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Intake of dissolved organic matter from deep seawater inhibits atherosclerosis progression

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Intake of dissolved organic matter from deep seawater inhibits atherosclerosis progressionGeethalakshmi Radhakrishnan a ,Morio Yamamoto a ,Hironori Maeda a ,Aimi Nakagawa a ,Rajesh KatareGopalrao a ,Hironobu Okada a ,Hideaki Nishimori a ,Seiichiro Wariishi a ,Eiji Toda b ,Hiroshi Ogawa c ,Shiro Sasaguri a,*aDepartment of Surgery II,Faculty of Medicine,Kochi University,Japan bSumiko Techno Research,Co.Ltd.,Ehime,Japan cOcean Research Institute,The University of Tokyo,Tokyo,Japana r t i c l e i n f o Article history:Received 9June 2009Available online 18June 2009Keywords:Deep seawaterDissolved organic matter Atherosclerosis Cyclooxygenase-1a b s t r a c tDissolved organic matter (DOM)in seawater can be defined as the fraction of organic matter that passes through a filter of sub micron pore size.In this study,we have examined the effect of DOM of deep sea-water (DSW)from Pacific Ocean on platelet aggregation and atherosclerosis progression.DSW was passed through a series of filters and then through an Octadecyl C18filter;the retained substance in eth-anol was designated as C18extractable DOM (C18-DOM).Our studies showed that C18-DOM treatment inhibited platelet aggregation,P-selectin expression and activity of COX-1significantly.C18-DOM increased the expression of anti-atherogenic molecule namely heme oxygenase-1in endothelial cells and all these data showed that C18-DOM is exhibiting aspirin-like effects.Moreover our in vivo studies showed that C18-DOM feeding slowed remarkably the progression of atherosclerosis.Our study demon-strated a novel biological effect of oceanic DOM,which has several important implications,including a possible therapeutic strategy for atherosclerosis.Ó2009Published by Elsevier Inc.Atherosclerosis is a progressive disease of arteries,characterized by accumulation of lipids and fibrous elements and is responsible for up to 50%of deaths in the modern society [1].In the history of drug discovery,so far terrestrial resources have been targeted which led to the creation of various medicines.Recently,the trend has been switched on to the oceans,which is considered as a potential source for the next generation of drugs.Chemical compounds extracted from marine organisms such as fungi,sponges have been reported to possess anti-cancer,anti-fun-gal effect,etc.[2–5].In this study we have focussed on the dissolved organic matter (DOM)from deep seawater (DSW).DSW was collected from depths beyond 374meters off (mesopelagic zone)the Cape of Muroto,fac-ing the north-east Pacific Ocean,(Latitude 33.5°N and Longitude 134.10°E)using a DSW-drawing system,where intense up welling of DSW occurs due to the movement of ocean currents.Surface seawater was also collected from depth 5m off at the same loca-tion.The purpose of this research is to examine the effect and the mechanism of action of DOM in DSW on the progression of atherosclerosis.Materials and methodsPreparation of dissolved organic matter.We isolated DOM using a solid phase extraction method in which 1500L of original SW was passed through a series of filters of size 50,5,and 0.2l m pore sizes,respectively (Y.S.Filter Japan)and then through an 3M Empore TMOctadecyl (C18)FF disc (90mm)to retain the organic substance.The filtered DOM was dissolved in 25ml of ethanol and was designated as C18-DOM.To prepare desalinated DSW,ori-ginal DSW was passed through 50,5l m filters,and then desali-nated twice by a reverse osmosis membrane module using HR3155PI (Element Configuration:Hollow fiber,single open-ended)in a desalination plant.1%DSW (v/v)was prepared by diluting original DSW with desalinated DSW to a concentration approximately 1%of that of original concentration.1%DSW (v/v)was passed through 3M Empore TMOctadecyl (C18)FF disc (90mm)to remove remnants of organic matter and the filtrate is designated Inorganic deep seawater (Inorg-DSW).Rabbit balloon injury model.Japanese male white rabbits (JMWRs)weighing 3–3.2kg (Japan SLC,Inc.,Shizuoka,Japan)were used in this study.All animal experimental protocols were fol-lowed in accordance with the Guide for the Care and Use of Labo-ratory Animals published by the US National Institutes of Health (NIH Publication No.85-23,revised 1996)and the guidelines of0006-291X/$-see front matter Ó2009Published by Elsevier Inc.doi:10.1016/j.bbrc.2009.06.073*Corresponding author.Fax:+81888802376.E-mail address:sasaguri@kochi-u.ac.jp (S.Sasaguri).Biochemical and Biophysical Research Communications 387(2009)25–30Contents lists available at ScienceDirectBiochemical and Biophysical Research Communicationsjournal homepage:www.elsev i e r.c o m /l o c a t e /y b b rcour university.Anesthesia was achieved by inhalation of1.39% isofluorane with ketamine hydrochloride(20mg/kg)and pento-barbital sodium(50mg/kg)as pre-anesthetic medication.Balloon injury was performed in RCCA as described[13].Following which the rabbits were divided intofive groups.In group a,b,c,and d rab-bits were fed with50ml of either distilled water,surface seawater, Inorg-DSW,1%DSW(v/v)per day,respectively.The C18-DOM group(e)rabbits were fed200l l of C18-DOM dissolved in50ml of distilled water once a week.All the groups were fed a1%high cholesterol diet for4weeks.After4weeks the animals were sacri-ficed,right common carotid artery(RCCA)was harvested,and Van Gieson elastic staining was performed in paraffin sections to eval-uate the neointimal thickness.Platelet aggregation.JMWRs were divided into three groups.In Group a,rabbits were fed with200l l of C18-DOM dissolved in 50ml of distilled water/week.In group b and c rabbits were fed with50ml/day of1%DSW(v/v)and50ml/day of Inorg-DSW, respectively.Platelets were stimulated by10or40l M of ADP and0.2l g/ml of collagen.Platelet aggregations were measured as a change in light transmittance at the start of the experiment, 1-week,2weeks after feeding[14].Cholesterol measurement.JMWRs were divided into three groups.In control group rabbits were fed with50ml/day of dis-tilled water.In1%DSW(v/v)group,rabbits were fed with 50ml/day of1%DSW(v/v).In C18-DOM group,rabbits were fed with200l l of C18-DOM dissolved in50ml of distilled water/ week.Rabbits were fed with1%high cholesterol diet for 3months.Serum samples were collected at the start and end of the experiment.Flow cytometry.To quantify the P-selectin(platelet adhesion molecule)expression,platelets were isolated from human blood by centrifugation method as described in literature[15].Ethanol in C18-DOM was evaporated in an automatic environmental speed vac system(Savant,Instruments,Inc.Farmingdale,NY)then recon-stituted in an equal volume of distilled water containing5%of eth-anol.Platelets(2Â105)in200l L of buffer were pre-incubated either with1mM of aspirin or50,500,5000times dilution of C18-DOM for15min.Then followed by stimulation with20l M of ADP for10min at37°C.The platelets were suspended in FAC staining buffer(1ÂPBS containing0.05%sodium azide and3% BSA)and then reacted with FITC-labeled mouse anti-human CD62P at recommended dilution(BD Pharmingen)for30min in dark.The platelets were then washed,and analyzed byflow cytom-etry(FACScan;Becton–Dickinson,San Jose,CA).Non-specificfluo-rescence was assessed by substitution of the mouse IgG1k Isotype control.Cyclooxygenase-1assay.Inhibitory activity of C18-DOM on COX-1was assayed by the use of colorimetric COX(ovine)Inhibitor Screening Assay Kit(Cayman,No.560131)according to the proto-col recommended by the supplier[16].The assay was performed in triplicate and repeated at three times.One hundred micromolar of aspirin was used as a reference.Ethanol in100l l of C18-DOM was evaporated in an automatic environmental speed vac system(Sa-vant,Instruments,Inc.Farmingdale,NY)then reconstituted in an equal volume of distilled water.C18-DOM was added to the reac-tion mixture with various dilutions of50,500,5000times that of original volume of C18-DOM.Western blotting.Ethanol in C18-DOM was evaporated in auto-matic environmental speed vac system(Savant,Instruments,Inc. Farmingdale,NY)then reconstituted in equal volume of cell culture medium.Human umbilical vein endothelial cells(HUVECs)ob-tained from ATCC,Manassas(VA,USA)(3Â106)were incubated with5or10l l of C18-DOM and with0.3mM of aspirin as control for12h[17].Expression of HO-1was measured by Western blot-ting with anti-HO-1mouse monoclonal Ab(1:2000,Stressgen Biotechnology).NMR spectroscopy.C18-DOM was subjected to1H,13C NMR spectroscopy(Bruker Biospin Avance400,Ehime Techno Research Center).The ethanol in C18-DOM was evaporated to dryness and reconstituted in MeOD,at25°C.The reference for1H NMR was tet-ra methyl silane(4.699ppm,400.13MHz),and for13C NMR tetra methyl silane(100.1MHz)was used.ESI/TOF/mass spectrometry(MS).C18-DOM was subjected to ESI-TOF-MS(Applied Biosystem Q-STAR XL).The eluant used is H2O/ methanol(1/1)+0.1%formic acid(positive),H2O/methanol(1/ 1)+5mM acetic acid ammonium(negative).The references used were reserpine,dimethylacetamide(positive)and taurocholic acid (negative).Preparation of the biosensor chip.Cyclooxygenase-1(Cayman Chemical,MI,USA)was immobilized(yielding approximately 9000relative response[RU])on the surface of a CM5sensor chip by using an amine coupling kit,following the manufacturer’s instructions[18].The sensor chip surface was washed repeatedly with50mM NaOH for1min at aflow rate of60l l/min.BIACORE for C18-DOM.Mixing of all the reagents,injection,and washing were performed manually by the Biacore J.The running buffer was HBS-N buffer(10mM Hepes/0.15M NaCl,pH7.4)at a flow rate of20l l/min.Ethanol in C18-DOM was evaporated,then reconstituted in equal volume of HBS-N buffer andfiltered through 0.2l m Millexfilter.The mixture was injected for3min over the immobilized surface and the reference(non-immobilized)surface. The surface was regenerated with25mM NaOH for1min at aflow rate of60l l/min.The total run time between the samples was about2min.RUs were recorded on each sensor gram15s after the injection.All RU values were corrected by subtraction of the RUs from the reference surfaces.Statistical analysis.Data were expressed as means±SEM.Differ-ences between means were examined by paired Student’s t-test and p<0.05were regarded as being statistically significant. ResultsC18-DOM inhibits the progression of neointimal hyperplasiaIn balloon-injured RCCAs,the ratio of neointima versus media is significantly reduced in C18-DOM treated group(0.08±0.05ver-sus1.86±0.50,C18-DOM fed versus controls,p<0.05)and also in1%DSW(v/v)group(0.32±0.14versus1.86±0.50,1%DSW fed versus controls,p<0.05)(Fig.1A and B).In contrast there is no significant reduction in the ratio of neointima versus media in Inorg-DSW fed group,which suggests that the anti-atherosclerotic effect is derived specifically from the organic components of sea-water.Moreover our results that the surface water does not have anti-atherosclerotic effect,implies that only DOM existing below the surface ocean may have the effects.C18-DOM inhibits platelet aggregationIn C18-DOM fed group showed significant decrease in platelet aggregation value in2weeks compared to pre value when stimu-lated by40l M of ADP(32.7±5.0versus46.4±3.3,2week value versus pre value,p<0.05).Moreover,C18-DOM fed group showed significant decrease in platelet aggregation value in2weeks com-pared to pre value when stimulated by0.2l g/ml of collagen (45.2±3.3versus69.2±3.0,2week value versus pre value, p<0.01)(Fig.2A).1%DSW(v/v)fed group showed significant de-crease in platelet aggregation value(%of change in light transmit-tance)in2weeks compared to pre value when stimulated by 10l M of ADP(27.0±4.3versus38.5±3.0,2week value versus pre value,p<0.05)(Fig.2B).In contrast,Inorg-DSW has no effect on the platelet aggregation(Fig.2C).26G.Radhakrishnan et al./Biochemical and Biophysical Research Communications387(2009)25–30Cholesterol profile in rabbitsAlthough C18-DOM inhibited the development of neointimal thickness,platelet aggregation,total cholesterol levels were not re-duced.After 4weeks,the total cholesterol level increased from 32.67±14.92mg/dl to 424.74±36.24mg/dl in the control group and from 50.76±9.16mg/dl to 445.40±87.28mg/dl in the C18-DOM group.The differences between the two groups at both the starting (p =0.17versus control)and end point (p =0.41versus control)were not significantly different (Table 1).Aspirin like effects of C18-DOMIn addition to our in vivo studies,we analyzed the effect of C18-DOM on the expression of platelet adhesion molecule named P-selectin upon stimulation by 20l M of ADP.C18-DOM markedly attenuated the P-selectin expression (Fig.3A).To investigate the ef-fect of C18-DOM,we performed COX inhibitor screening assay with aspirin as reference and measured the production of PGF 2a .C18-DOM inhibited the activity of COX-1significantly when compared to vehicle group in a dose dependent manner (Fig.3B).OurWesternFig.1.C18-DOM attenuates the neointimal hyperplasia in balloon injured common carotid arteries of JMWRs.(A)The photomicrographs of Von Gieson elastic lamina staining of balloon-injured RCCAs in distilled water (a),surface SW (b),Inorg DSW (c),1%DSW (v/v)(d)and C18-DOM (e)fed groups’.Scale bar,200l m (n =6).(B)The graph represents the ratio of neointima versus media in various groups.Data are presented as an average for each group.Error bars indicate standard error of means ±SEM.Fig.2.(A)C18-DOM significantly inhibited collagen-induced (0.2l g/ml)PA with **p <0.01.(B)1%DSW (v/v)significantly inhibited the ADP-induced (20l M)platelet aggregation with *p <0.05.(C)In contrast,Inorg-DSW had no effect on the platelet aggregation of rabbit.Data are presented as an average of percentage of change in light transmittance (n =6)for each group.Error bars indicate standard error of means ±SEM.Black shaded,striped,and dotted bars represent the pre,1,2weeks platelet aggregation values,respectively.G.Radhakrishnan et al./Biochemical and Biophysical Research Communications 387(2009)25–3027blot analyses showed that C18-DOM induces the expression of HO-1 in human umbilical vein endothelial cells(HUVECs)in a dose depen-dent manner with a feature similar to that of aspirin(Fig.3C).Further,we conducted chemical characterization of C18-DOM using NMR technique.The results obtained were consistent with Hertkorn,et al.(Supplementary data)[19].Moreover our ESI/TOF/ Mass Spectrometry(MS)analysis showed that C18-DOM is com-posed of molecules with molecular weight ranging from220to 1000amu with peak occurring around400amu(data not shown).Binding pattern of C18-DOM to immobilized COX-1on sensor chipCOX-1was immobilized onto the surface of a CM5sensor chip. Significant difference in response unit(RU=9000)was observed in the sensor gram prior to immobilization and post deactivation, reflecting a successful immobilization of COX-1onto the sensor surface.The resonance unit(RU)indicated the bound mass on sen-sor surface with time.The functionalised CM5chip was evaluated for its ability to detect the binding capacity of molecules in C18-DOM with COX-1.C18-DOM binds to the COX-1yielding a maxi-mum strength atflow rates of100l l/min with an effect similar to aspirin(Fig.4).DiscussionDeep seawater(DSW)designates the water,whichflows below 1000m from the surface of the sea[20].Our previous studies in healthy human volunteers showed that desalted DSW intake inhib-ited the platelet aggregation significantly with p<0.01(data not shown).However,the knowledge about the biologically active sub-stances,which is responsible for the above-mentioned effect,is still unclear.Dissolved organic matter(DOM)is the largest reservoir of re-duced carbon in the oceans.The amount of carbon in oceanic DOM($700Â1015g)is similar to that of atmospheric carbon, which has raised interest in the DOM pool in global carbon cycle research[21].The production of DOM includes extra cellular re-lease by phytoplankton,grazer mediated release,excretion re-lease via cell lyses(both viral and bacterial)and solubilization of particles and bacterial transformation and release[22–26].In contrast with surface DOM,much of the DOM in the deep ocean is quite resistant to microbial degradation,photo oxidation and has an average radiocarbon age of several millennia[27,28].Ef-forts to improve methods for isolation and characterization con-tinued as a major research area in the1980s,with an emphasis on NMR methods[29].DOM has various functions and plays important roles in chemical,biological and even physical ocean-ography[30].Recently,activated platelets have not only been implicated in thrombosis but also in inflammatory reactions,immune responses, and in distinct aspects of atherosclerosis.Importantly,an intermit-tent injection of activated platelets has been shown to exacerbate the formation of native atherosclerotic lesions,a process involving platelet surface receptors that facilitate mononuclear cell recruit-ment.By similar mechanisms,platelet adhesion to subendothelial smooth muscle cells has been shown to increase MCP-1secretion by SMCs,as well as their migratory properties,which appears to be particularly relevant in the context of arterial1injury and reste-nosis.Activated platelets exacerbate atherosclerosis in apoEÀ/Àmice in a P-selectin dependent manner[6–12].Aspirin is a cyclooxygenase-1(COX-1)inhibitor,thus inhibiting the prostaglandin release,which is a mediator of inflammation, platelet aggregation,etc.Previous studies showed that high dose of aspirin(12mg/kg/day)significantly inhibited the neointima/ media ratio in balloon-injured iliac artery compared to control group,although it has no effect on cholesterol level of rabbits. But the most important side effect of high dose is aspirin resistance in the treatment of atherosclerosis.These side effects limit admin-istration of aspirin in the treatment of atherosclerosis[31].Fig.3.(A)C18-DOM inhibited the expression of P-selectin significantly with**p<0.01when compared to vehicle group.Data are presented as means±SEM(error bars) (n=3)of the percentage of meanfluorescence intensity compared with ADP stimulated platelets.(a)Vehicle group;(b)aspirin group(1mM);(c),(d)and(e),C18-DOM group treated platelets at50,500,5000times dilutions.Data are expressed as percentages,arbitrary values of100%being attributed to the vehicle group.(B)C18-DOM attenuated the enzyme activity of COX-1with**p<0.05when compared to vehicle group(unpaired t-test).Data are presented as means±SEM(error bars)(n=3)of enzyme activity for each individual experiments.(a)Positive control(b)vehicle(5%ethanol),(c)100l M of aspirin,(d–f)50,500,5000times dilution of C18-DOM.PG,prostaglandin.(C)Western blotting analysis shows the HO-1expression in HUVECs.(a,b)Expression of HO-1by5or10l l of C18-DOM.(c)Expression of HO-1by0.3mM of aspirin.Table1Total and LDL cholesterol levels in three groups both at the start of the experimentand after4weeks.After4weeks,the total cholesterol level increased from32.67±14.92mg/dl to424.74±36.24mg/dl in the control group and from50.76±9.16mg/dl to445.40±87.28mg/dl in the C18-DOM group.The differencesbetween the two groups at both the starting(p=0.17versus control)and end point(p=0.41versus control)were not significantly different.Groups(Gp)T-CHO(mg/dl)LDL-CHO(mg/dl)Pre Post Pre PostControl Gp32.6±14.9424.7±36.215.1±8.693.8±3.61%DSW Gp44.0±13.3945.6±107.522.9±7.9187.0±23.0C18-DOM Gp50.7±9.1445.4±87.228.8±6.976.2±14.728G.Radhakrishnan et al./Biochemical and Biophysical Research Communications387(2009)25–30It has been reported that heme oxygenase-1(HO-1)exerts anti-atherosclerotic effects in different animal models.Hence HO-1is considered to be a novel therapeutic approach to treat atheroscle-rosis [32–34].Previous reports showed that aspirin induces the expression of HO-1in endothelial cells by NO dependent pathway [17].This is the first study showing the anti-atherosclerotic effects of DOM from DSW.DOM attenuated the neointimal hyperplasia in balloon-injured RCCAs,platelet aggregation,P-selectin expression and COX-1activity.Considering the results of NMR analysis,ESI/TOF/MS analysis and that of the animal and other in vitro experi-ments,we could hypothesize that some compound of marine ori-gin possessing active functional groups similar to aspirin might be present in C18-DOM,moreover C18-DOM consists of many dif-ferent molecules further analysis should be done to differentiate the anti-atherosclerotic activity from that of aspirin.AcknowledgmentsWe thank the Deep seawater drawing system,Kochi prefecture,Japan for providing us the original seawater,surface seawater,1%DSW (v/v),and Inorg-DSW.Appendix A.Supplementary dataSupplementary 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Effect-of-dissolved-organic-matter-from-Guangzhou-landfill-leachate-on-sorption-of-phenanthrene-by-M

Effect-of-dissolved-organic-matter-from-Guangzhou-landfill-leachate-on-sorption-of-phenanthrene-by-M

Effect of dissolved organic matter from Guangzhou landfill leachate on sorption of phenanthrene by MontmorillonitePingxiao Wu a ,b ,c ,⇑,Yini Tang a ,b ,Wanmu Wang a ,b ,Nengwu Zhu a ,b ,c ,Ping Li a ,b ,Jinhua Wu a ,b ,Zhi Dang a ,b ,c ,Xiangde Wang a ,baCollege of Environmental Science and Engineering,South China University of Technology,Guangzhou 510006,PR ChinabThe Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters,Ministry of Education,Guangzhou 510006,PR China cThe Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions,PR Chinaa r t i c l e i n f o Article history:Received 29March 2011Accepted 5June 2011Available online 13June 2011Keywords:Desorption KineticsSurface properties Complex Clay liner Modela b s t r a c tTo investigate the effect of dissolved organic matter (DOM)on the adsorption of phenanthrene (PHE)by montmorillonite (MMT),organic clay complex was prepared by associating montmorillonite with DOM extracted from landfill leachate.Both the raw MMT,DOM,and MMT complex (DOM–MMT)were charac-terized by X-ray diffraction (XRD),Fourier transform infrared (FTIR),X-ray photo-emission spectroscopy (XPS),and scanning electron microscope (SEM).Batch adsorption studies were carried out on the adsorp-tion of PHE as a function of contact time,temperature,and adsorbent dose.The sorption of PHE on complex was rapid,and the kinetics could be described well by the Pseudo-first-order model (R 2>0.99),with an equilibrium time of 120min.The adsorption isotherm was in good agreement with the Henry equation and Freundlich equation.Also,thermodynamic studies showed that the adsorption process was exothermic and spontaneous in pared with MMT,the adsorption capacity of DOM–MMT complex for PHE was greatly enhanced.The effects of DOM on PHE sorption by MMT may be attributed to the changes in the surface structure,the specific surface area,the hydrophobic property,and the average pore size of MMT.A series of atomistic simulations were performed to capture the struc-tural and functional qualities observed experimentally.Ó2011Elsevier Inc.All rights reserved.1.IntroductionPolycyclic aromatic hydrocarbons (PAHs)are formed during the incomplete combustion of fossil fuels and other organic matter.They are classified as persistent toxic substances (PTS)by United Nations Environmental Program (UNEP)because of their persis-tence in the environment,tendency to bioaccumulate,and impact on public health [1,2].Therefore,it is essential to investigate the fate and transport of PAHs and explore the possible influential factors.Comparing with biodegradation [3],adsorption of PAHs on min-eral phases and mineral soil is an efficient remediation process that has decisive effects on their transport,bioavailability [4],and fate in natural environments [5,6].Clay minerals have a high specific surface area and carry a charge,enabling them to bind and stabilize PAHs.Moreover,the surface properties and reactivity of clay min-erals may be modified by adsorption and intercalation of small and polymeric organic species [7].Thus,PAHs adsorption process can be greatly affected by dissolved organic matter (DOM),which is largely composed of humic substances such as fulvic acid (FA)and humic acid (HA).A number of functional groups in DOM,such as carboxylic,phenolic,and carbonyl allow them to interact with PAHs through hydrophobic binding and form humic-solute com-plexes in the aqueous phase.Various terms have been used to describe the resultant products of DOM and clay minerals,such as clay–organic complexes [8],clay–humic complexes [9],or mineral–HA complexes [10].Currently,much research interest for the influence of DOM on PAHs adsorption by soils has been directed toward the interactions between PAHs and clay–humic complexes [11–14].Their results suggested that the influence of DOM on phenanthrene sorption could be primarily described as the net effect of the ‘cumulative sorption’and the association of phenanthrene with DOM in solu-tion [15–18].Some studies revealed that humic acid (HA)fraction-ated from DOM promoted sorption of PAHs on clay minerals,while the others indicated that hydrophilic fractions in DOM impeded the distribution of PAHs into soil solids.These recent studies col-lectively suggest that DOM can affect the sorption of PAHs on clay minerals,and the impact will be dependent on the intrinsic nature0021-9797/$-see front matter Ó2011Elsevier Inc.All rights reserved.doi:10.1016/j.jcis.2011.06.019⇑Corresponding author at:College of Environmental Science and Engineering,South China University of Technology,Guangzhou 510006,PR China.Fax:+862039383725.E-mail address:pppxwu@ (P.Wu).of solute,clay,and DOM compositions[15–19].However,surpris-ingly few systematic researches have been carried out to relate interfacial reaction of PAHs on clay and DOM complexes during the sorption process.Besides,in the present study,the experi-mented DOMs in literatures are generally deriving from organic composts,sediments,sewage sludges,and water from waste dis-posal sites[19].Knowledge of the stabilization of DOM from land-fill leachate on clay minerals is inadequate.And it is difficult to decide how DOM from landfill exerts an influence on sorption of PAHs by clay minerals.So,we draw attention to the effect of differ-ent DOM compositions on sorption of PAHs by clay minerals and these interfacial reaction mechanisms,using obtained structural and energetic information at a molecular level by application of molecular modeling methods.An effective model can capture the structural and functional qualities observed experimentally and provide insight into interaction mechanisms of interest[20].The migration of DOM from landfills is of our concern due to their harmful effects at very low concentrations.Today,a signifi-cant environmental problem in Guangzhou is the municipal and industrial landfills,which can release toxic compounds,such as all kinds of organic pollutants,into the ndfill leach-ate contains four main groups of contaminants such as heavy met-als,natural dissolved organic matter(DOM),and xenobiotic organic micropollutants(XOMs).The DOM may act as a carrier of both organic and inorganic pollutants[21,22].Many kinds of adsorbents have been developed for the removal of DOM from leachate.Recently,the usage of natural mineral sor-bents for wastewater treatment is increasing because of their abundance and low price.One type of clay mineral is bentonite, which is primarily composed of montmorillonite(MMT).More-over,several studies have shown that clay liner materials have important geochemical properties,which can increase the attenu-ation of DOM in leachate.Consequently,montmorillonite(MMT) can be used as clay liner materials to provide a reactive as well as passive barrier in landfill containment systems[21].On the other hand,Clay–humic complexes are commonly formed in clay liner cap when the leachate permeates clay liner materials[23].They play very important roles in regulating the transport and retention of PAHs in soils and sediments[24].However,the influence of those natural clay–organic complexes on environmental behavior of PAHs in soils still largely unclear.Thus,understanding the vari-ous factors affecting sorption–desorption processes of natural complexes in landfill and their quantitative mathematical model-ing is essential for rational planning and operation of site remedi-ation schemes.And the aims of this paper are the following:(i)to ascertain the effects of DOM on phenanthrene sorption by clay minerals and to provide evidence for the attenuation of pollutants in leachate by mineral liners:(ii)to compare the difference be-tween DOM–MMT complexes and the raw MMT on sorption behavior to PAHs and to model the sorption processes of natural complexes in landfill.2.Materials and methods2.1.MaterialsHPLC grade methanol and analytical grade phenanthrene (C14H10)were purchased from Aldrich Chemical Co.with a pur-ity>98%.Phenanthrene(PHE)is a three-ring polycyclic aromatic hydrocarbon.The molecular weights,solubility in water at25°C, log K ow of phenanthrene were178.23g/mol,1.10mg/L,and4.57, respectively[25].Raw calcium montmorillonite(MMT)was ob-tained from Nanhai,Guangdong Province;it had a cation exchange capacity(CEC)of0.78meq/g,pH of6.7,and a basal spacing(d001) of1.55nm.The BET surface area,average pore width,and particle size of montmorillonite(MMT)were measured as76.9m2/g, 78.1nm,and15.52l m.And the colloid composition of MMT was 61.1%,and the chemical composition(wt.%)of MMT was SiO2: 65.56%,Al2O3:17.97%,and SiO2/Al2O3:3.65(quality ratio).All chem-icals used in this study,e.g.,NaCl,Na2CO3,CaCl2,HCl,and NaOH, were of analytical reagent grade,purchased from Guangzhou chemical reagent factory.DOM was extracted from the landfill leachate generated from Datianshan landfill site in Guangzhou.The leachate sample was extracted with CH2Cl2.One liter of sample was initially extracted under alkaline condition(pH=12)by adding drops of1/5(by volume)NaOH solution and then in acidic condition(pH=2)by adding some1/5(by volume)H2SO4using a separating funnel. Then,the concentrated liquid was prepared in0.02mol/LKCl to maintain constant ionic strength,and the pH was adjusted to6 by0.5mol/L NaOH.The DOM solution was shaken in the dark at 180rpm and25°C for24h.After shaking,the landfill leachates were centrifuged at4,000rpm for20min.Then,the supernatant was immediatelyfiltered through a0.45-l m membranefilter. All DOM extractions were preserved at4°C in the dark to prevent microbial degradation,photochemical decomposition,and volati-lization.Gas chromatography–mass spectrometer method(GC–MS)was used to measure the concentration of organic pollutants in the landfill leachate.The chemical characterization method of DOM has been previously reported in detail by Yang et al.[22,26].Table 1gave the concentrations of some target alkane compounds in the landfill leachate samples.In this kind of landfill leachate,at least 87kinds of organic pollutants were discovered,which included 17alkanes and olefins,28aromatic hydrocarbons,six acids,four esters,17alcohols and hydroxybenzenes,seven aldehydes and ke-tones,and four amides.Due to the lack of standard references,only the relative contents of DOM with a reliability of80%or above were listed in Table1.And all the compounds were identified by library(WILEY)search.2.2.Preparation of dissolved organic matter and montmorillonite complex(DOM–MMT)To prepare the complex,MMT sample of1.000g was weighed accurately in200ml of beaker,slowly dropped into100ml diluted DOM solution to make suspension at a solid–liquid ratio of1:100 (w/v).The solution pH was adjusted to the required range[27] by titrating with either1.0M NaOH or1.0M HCl.Then,the vessel was stirred constantly in a thermostatted shaker bath(170rpm)for 15h.Thefinal suspension(DOM–MMT)was centrifuged,washed three times by successive agitations with deionized water,dried at45°C,and then pulverized to pass through a200-l m mesh sieve.2.3.Adsorption studiesA known amount of PHE was dissolved in methanol solution (HPLC grade)to prepare1000mg/L stock solution.Background solution contained5mM CaCl2to maintain a constant ionic strength and100mg/L NaN3to minimize bioactivity.The test solu-tions of PHE at various concentrations were made by spiking stock solutions to the background solution.Methanol content in the test solutions was controlled below0.1%by volume to minimize co-solute effect[28].The adsorption behavior of PHE onto all samples was investi-gated through a batch method.A known amount of a given adsor-bent was mixed well with different concentrations of PHE in50-ml iodineflask.All reactors were placed in a thermostatted shaker bath(170rpm).Then,the resulting suspension was separated by centrifugation at4000rpm;1.5mL of the supernatant was loaded into glass tubes and analyzed for PHE concentrations.P.Wu et al./Journal of Colloid and Interface Science361(2011)618–627619The isotherm experiments were carried out in two sequential steps,a sorption step followed by a desorption step.In the desorp-tion step,the sorbed solute on the solid phase was allowed to des-orb to background solution that was initially free of solute.The contents of PHE in the solution were measured,and desorbed PHE was calculated accordingly[29].2.4.Quantification of phenanthreneQuantification of aqueous PHE was performed by high-performance liquid chromatography(HPLC;L-2000,Hitachi) equipped with a UV detector(L-2420);1.5mL of sample was drawn and injected into the HPLC by an autosampler.The separation was done by the analytical reverse-phase Luna C18column with 250Â4.6mm dimension,5-l m particle size,and100Åpore size (Phenomenex Corp.),thermostated at30°C.Eluting reagent com-prised of90%methanol(HPLC grade,>99.9%)and10%milli-Qwater (Millipore Corp.)at aflow rate of1.0mL/min.The detection wave-length was245nm.The losses of PHE by photochemical decomposi-tion,volatilization,and sorption to tubes were found to be negligible.The sorption capacity of phenanthrene on solid phases was cal-culated using the equations below:qe¼V0ðc0Àc eÞsð1Þwhere q e is the amount of PHE sorbed on solid phases at equilib-rium(l g/g),c0,c e(l g/L)are the initial and the equilibrium concen-tration of PHE respectively,V0is the volume of the solution used (mL),and W s is the initial amount of adsorbent(g).3.Results and discussions3.1.Characteristics of the adsorbent3.1.1.Powder X-ray diffraction(XRD)The XRD results of MMT and DOM–MMT complex are shown at Fig.1.The d001reflection for basal spacing was found to shift from 1.55(original clay)to1.58nm.This proved that DOM molecules did not significantly intercalate the Al–Si layers of MMT and was bound primarily on the edges and outer planar surfaces of MMT. This binding was probably by H-bonding and electrostatic interac-tions between the positively charged edges of the clays and the negative charges on DOM[30].In addition,the slight increase of 0.03nm may also be attributed to ion-exchange reaction between MMT and DOM.Because of small ionic hydrated radius[31],some primary hydrolyzed cations of DOM can replace Ca2+of interlayer of MMT easily and then caused the increase in basal spacing.And the decrease in the peak intensity of DOM–MMT complex sug-gested the formation of a much more disordered crystalline struc-ture.Therefore,DOM–MMT complex showed a delaminatedTable1GC–MS analysis result of dissolved organic matter from landfill leachate.Organic pollytant Relative content(%)Reliability(%)Organic pollutant Relative content(%)Reliability(%)Dacane 1.4983Pentanoic acid,2- 1.6582 Tetradecane0.6887methy-,anhydrideHexadecane 1.4595Hexadecanoic0.1387 Octadecane 2.3680Octadecanoic 1.2689 Eicosane 1.9586Naphthalene0.2697 Indene 1.38841,3-bimethylDocosane 2.7893Coprostenol 4.8780 Tetracosane 2.8696Nanphthalene0.3291 Pyrene0.2086,2-bi-Eucalyptene 2.7390methylBenzoylamide,N,N-bi-methyl-3-methyl0.3088Camphor 2.7398 1,2,4-trimethylbenzene0.2891Cedrol 1.4980 Phenol0.5197Cyclohexanol17.1392 Phenol,4-proply 2.9682,3,3,5-trimethyl87 Carboline0.5693Glycol 1.2683 Heptacosane 3.3180Benzenemethanol 3.3181 Naphthalene 1.3692Benzophenone0.37Octadecanoic 2.1190Valeric acid 2.1081 Nonacosane 5.0483Succinic acid2,3-diehyl- 1.6980 Triacontane 4.14911-.alpha.-terpineol 3.3190 Cholest-4-en-3-one0.2899phenol0.5187 2,6,10,14,18,22-tetra-cosahexaene,2,6,10,15,19,23-hexamethyl-3.09981,4-benzenediol,2-(1,1dimethylethyl0.1493Cholestane,3-ethoxy-,(3.beta.,5.alpha) 1.0483Dihydrocholestenol 1.9195 Phenol,4,40-(1-methyl-thylidene)bis- 1.5794ethanol,2-cholro-,phosphate(3:1) 1.2183 Naphthalene,2-vinyl-0.1590Menthone0.6096 Valeric acid,4-phenyl- 1.8086Decalone0.8185 Ethanone,2,2-dimethoxy-1,2-diphenyl0.6191Pentanoic acid0.7187Phenol,4-methyl- 1.95901,2-benzenedicarboxylic acid,dibutyl ester 1.3590620P.Wu et al./Journal of Colloid and Interface Science361(2011)618–627structure,which can be further proved by the change in the FTIR spectra and SEM analysis.Furthermore,from200ppm to 2000ppm,the change of DOM–MMT complex did not obviously occur in peak intensity and basal spacing.This may due to the sta-ble structure of DOM–MMT,which could not vary with the initial concentration of DOM.PHE adsorption occurred only on the exter-nal surface of DOM–MMT complex,as the complex only swelled toa d001spacing of1.59nm.3.1.2.Fourier Transform Infrared(FTIR)The FTIR spectra for MMT,DOM–MMT complex are presented in Fig.2.The following are the major differences the absorption band of MMT at3427cmÀ1,corresponding to the H–O–H hydrogen bonded water,weakened and shifted to the higher wave number 3441cmÀ1.The results suggested that the association of MMT with DOM was a chemical bonding process instead of a physical process. Moreover,the decrease in the peak at1643cmÀ1(OH bending vibration)intensity and width demonstrated an decrease in inter-layer water content due to the replacement of inorganic cations [32]and the association of hydroxyl groups on MMT surface.This observation showed that the binding of hydrophobic DOM fraction to clay minerals could change the mineral surfaces form hydro-philic to hydrophobic[25,33],leading to the preferential sorption of PHE.In addition,the FT-IR spectrum of the DOM–MMT complex showed a new vibration sign at1402cmÀ1,which were attributed to carboxylic acids or aliphatic compounds[32].However,the band (1402cmÀ1)disappears after adsorption of PHE.These shifts indi-cated that phenanthrene molecules interact stronger with the aliphatic DOM–MMT complex through the phenyl rings than the MMT[25].Thus aromatic hydrocarbons,alcohols,and hydroxy-benzenes in DOM are primarily responsible for the enhancement in adsorption of PHE by MMT.3.1.3.X-ray photoelectron spectroscopy(XPS)The XPS spectra of the O1s,Ca2p levels are shown inFig.3(parts a,b).The charge effect was corrected using the internal reference C1s line from adventitious aliphatic carbon(284.6eV). The recorded lines werefitted using the XPSPEAK4.1program after subtraction of the background(Shirley baseline).Table2shows the relative content of C,O,Si,Al,and C deter-mined by XPS.As for Si and Al,which were included in the crystal structure,the variation in atomic concentration was small.The XPS results for DOM–MMT with a higher Si/O atomic ratio of about 0.5144suggested that Si was well dispersed in the complex and, as such,would facilitate the interaction between MMT and PHE [7,34–37].On the other hand,for a synthetic complex of MMT, the surface C/O atomic ratio(0.348)was much larger than the va-lue of raw MMT(0.212),which indicated that silica layers with three-dimensionally polymerized SiO4units covered the outer par-ticle surfaces of the complex[7].The O1s photoelectron spectrum(Fig.3a)showed that binding energy was shifted toward lower energy side by0.3eV after adsorption.In the same way,the Si2p and Al2p binding energy varied from101.2eV to100.9eV and from72.86to72.66eV, respectively.This result suggested that adsorption sites existed on the phyllosilicate surface,and the lower binding energy also could be attributed to DOM interaction with both‘‘aluminol’’and ‘‘silanol’’edge sites on MMT[7,38].Moreover,as the electron den-sity decreased with the binding energy[39,40],the changed elec-tron density of O1s on MMT surface after associating with DOM could be attributed to its stronger interaction with O2–and OH–ions within the aluminosilicate layers.The results showed that during the combination process on MMT surface,alcohols and hydroxybenzenes fractions of DOM were preferentially sorbed by MMT,while alkanes and olefins fractions were left in the solution [41].And the Ca2p photoelectron spectrum(Fig.3b)showed two peaks and each can be deconvoluted into two components corre-sponding to(i)non-exchangeable Ca2+ions occupying octahedral sites within the layer structure;and(ii)exchangeable Ca2+ions occupying interlayer sites[7].Both the Ca2p binding energyP.Wu et al./Journal of Colloid and Interface Science361(2011)618–627621622P.Wu et al./Journal of Colloid and Interface Science361(2011)618–627tion,which suggests that plural adsorption sites exist on the sur-face and interlayer of MMT.The XPS results are in agreementwith the XRD and FTIR study.3.1.4.Scanning electron microscope(SEM)Fig.4shows the morphology of MMT and DOM–MMT(aÂ5000,bÂ5000)).The image of MMT shows aggregated mor-phology,and a compact structure with non-porous surface.Afterassociation with DOM,the clay surface was changed to a non-aggregated morphology and coarse porous surface.And there werea large number of massiveflakes with severely crumpled struc-tures.The morphological changes may be due to the change inthe surface charge of the particles and the ligand exchange be-tween DOM and hydroxyl groups on MMT surface.Particle sizesof MMT and DOM–MMT complex are shown in Fig.5.As seen,compared with that of raw MMT(15.52l m),the average particlesize of DOM–MMT complex decreased from15.52l m to14.69l m,with increase of the BET area from76.9to101.4m2/gof MMT.The pore size of DOM–MMT complex increased from78.1to102.9nm.The incorporation of DOM could form larger sur-face area and numerous cavities,which resulted in an increase inthe absorption capacity of PHE on DOM–MMT.Fig.4.SEM image of MMT(a)and DOM–MMT(b)(magnification20kVÂ5000).absorbent structure [43].In order to further investigate the effect of temperature on the adsorption,thermodynamic parameters such as change in Gibbs free energy D G were estimated using the following equations:D G ¼ÀRT lnq e c eð2Þwhere D G is the molar free energy change (kJ/mol),R is the gas con-stant (8.314J/mol k),and T is the absolute temperature(K).The mo-lar free energy values of phenanthrene adsorption on MMT and DOM–MMT are summarized in Table 3.The negative values for the D G showed that the adsorption process for DOM–MMT complex was feasible and spontaneous thermodynamically.Moreover,the increase in D G values of DOM–MMT complex showed that the PHE adsorption was favorable on organic clays [25].3.3.Effect of adsorbent doseInitial adsorbent amount was adjusted in the ranges of 0.1–1.0g for adsorption under natural pH at 25°C as shown in Fig.8.Sorp-tion of PHE on per unit mass of DOM–MMT decreased from 193.35l g/g to 21.37l g/g,with increase in the amounts of adsor-bent from 0.1to 1.0g.The observation can be explained that a large adsorbent amount DOM–MMT complex reduced the unsatu-ration of the adsorption sites.Correspondingly,the number of such sites per unit mass came down.In addition,a higher adsorbent amount created particle aggregation,resulting in a decrease in to-tal surface area [44,45].3.4.Effect of pHThe effect of the pH value of the original solution on the adsorp-tion capacity of PHE is shown in Fig.9.It can be seen that the effect of the pH on the adsorption capacity of PHE was weak.Since the log K ow is often used as a descriptor to estimate the (liquid)solubil-ity and polarity,it is a predominant parameter in the sorption ofpolycyclic aromatic hydrocarbons [46].The log K ow of PHE used in our study is 4.57.In other words,its effect on the concentration of the counter ions on the functional groups of the adsorbent and the degree of ionization of the adsorbate during reaction were lim-ited [47],which suggested that pH was not controlling the adsorp-tion process onto the modified MMT.Furthermore,comparatively high adsorption capacity of PHE on the adsorbent still occurred at pH 7.0due to the fact that chemical interactions between PHE and DOM–MMT taken place.3.5.Desorption studiesThe desorption of PHE from MMT and DOM–MMT complex is presented in Fig.10.As is seen from Fig.10,PHE released from the DOM–MMT was less than 9%of the adsorbed amount.The dataTable 2Change of atomic ratios collected from MMT and DOM–MMT before and after adsorption.SamplesC (%)O (%)Si (%)Al (%)C/O Si/O MMT11.16152.63526.318 6.4710.2120.500DOM–MMT17.19949.31525.366 4.9250.3480.5144DOM–MMT–PHE21.12248.02123.5224.7000.4400.48977.Adsorption of phenanthrene on MMT and DOM–MMT at temperature,45°C.Table 3Thermodynamic parameters for PHE adsorption onto MMT and DOM–MMT.SamplesD G (kJ/mol)298K308K 318K MMTÀ7.11À7.89À8.04DOM–MMT À13.5À14.29À14.43Interface Science 361(2011)618–627623also showed that the desorption percent of MMT was higher than that of DOM–MMT.Moreover,the desorption equilibrium of com-plex was achieved after only30min oscillation,while the equilib-rium of MMT achieved slowly.This indicated that DOM modification not only augmented the PHE adsorption capacity of MMT but also increased the bond strength and the stability of adsorption.The release of PHE from the MMT surfaces may be due to a weak hydrophobic interaction between the free and ad-sorbed PHE on the surfaces.In a case,DOM enhanced the salting out of the non-bound PHE molecules from the adsorbed PHE[48].3.6.Kinetics of adsorption and desorptionIn order to investigate the adsorption and desorption processes of PHE on the adsorbents,Pseudo-first-order and Pseudo-second-order models were used.The linear forms of the two models could be expressed as:logðqe Àq tÞ¼log q eÀk1t2:303ð3Þt q t ¼tqeþ1k2q2eð4Þwhere q t(l g/g)and q e(l g/g)are the amounts of PHE adsorbed at time t(min)and at equilibrium,respectively;k1and k2are the sorp-tion rate constants of the Pseudo-first-order equation and Pseudo-second-order equation,respectively.Table4shows the rate constants(k)and correlation coefficients (R2)of the two kinetic models.Pseudo-first-order model for DOM–MMT showed correlation coefficient(R2)of0.994(Table4), whereas that of second-order kinetic order was0.985.The insuffi-ciency of the pseudo-second-order model tofit the kinetics data could possibly be due to the polarity of PHE influencing the sorp-tion process.Moreover,functional groups existing on the surface of DOM–MMT such as–COOH groups and–OH groups also contrib-uted to the chemisorption of PHE on DOM–MMT in solutions.The coefficient of determination R2for the pseudo-first equation of MMT was observed to be close to1,which was higher than that of DOM–MMT.It demonstrated that the sorption of DOM–MMT was more likely to be described by cumulative adsorption mecha-nism[18],the association of PHE with DOM in solution[49],and the modified surface characteristics of MMT due to DOM binding [50].The pseudo-second-order rate constant(see Table5),k2,and q e were calculated from the slope and intercept of the plots of t/q t versus t.The experimental q e values of DOM–MMT were in agree-ment with the calculated q e values.Hence,this study suggested that the pseudo-second-order kinetic model better represented the desorption kinetics,suggesting that the chemical reaction was significant in the rate controlling step of desorption.It as-sumed that the PHE were strongly held to the MMT and DOM–MMT surfaces by chemisorptive bonds,involving valence forces through sharing or exchange of electrons[37].3.7.Adsorption isothermsEquilibrium relationships between adsorbate and adsorbent are described by adsorption isotherms.Fig.11shows the Henry iso-therms of the adsorption of PHE onto the adsorbent.The Henry [49],Langmuir[51],and Freundlich[24]isotherm models were used to describe the equilibrium data,and their linear forms were presented as:k d¼qeeð5Þqe¼k f c neð6Þc eqe¼1ðbq mÞþ1qmc eð7Þwhere c e(l g/L)and q e(l g/g)are the equilibrium concentration of PHE in the liquid phase and in the solid phase,respectively;k d is the distribution coefficient of solute between soil and water;b and q m are Langmuir coefficients representing the equilibrium con-stant for the adsorbate–adsorbent equilibrium and the monolayerTable4Kinetics parameters for PHE adsorption on MMT and DOM–MMT.Adsorbent Pseudo-first-order model Pseudo-second-order modelq e k1R2q e k2R2MMT17.2300.5370.99717.4940.1320.985 DOM–MMT40.0600.8960.99440.0050.0580.989Table5Kinetics parameters for PHE desorption on MMT and DOM–MMT.Adsorbent Pseudo-first-order model Pseudo-second-order modelq e k1R2q e k2R2MMT 3.4390.8400.932 3.724 1.7800.985 DOM–MMT 3.2400.5700.975 3.352 3.2870.989 624P.Wu et al./Journal of Colloid and Interface Science361(2011)618–627。

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例如：1. Ge, J., Woodward, L. A., Li, Q. X., & Wang, J. (2013). Distribution, sources and risk assessment of polychlorinated biphenyls in soils from the Midway Atoll, North Pacific Ocean. PloS one, 8(8), e71521.2. Wang, Y., Zhang, D., Shen, Z., Feng, C., & Chen, J. (2013). Revealing Sources and Distribution Changes of Dissolved Organic Matter (DOM) in Pore Water of Sediment from the Yangtze Estuary. PloS one, 8(10), e76633.网上对这个杂志的褒贬不一，主要论点是年发布三万多篇，稿费一万多。

最近一两年门槛在提高，审稿速度在减缓，平均审稿周期3个月左右。

三：Environmental Pollution:2013年影响因子: 3.902. 最近今年IF在上涨。

这个期刊据说对文章质量要求很高，EP在环境类期刊的名声也挺好。

这个期刊是月刊，审稿周期大于一个月，但是相比较而言较快。

活性炭吸附法实验报告

活性炭吸附法实验报告

活性炭吸附法实验报告1. 实验目的本实验旨在探究活性炭作为吸附剂在去除染料废水中的应用，通过实验验证活性炭的吸附性能。

2. 实验原理活性炭是一种具有大量微孔和孔隙的多孔性材料，具有较大的比表面积和吸附能力。

活性炭材料的孔隙结构可以吸附和储存多种气体、液体或溶质，并在一定的条件下释放出来。

本实验中，活性炭将吸附溶液中的染料分子，实现对染料的去除。

3. 实验步骤3.1 准备工作•准备所需材料：活性炭样品、染料溶液、试管、试管架、移液管等。

•将试管清洗干净，并晾干备用。

3.2 实验操作1.在试管中加入一定量的染料溶液。

2.取适量的活性炭样品，加入试管中。

3.用试管架将试管固定，并加热至一定温度。

4.观察试管中溶液的颜色变化，并记录下来。

5.将试管从加热源中取出，待其冷却至室温。

6.使用移液管将试管中的溶液转移至离心管中。

7.进行离心操作，分离出溶液中的活性炭样品。

8.观察离心管中的溶液，记录下其颜色变化。

4. 实验结果与分析根据实验步骤所得到的结果，我们可以观察到染料溶液在与活性炭接触后发生了颜色的变化。

这是因为活性炭的表面具有较大的吸附能力，能够有效吸附溶液中的染料分子。

通过离心操作，我们将溶液中的活性炭与染料分离，观察到离心管中的溶液颜色明显变浅，说明活性炭对染料的吸附效果良好。

5. 总结与展望通过本次实验，我们验证了活性炭作为吸附剂在去除染料废水中的有效性。

活性炭具有较大的比表面积和吸附能力，能够吸附溶液中的有害物质，实现净化水质的目的。

然而，本次实验仅是基于简单的染料溶液，后续可以进一步研究和探究活性炭在处理更为复杂的废水中的应用。

参考文献[1] Kim, J., Yun, S., & Park, S. (2015). Adsorption of dissolved organic matter onto activated carbon: Mechanisms and kinetic models. Chemical Engineering Journal, 279, 775-784.[2] Wang, S., & Li, H. (2019). Application of activated carbon in water treatment:A review. Journal of Environmental Sciences, 75, 123-135.。

加压溶气气浮法基本流程和特点

加压溶气气浮法基本流程和特点

加压溶气气浮法基本流程和特点The process of pressure dissolved air flotation is a water treatment method that utilizes the principle of dissolved air flotation to remove suspended solids, colloidal particles, and oil and grease from water. This process involves the introduction of compressed air into a pressurized stream of water to create microbubbles, which attach themselves to the contaminants and float them to the surface for removal. The pressure dissolved air flotation process is commonly used in industrial wastewater treatment plants, as well as in municipal water treatment facilities.加压溶气气浮法是一种利用溶解气气浮原理来除去水中悬浮固体、胶体颗粒和油脂的水处理方法。

这个过程涉及将压缩空气引入到加压的水流中，以产生微气泡，这些气泡会附着在污染物上并使其浮到水面上以便去除。

加压溶气气浮法常常用于工业废水处理厂以及市政水处理设施中。

One of the key components of the pressure dissolved air flotation process is the air compressor, which is responsible for supplying the compressed air needed to generate the microbubbles. The efficiency and reliability of the air compressor are crucial to the overallperformance of the flotation system. In addition, the pressure vessel where the pressurization of the water takes place must be properly designed to withstand the high pressures required for the process to work effectively.加压溶气气浮法的关键组成部分之一是空气压缩机，它负责提供所需的压缩空气来产生微气泡。