点[125]。

ARTICLEOPENReceived11Dec2012|Accepted16May2013|Published14Jun2013A solid with a hierarchical tetramodalmicro-meso-macro pore size distributionYu Ren1,Zhen Ma2,3,Russell E.Morris1,Zheng Liu1,Feng Jiao4,Sheng Dai3&Peter G.Bruce1Porous solids have an important role in addressing some of the major energy-related pro-blems facing society.Here we describe a porous solid,a-MnO2,with a hierarchical tetramodalpore size distribution spanning the micro-,meso-and macro pore range,centred at0.48,4.0,18and70nm.The hierarchical tetramodal structure is generated by the presence ofpotassium ions in the precursor solution within the channels of the porous silica template;thesize of the potassium ion templates the microporosity of a-MnO2,whereas theirreactivity with silica leads to larger mesopores and macroporosity,without destroying themesostructure of the template.The hierarchical tetramodal pore size distribution influencesthe properties of a-MnO2as a cathode in lithium batteries and as a catalyst,changingthe behaviour,compared with its counterparts with only micropores or bimodalmicro/mesopores.The approach has been extended to the preparation of LiMn2O4with ahierarchical pore structure.1EaStCHEM,School of Chemistry,University of St Andrews,St Andrews KY169ST,UK.2Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3),Department of Environmental Science and Engineering,Fudan University,Shanghai200433,China.3Chemical Sciences Division,Oak Ridge National Laboratory,Oak Ridge,T ennessee37831,USA.4Department of Chemical and Biomolecular Engineering,University of Delaware,Newark,Delaware19716,USA.Correspondence and requests for materials should be addressed to P.G.B.(email:p.g.bruce@).P orous solids have an important role in addressing some of the major problems facing society in the twenty-first century,such as energy storage,CO2sequestration,H2 storage,therapeutics(for example,drug delivery)and catalysis1–8. The size of the pores and their distribution directly affect their ability to function in a particular application2.For example, zeolites are used as acid catalysts in industry,but their micropores impose severe diffusion limitations on the ingress and egress of the reactants and the catalysed products9.To address such issues, great effort is being expended in preparing porous materials with a bimodal(micro and meso)pore structure by synthesizing zeolites or silicas containing micropores and mesopores10–17,or microporous metal–organic frameworks with ordered mesopores18.Among porous solids,porous transition metal oxides are particularly important,because they exhibit many unique properties due to their d-electrons and the variable redox state of their internal surfaces8,19–22.Here we describe thefirst solid(a-MnO2)possessing hierarchical pores spanning the micro,meso and macro range, centred at0.48,4.0,18and70nm.The synthesis method uses mesoporous silica as a hard template.Normally such a template generates a mesoporous solid with a unimodal23–31or,at most,a bimodal pore size distribution32–38.By incorporating Kþions in the precursor solution,within the silica template,the Kþions act bifunctionally:their size templates the formation of the micropores in a-MnO2,whereas their reactivity with silica destroys the microporous channels in KIT-6comprehensively, leading to the formation of a-MnO2containing large mesopores and,importantly,macropores,something that has not been possible by other methods.Significantly,this is achieved without destroying the silica template by alkaline ions.The effect of the tetramodal pore structure on the properties of the material is exemplified by considering their use as electrodes for lithium-ion batteries and as a catalyst for CO oxidation and N2O decomposition.The novel material offers new possibilities for combining the selectivity of small pores with the transport advantages of the large pores across a wide range of sizes.We also present results demonstrating the extension of the method to the synthesis of LiMn2O4with a hierarchical pore structure.ResultsComposition of tetramodal a-MnO2.The composition of the synthesized material was determined by atomic absorption ana-lysis and redox titration to be K0.08MnO2(the K/Mn ratio of the precursor solution was1/3).The material is commonly referred to as a-MnO2,because of the small content of Kþ19.N2sorption analysis of tetramodal a-MnO2.The tetramodal a-MnO2shows a type IV isotherm(Fig.1a).The pore size dis-tribution(Fig.1b)in the range of0.3–200nm was analysed using the density functional theory(DFT)method applied to the adsorption branch of the isotherm39–42,as this is more reliable than analysing the desorption branch43;note that this is not the DFT method used in ab initio electronic structure calculations. Plots were constructed with vertical axes representing ‘incremental pore volume’and‘incremental surface area’.Large (macro)pores can account for a significant pore volume while representing a relatively smaller surface area and vice versa for small(micro)pores.Therefore,when investigating a porous material with a wide range of pore sizes,for example,micropore and macropore,the combination of surface area and pore volume is essential to determine the pore size distribution satisfactorily (Fig.1b).Considering both pore volume and surface area, significant proportions of micro-,meso-and macropores are evident,with distinct maxima centred at0.70,4.0,18and70nm.To probe the size of the micropores more precisely than is possible with DFT,the Horvath–Kawazoe pore size distribution analysis was employed44.A single peak was obtained at0.48nm(Fig.1c),in good accord with the0.46-nm size of the2Â2channels of a-MnO2 (refs.19,21).The relatively small Brunauer–Emmett–Teller(BET) surface area of tetramodal a-MnO2(79–105m2gÀ1; Supplementary Table S1)compared with typical surface areas of mesoporous metal oxides(90–150m2gÀ1)45is due to the significant proportion of macropores(which have small surface areas)and relatively large(18nm)mesopores—a typical mesoporous metal oxide has only3–4nm pores.TEM analysis of tetramodal a-MnO2.Transmission electron microscopic(TEM)data for tetramodal a-MnO2,Fig.2, demonstrates a three-dimensional pore structure with a sym-metry consistent with space group Ia3d.From the TEM data,an a0lattice parameter of23.0nm for the mesostructure could be extracted,which is in good agreement with the value obtained from the low-angle powder X-ray diffraction(PXRD)data, a0¼23.4nm(Supplementary Fig.S1a).High-resolution TEM images in Fig.2c–e demonstrate that the walls are crystalline with a typical wall thickness of10nm.The lattice spacings of0.69,0.31 and0.35nm agree well with the values of6.92,3.09and3.46Åfor the[110],[310]and[220]planes of a-MnO2(International Centre for Diffraction Data(ICDD)number00-044-0141), respectively.The wide-angle PXRD data matches well with the PXRD data of bulk cryptomelane a-MnO2(Supplementary Fig. S1b),confirming the crystalline walls.The various pores in tetramodal a-MnO2can be observed by TEM directly:the0.48-nm micropores are seen in Fig.2e(2Â2 tunnels with dimensions of0.48Â0.48nm in the white box);the 4.0-nm pores are shown in Fig.2b–d;the18-nm pores are shown in Fig.2a;the70-nm pores are evident in Fig.2b(highlighted with white circles).Li intercalation.Li can be intercalated into bulk a-MnO2 (ref.46).Therefore,it is interesting to compare Li intercalation into bulk a-MnO2(micropores only)and bimodal a-MnO2 (micropores along with a single mesopore of diameter3.6nm,see Methods)with tetramodal a-MnO2(micro-,meso-and macropores).Each of the three a-MnO2materials was subjected to Li intercalation by incorporation as the positive electrode in a lithium battery,along with a lithium anode and a non-aqueous electrolyte(see Methods).The results of cycling(repeated intercalation/deintercalation of Li)the cells are shown in Fig.3. Although all exhibit good capacity to cycle Li at low rates of charge/discharge(30mA gÀ1),tetramodal a-MnO2shows sig-nificantly higher capacity(Li storage)at a high rate of 6,000mA gÀ1(corresponding to charge and discharge in3min). The tetramodal a-MnO2can store three times the capacity(Li) compared with bimodal a-MnO2,and18times that of a-MnO2 with only micropores,at the high rate of intercalation/deinter-calation(Fig.3).The superior rate capability of tetramodal a-MnO2over microporous and bimodal forms may be assigned to better Liþtransport in the electrolyte within the hierarchical pore structure of tetramodal a-MnO2.The importance of elec-trolyte transport in porous electrodes has been discussed recently35,47,48and the results presented here reinforce the beneficial effect of a hierarchical pore structure.Catalytic studies.CO oxidation and N2O decomposition were used as reactions to probe the three different forms of a-MnO2as catalysts(Supplementary Fig.S2).As shown in Supplementary Fig.S2a,tetramodal a-MnO2demonstrates better catalytic activity compared with only micropores or bimodal a-MnO2;thetemperature of half CO conversion (T 50)was 124°C for tetra-modal a -MnO 2,whereas microporous and bimodal a -MnO 2exhibited a T 50value of 275°C and 209°C,respectively.In the case of N 2O decomposition,a -MnO 2with only micropores demonstrated no catalytic activity in the range of 200–400°C,in accord with a previous report 49.Tetramodal and bimodal a -MnO 2showed catalytic activity and reached 32%and 20%of N 2O conversion,respectively,at a reaction temperature of 400°C.The differences in catalytic activity are related to the differences in the material.A detailed study focusing on the catalytic activity alonewould be necessary to demonstrate which specific features of the textural differences (pore size distribution,average manganese oxidation state,K þand so on)between the different MnO 2materials are responsible for the differences in behaviour.However,the preliminary results shown here do illustrate that such differences exist.Porous LiMn 2O 4.To demonstrate the wider applicability of the synthesis method,LiMn 2O 4with a hierarchical pore structurewas1801601401201008060402000.00.20.40.60.81.0V (c m 3 g –1)Pore diameter (nm)0.0120.0100.0080.0060.0040.0020.000I n c r e m e n t a l p o r e v o l u m e (c m 3 g –1)Pore width (nm)I n c r e m e n t a l s u r f a c e a r e a (m 2 g –1)I n c r e m e n t a l s u r f a c e a r e a (m 2 g –1)P /P 0Figure 1|N 2sorption analysis of tetramodal a -MnO 2.(a )N 2adsorption–desorption isotherms,(b )DFT pore size distribution and (c )Horvath–Kawazoe pore size distribution from N 2adsorption isotherm for tetramodal a -MnO 2.Figure 2|TEM images of tetramodal a -MnO 2.TEM images along (a )[100]direction,showing 18nm mesopores (scale bar,50nm);(b )4.0and 70nm pores (70nm pores are highlighted by white circles;scale bar,100nm);(c –e )high-resolution (HRTEM)images of tetramodal a -MnO 2showing 4.0and 0.48nm pores (scale bar,10nm).Inset is representation of a -MnO 2structure along the c axis,demonstrating the 2Â2micropores as shown in the HRTEM (white box)in e .Purple,octahedral MnO 6;red,oxygen;violet,potassium.synthesized in a way similar to that of tetramodal a -MnO 2.The main difference is the use of LiNO 3instead of KNO 3(see Methods).In this case,Li þreacts with the silica template col-lapsing/blocking the microporous channels in the KIT-6and resulting in the large mesopores and macropores (17and 50nm)in the LiMn 2O 4obtained.The use of Li þinstead of the larger K þdeters the formation of micropores because Li þis too small.TEM analysis illustrates the hierarchical pore structure of LiMn 2O 4(Supplementary Fig.S3):4.0nm pores are evident in Supplementary Fig.S3b;17nm pores in Supplementary Fig.S3a;and 50nm pores in Supplementary Fig.S3b (highlighted with white circles).The d-spacing of 0.47nm in the high-resolution TEM image (Supplementary Fig.S3c)is in good accordance with the values of 0.4655nm for the [111]planes of LiMn 2O 4(ICDD number 00-038-0789)and with the wide-angle PXRD data (Supplementary Fig.S4).The original DFT pore size distribution analysis from N 2sorption (adsorption branch)gives three pore sizes in the range of 1–100nm centred at 4.0,17and 50nm (Supplementary Fig.S5).A more in-depth presentation of the results for LiMn 2O 4will be given in a future paper;preliminary results presented here illustrate that the basic method can be applied beyond a -MnO 2.DiscussionTurning to the synthesis of the tetramodal a -MnO 2,the details are given in the Methods section.Hard templating using silica templates,such as KIT-6,normally gives rise to materials with unimodal or,at most,bimodal mesopore structures,and in the latter case the smaller mesopores dominate over the larger mesopores 8,32,35.Alkali ions are excellent templates for micropores in transition metal oxides 19,21,but they have been avoided in nanocasting from silica templates because of concerns that they would react with and,hence,destroy thesilica20018016014012010080604020D i s c h a r g e c a p a c i t y (m A h g –1)0Cycle numberx in Li x MnO 2Figure 3|Electrochemical behaviour of different a -MnO 2.Capacity retention for tetramodal a -MnO 2cycled at 30(empty blue circles)and 6,000mA g À1(filled blue circles);bulk a -MnO 2cycled at 30(empty red squares)and 6,000mA g À1(filled red squares);bimodal a -MnO 2cycled at 30(empty black triangle)and 6,000mA g À1(filled blacktriangles).18 nm pores70 nm poresTwo sets of mesoporeschannels connecting both sets of mesoporesEtching of silica Etching of silica Etching of silica template2discontinuously within one set of the KIT-6mesoporesFigure 4|Formation mechanism of meso and macropores in tetramodal a -MnO 2.When both KIT-6mesochannels are occupied by a -MnO 2and then the silica between them etched away,the remaining pore is 4nm (centre portion of figure).When a -MnO 2grows in only one set of mesochannels and then the KIT-6is dissolved away,the remaining metal oxide has 18nm pores (upper portion of figure).The comprehensive destruction of the microchannels in KIT-6by K þleads to a -MnO 2growing in only a proportion of one set of the KIT-6mesochannels,resulting in the formation of B 70nm pores (lower portion of figure).template50.Here,not only have alkali ions been used successfully in precursor solutions without destroying the template mesostructure but they give rise to macropores in the a-MnO2, thus permitting the synthesis of a tetramodal,micro-small,meso-large,meso-macro pore structure.Synthesis begins by impregnating the KIT-6silica template with a precursor solution containing Mn2þand Kþions.On heating,the Kþions template the formation of the micropores in a-MnO2,as the latter forms within the KIT-6template.KIT-6 consists of two interpenetrating mesoporous channels linked by microporous channels51–53.The branches of the two different sets of mesoporous channels in KIT-6are nearest neighbours separated by a silica wall of B4nm53;therefore,when both KIT-6mesochannels are occupied by a-MnO2and the silica between them etched away,the remaining pore is4nm(see centre portion of Fig.4).It has been shown previously,by a number of authors,that by varying the hydrothermal conditions used to prepare the KIT-6,the proportion of the microchannels can be decreased to some extent,thus making it difficult to simultaneouslyfill the neighbouring KIT-6mesoporous channels by the precursor solution of the target mesoporous metal oxide33–35.As a result,the target metal oxide grows in only one set of mesochannels of the KIT-6host but not both.When the KIT-6is dissolved away,the remaining metal oxide has B18nm pores,because the distance between adjacent branches of the same KIT-6mesochannels is greater than between the two different mesochannels in KIT-6.Here we propose that the Kþions have a similar effect on the KIT-6to that of the hydrothermal synthesis,but by a completely different mechanism.Reaction between the Kþions in the precursor solution with the silica during calcination results in the formation of Kþ-silicates,which cause collapse or blocking of the microporous channels in KIT-6,such that the a-MnO2grows in one set of the KIT-6mesochannels,giving rise to18nm pores in a-MnO2when the silica is etched away,see top portion of Fig.4. However,the reaction between Kþand the silica is more severe than the effect of varying the hydrothermal treatment.In the former case,the KIT-6microchannels are so comprehensively destroyed that the proportion of the large(18nm)to smaller (4nm)mesopores is greater than can be achieved by varying hydrothermal conditions.The comprehensive destruction of the microchannels in KIT-6by Kþ,perhaps augmented by some minor degradation of parts of the mesochannels,leads to a-MnO2 growing in only a proportion of one set of the KIT-6 mesochannels,resulting in the formation of B70nm pores in a-MnO2,see lower portion of Fig.4.In summary,the Kþreactivity with the silica goes beyond what can be achieved by varying the conditions of hydrothermal synthesis and is responsible for generating the tetramodal pore size distribution reported here. The mechanism of pore formation in a-MnO2by reaction between Kþand the silica template is supported by several findings.First,by the lower K/Mn molar ratio of thefinal tetramodal a-MnO2product(0.08)compared with the starting materials(0.33)implies that some of the Kþions in the impregnating solution have reacted with the silica.Second, support for collapse/blocking of the microporous channels in KIT-6due to reaction with Kþwas obtained by comparing the texture of KIT-6impregnated with an aqueous solution contain-ing only KNO3and calcined at300and500°C.The micropore volume in KIT-6is the greatest,with no KNO3in the solution;it then decreases continuously as the calcination temperature and calcination time is increased,such that after2and5h at500°C the micropore volume has decreased to zero(Supplementary Fig. S6).Third,we prepared tetramodal a-MnO2using a similar synthetic procedure to that described in the Methods section, except that this time we used a covered tall crucible for the calcination step.Sun et al.54have shown that using a covered,tall crucible when calcining results in porous metal oxides with much larger particle sizes.If the70-nm pores had arisen simply from the gaps between the particles,then the pore size would have changed;in contrast,it remained centred at70nm, Supplementary Fig.S7,consistent with the70-nm pores being intrinsic to the materials and arising from reaction with the Kþas described above.Fourth,if the synthesis of MnO2is carried out using the KIT-6template but in the absence Kþions,then the DFT pore size distribution shown in Supplementary Fig.S8is obtained.The0.48-and70-nm pores are now absent,but the4-and18-nm pores remain.This demonstrates the key role of Kþin the formation of the smallest and largest pores and,hence,in generating the tetramodal pore size distribution.The absence of Kþmeans that there is nothing to template the0.48nm pores and so a-MnO2is not formed;the b-polymorph is obtained instead.The absence of Kþalso means that the microchannels in the KIT-6template remain intact,resulting in no70nm pores and the dominance of the4-nm pores compared with the 18-nm pores.The hierarchical pore structure can be varied systematically by controlling the synthesis conditions,in particular the Kþ/Mn ratio of the precursor solution.A range of Kþ/Mn ratios,1/5,1/3and1/2,gave rise to a series of pore size distributions,in which the pore sizes remained the same but the relative proportions of the different pores varied (Supplementary Table S1).The higher the Kþ/Mn ratio,the greater the proportion of macropores and large mesopores.This is in accord with expectations,as the higher the Kþconcentra-tion in the precursor solution the greater the collapse/blocking of the microporous channels in the KIT-6(as noted above),and hence the greater the proportion of macropores and large mesopores.Indeed,these results offer further support for the mechanism of pore size distribution arising from reaction between Kþand the silica template.In conclusion,tetramodal a-MnO2,thefirst porous solid with a tetramodal pore size distribution,has been synthesized.Its hierarchical pore structure spans the micro,meso and macropore range between0.3and200nm,with pore dimensions centred at 0.48,4.0,18and70nm.Key to the synthesis is the use of Kþions that not only template the formation of micropores but also react with the silica template,therefore,breaking/blocking the micro-porous channels in the silica template far more comprehensively than is possible by varying the hydrothermal synthesis conditions, to the extent that macropores are formed,and without destroying the silica mesostructure by alkali ions,as might have been expected.The resulting hierarchical tetramodal structure demon-strates different behaviours compared with microporous and bimodal a-MnO2as a cathode material for Li-ion batteries,and when used as a catalyst for CO oxidation and N2O decomposi-tion.The method has been extended successfully to the preparation of hierarchical LiMn2O4.MethodsSynthesis.Tetramodal a-MnO2(surface area96m2gÀ1,K0.08MnO2)was pre-pared by two-solvent impregnation55using Kþand mesoporous silica KIT-6as the hard template.KIT-6was prepared according to a previous report (hydrothermal treatment at100°C)51.In a typical synthesis of tetramodal a-MnO2, 7.53g of Mn(NO3)2Á4H2O(98%,Aldrich)and1.01g of KNO3(99%,Aldrich)were dissolved in B10ml of water to form a solution with a molar ratio of Mn/K¼3.0. Next,5g of KIT-6was dispersed in200ml of n-hexane.After stirring at room temperature for3h,5ml of the Mn/K solution was added slowly with stirring.The mixture was stirred overnight,filtered and dried at room temperature until a completely dried powder was obtained.The sample was heated slowly to500°C (1°C minÀ1),calcined at that temperature for5h with a cover in a normal crucible unless is specified54and the resulting material treated three times with a hot aqueous KOH solution(2.0M),to remove the silica template,followed by washing with water and ethanol several times,and then drying at60°C.Bimodal a-MnO2(surface area58m2gÀ1,K0.06MnO2)with micropore and a single mesopore size of3.6nm was prepared by using mesoporous silica SBA-15as a hard template.The SBA-15was prepared according to a previous report56.Bulk a-MnO2(surface area8m2gÀ1,K0MnO2)was prepared by the reaction between325mesh Mn2O3(99.0%,Aldrich)and6.0M H2SO4solution at80°C for 24h,resulting in the disproportionation of Mn2O3into a soluble Mn2þspecies and the desired a-MnO2product46.Treatment of KIT-6with KNO3was carried out as follows:1.01g of KNO3was dissolved in B15ml of water to form a KNO3solution.Five grams of mesoporous KIT-6was dispersed in200ml of n-hexane.After stirring at room temperature for 3h,5ml of KNO3solution was added slowly with stirring.The mixture was stirred overnight,filtered and dried at room temperature until a completely dried powder was obtained.The sample was heated slowly to300or500°C(1°C minÀ1), calcined at that temperature for5h and the resulting material was washed with water and ethanol several times,and then dried at60°C overnight.The synthesis method for hierarchical porous LiMn2O4was similar to that of tetramodal a-MnO2.The main difference was to use1.01g of LiNO3instead of KNO3.After impregnation into KIT-6,calcination and silica etching,porous LiMn2O4was obtained.Characterization.TEM studies were carried out using a JEOL JEM-2011, employing a LaB6filament as the electron source,and an accelerating voltage of 200keV.TEM images were recorded by a Gatan charge-coupled device camera in a digital format.Wide-angle PXRD data were collected on a Stoe STADI/P powder diffractometer operating in transmission mode with Fe K a1source radiation(l¼1.936Å).Low-angle PXRD data were collected using a Rigaku/MSC,D/max-rB with Cu K a1radiation(l¼1.541Å)operating in reflection mode with a scintillation detector.N2adsorption–desorption analysis was carried out using a Micromeritics ASAP2020.The typical sample weight used was100–200mg. The outgas condition was set to300°C under vacuum for2h,and all adsorption–desorption measurements were carried out at liquid nitrogen tem-perature(À196°C).The original DFT method for the slit pore geometry was used to extract the pore size distribution from the adsorption branch usingthe Micromeritics software39–42.A Horvath–Kawazoe method was used to extract the microporosity44.Mn and K contents were determined by chemical analysis using a Philips PU9400X atomic adsorption spectrometer.The average oxidation state of framework manganese in a-MnO2samples was determined by a redoxtitration method57.Electrochemistry.First,the cathode was constructed by mixing the active material (a-MnO2),Kynar2801(a copolymer based on polyvinylidenefluoride),and Super S carbon(MMM)in the weight ratio80:10:10.The mixture was cast onto Al foil (99.5%,thickness0.050mm,Advent Research Materials,Ltd)from acetone using a Doctor-Blade technique.After solvent evaporation at room temperature and heating at80°C under vacuum for8h,the cathode was assembled into cells along with a Li metal anode and electrolyte(Merck LP30,1M LiPF6in1:1v/v ethylene carbonate/dimethyl carbonate).The cells were constructed and handled in anAr-filled MBraun glovebox(O2o0.1p.p.m.,H2O o0.1p.p.m.).Electrochemical measurements were carried out at30°C using a MACCOR Series4200cycler.Catalysis.Catalytic CO oxidation was tested in a plug-flow microreactor(Alta-mira AMI200).Fifty milligrams of catalyst was loaded into a U-shaped quartz tube (4mm i.d.).After the catalyst was pretreated inflowing8%O2(balanced with He) at400°C for1h,the catalyst was then cooled down,the gas stream switched to1% CO(balanced with air)and the reaction temperature ramped using a furnace(at a rate of1°C minÀ1above ambient temperature)to record the light-off curve.The flow rate of the reactant stream was37cm3minÀ1.A portion of the product stream was extracted periodically with an automatic sampling valve and was analysed using a dual column gas 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科技风2022年4月机械化工D01：10.19392/ki.1671-7341.202212029 ZnCl2活化水葱制备的生物炭对MB的吸附特性龚光容陈贞羽黄飞陈欢吴汉福*六盘水师范学院化学与材料工程学院贵州六盘水553004摘要：以水葱为原料，氯化锌为活化剂制备了生物炭，研究了制备的水葱生物炭对水中MB的吸附性能.吸附动力学和吸附等温线结果表明：Freundlich等温吸附模型和伪一级动力学模型更适合描述吸附动力学过程，水葱生物炭对MB 的吸附主要是物理吸附，并且具有易吸附特性，伪一级动力学模型理论吸附量达47.75mg/g o关键词：水葱生物炭;MB；吸附染料在纺织、食品、纸张、化妆品等领域有广泛应用曲。

亚甲基蓝(MB)是染料中的一种有机染料,常用于印染行业,如在棉、睛纶等材料进行染色，它具有剧毒性和致癌性，会对人体健康和生存环境造成危害。

研究表明，人长期暴露于高浓度的亚甲基蓝的环境中会引起贫血症、高铁血红蛋白血症、高血压和癌症等疾病⑵。

因此，对含有染料的废水进行处理十分必要。

生物质炭作为一种低成本富碳生物质,是在缺氧或无氧环境中通过热化学分解的副产品。

生物炭原材料来源广、价格低廉,同时具有较高的比表面积和多孔径的结构等特性，被广泛用于废水处理归⑷。

为了进一步提高生物炭吸附性能，可以通过改性。

目前,生物炭改性主要包括物理、化学活化等方式来改善其多孔结构和比表面积、孔隙率等来提高生物炭的吸附能力。

在化学活化过程中，氢氧化钾、氨气、碳酸钾、磷酸、硫酸、氯化锌等是常用的化学活化剂「河。

本文以水葱为原料，氯化锌为活化剂制备生物质炭材料,并考察其对水体中亚甲基蓝(MB)的吸附特性，以期为水葱生物质炭在染料废水处理中提供一定的参考依据。

1实验1.1仪器与试剂KQ-600DE数控超声波清洗器.GB/T23111电子天平, Sx-4-lO马弗炉,101电热鼓风干燥箱.TC19K高速离心机, HG24-HZS-H振荡仪,U1901紫外分光光度计。