Role of hydrogen on adhesion of NiCr thermal sprayed coatings

Managing the Root Zonein Soilless CultureAuthor: Eyal Ronen Haifa Chemicals Chief AgronomistIn solid growing media, there are five important parameters that should be monitored around the root zone to optimize plant growth and yields. EYAL RONEN offers some guidelines on how to manage these parameters to prevent major crop problems, and explains the importance of measuring fertiliser solution at both the dripper and drainage points.General terminologySoilless culture, commonly referred to as ‘hydroponics’, is a cultivation technique by which plants are grown detached from the soil. Plants are cultivated in containers filled with several possible growing media. If these media are solid, the method is called ‘soilless culture’. If no medium is present and the plant roots are bathed in circulated nutrient solution, the method is called ‘hydroponics. If no medium is present and plant roots get their nutrients by frequent spraying or misting, the method is called‘aeroponics’. The method we are concerned with in this article uses solid growing media.Figure 1. Different soilless cultivation methods.Soilless culture characteristicsThe limited volume of medium and water availability generally causes rapid changes in the status of water and nutrients. Changes in the medium solution, such as electrical conductivity (EC), pH and nutrients level, should be monitored for the efficient use of water and nutrients. Failures in the careful supervision of fertilisation and/or the accuracy of irrigation are likely to result in severe plant damage and reduced yields. Hydroponics, however, offers several major advantages in the management of both plant nutrition and plant protection, if the right tools are applied and careful management is carried out.There are five important parameters that should be monitored by the grower, employing simple devices and methods. However, the common perception of some of these parameters is not always correct and this can result in some major problems.There are two reference points of special importance used to determine the status of the medium. These are the ‘drip-line point’ (fertigation input) and the ‘drainage’ point (output), based on the understanding that the drainage point best reflects the condition in the active root zone. By monitoring these two points, it is possible to see what changes are occurring in the medium after fertigation. Changes in the medium environmentWater functions as a source of some nutrients, and as a delivery vehicle to transport nutrients into the plant via the xylem vascular system. When plants are exposed to low relative humidity, they lose water by transpiration through their stomata. Water also evaporates from the medium. However, transpiration and evaporation can lead to a salt build-up in the medium if proper management practices are ignored. Although some salts are absorbed by the plant, there is a sharp increase in the concentration and a build-up of some undesirable salts.When growing in soil, root volume and soil space are large enough that salt accumulation does not interfere with plant growth as quickly. But in soilless culture there is no space to buffer this saltbuild-up, and immediate action is needed to purge the medium and lower the concentration of these dangerous components by washing them away. To avoid this problem, the common practice is to supply extra water at every irrigation cycle to ensure sufficient drainage - irrigation water should pass through most of the medium volume and leach away high salt concentrations at the drainage point. Theoretically, a 10% increase in water volume during daily irrigation cycles should be sufficient, but practically, an extra 30-50% of water is used.When plants are supplied with mineral fertilisers, although some are consumed and some are lost by leaching, the medium solution electrical conductivity is increasing compared to the drip-line point. The accumulation is mainly of nitrate and chloride.It is important to identify the reason for any EC elevation to avoid taking wrong corrective action. For example, chloride is a micronutrient and is required by plants in very small amounts. However, excess chloride will not be absorbed and will easily accumulate in the medium. Because chloride is highly soluble, it will almost always be present in the solution and affect the EC.Nutrient consumption can be roughly estimated by checking the changes in the nitrate (NO3-) content of the nutrient solution. Compared to the drip-line point, it will go up and down, generally reflecting changes in plant consumption. Another form of nitrogen that can tell us about the status of the growing medium is nitrite (NO2-) concentration. In case of over-irrigation, water accumulation in the medium leads to waterlogging, and to decreased availability of oxygen in the medium. This change uncouples the chemical transformation of ammonium to nitrate causing nitrite to appear and accumulate in the medium. The nitrite anion is toxic to plant roots and will eventually lead to plant death.Another important parameter is the pH of the solution flowing through the medium, which can affect the availability of microelements and phosphate to plants. One of the advantages of soilless culture is the ability to control pH in the medium solution. This is achieved by adding acid to the irrigation water to change the ratio between NH4+ and NO3- , which are the only two forms of nitrogen allowed in this cultivation method. It is a common phenomenon that while passing through the root system, the pH will drop slightly due to root respiration and lack of buffer capacity in the soilless medium.It is possible to check these other parameters in the growing medium as well, but this requires relatively sophisticated lab equipment. It should be stressed that EC and pH should be monitored over time, where the trends are more important than the absolute values which are not always accurate. Although the day-to-day measurements of EC and pH are not the most accurate for predicting changes in the crop, relatively inexpensive meters are adequate for quick field evaluations.Table 1. Most important parameters, and how to manage them.Parameter Factorsaffected Units Recommendedrelationshipbetween valueat drainagepoint and at thedripperAction to be taken if undesirable valuesshow at the drainage pointpH Availability ofphosphorusand ofmicronutrients pH units Lower by oneunit, and at therange of 5.5 –6.0Add more acid to the irrigation waterand/or increase ammonium share out oftotal nitrogen.E.C Salinity andwateravailability Deci-siemens/meter orMillisiemens/cmUp to 20%higher.Rinse the medium with a lot of water (2-3fold of the regular volume), enriched witha small amount of 50 ppm nitrogen, if thedrainage EC is 20% above the optimum.Cl-Irrigationvolume ppm Up to 50 ppmhigher.Same action as the above if value atdrainage is 50 ppm or more higher thanat dripper.NO3-Fertilizationstatus ppm Can be higheror lowerIncrease or decrease fertilizationconcentration according to change.NO2-Irrigationintervals or rate ppm Should not bepresent, andmax of 10 ppm.Rinse the medium if >10 ppm is detected.Increase intervals between irrigations andincrease acid application rate.Table 1 is a compilation of common management guidelines used in soilless cultivation. Crop management is generally achieved by comparing EC and pH values between the drip-line point and drainage point; but is the latter the optimal point to compare?In many cases, the values obtained at the drainage point do not reflect the real situation in the active root zone and may mislead the grower about the status of the growing medium. To obtain a more accurate picture, we need to be sure that the irrigation water is passing through all possible pore spaces in the growing medium.Although irrigation water passes horizontally and vertically through the growing medium, several factors can influence which way it moves. A low density of emitters and a high flow capacity, and a growing medium with large aggregate particles and square ‘packing’, will dictate a more vertical movement of the irrigation water. Conversely, a high density of emitters (two lines) and low flow capacity (0.2 l/h), and a medium with small aggregates and triangular shape, will dictate a more horizontal flow of water, thus ensuring a better flush of the medium and a drainage that will be more representative of the status of the growing medium (see Fig. 2)..Big aggregates Small aggregatesLow emitters density High emitters densityLow flow capacity High flow capacityFigure 2. Water movement through the medium in different conditions.Generally, the water found in the drainage does not characterise the real situation near the active root zone. Most of the water in the drainage is collected beneath the dripper from a narrow, sausage-like basin; where water movement is faster than in its periphery. Undesirable salts like chloride show in this water at a lower concentration than can be found in the active root zone, which has a much lower‘hydraulic conductance’. While drainage chloride may show an acceptable situation, a careful inspection of the medium around the active root zone (which is difficult to perform), may show an undesirable concentration of salts, expressed by a high EC.One of the functions of water supplied to soilless culture, other than fulfilling the need of transporting nutrients in plants, is to maintain a low level of salts in the medium and to prevent a possible build-up of salts. Commonsense tells us material cannot disappear from the system. Therefore, although water evaporates from the system, salts do not; hence they will always remain behind. Every anion and cation not consumed by the plant will accumulate in the medium.If the salt is not outside in the drainage it is inside the medium!Growers should aim to allow for an EC value at the drainage point as high as possible and notjust higher by 20% more of the irrigation water at the drip-line point. Also, as high as possible chloride and not only 50 ppm at the drainage, as compared to the irrigation water at the dripper. If the values are only higher by 20% in E.C and 50 ppm in chloride the grower should be worried, since it means the drainage was not effective enough and in this equation the salt is still hiding in the medium. The drainage is ineffective in removing excessive salts with most left in the medium.Growers should check the status of the growing medium at the active root zone. There are two ways to do this. One can dig into some of the medium, squeeze it by hand over a filter paper, and analyse the solution for the relevant parameters. A better method uses a fixed soil-solution extractorthat can extract the medium solution from any location selected by the grower as being a characteristic point to determine the real environment that the plant roots are surrounded by (see Fig. 3).Figure 3. Soil solution extrector inside a pot.Above all, the grower should bear in mind that both methods described for checking the drainage solution and the medium itself are only an approximation. However, because the grower needs some indication of what is going on in the medium, this method of medium evaluation will suffice as long as the EC is not higher than 20% compared to the drip-line EC, and chloride does not exceeds 50ppm over the drip line point, referring to the drainage analysis over there parameters should be higher as possible in comparison to the drip line point.One must also remember that these guidelines are not crop-specific. A better way is to balance the EC specifically for each crop according to its threshold level, above which plant productivity will decrease (see Table 2). The idea is to always keep the EC below this threshold, and when it does exceed this level to take some corrective action and flush the medium with extra water. It’s always better to make frequent small adjustments to the irrigation and fertiliser regime, than to make extreme changes when it is already too late. As a cautionary note, the action of flushing the medium should only be taken when EC levels exceed the threshold and not as a routine, because it will upset the sensitive balance the plants live in.Table 2. Crop salinity sensitivity, threshold and yield decrease (Maas and Hoffman, 1993).Crop Salinity threshold expressedin ds/m Percentage of yield decrease above the salinity threshold % per every ds/mLettuce 1.313 Pepper 1.514 Cucumber 2.513 Tomato 2.59.9Some growers might consider this procedure as labour intensive and rather than checking the ECat the drainage point, they wash the medium heavily from time to time instead. Although this may work,it is the wrong management practice. The methods described in this article will ensure plants are grownin the right zone, beneath the threshold of reduced dry-matter production (see Fig. 4 and Fig 5).TimeFigure 4. Characteristic EC pattern in non-controlled soilless cultivation, with rinsing once in a while. The grey part of the triangle is over the threshold, where productivity decreases.E.C levelTimeFigure 5. Characteristic EC pattern in a controlled soilless cultivation, with rinsing that maintains optimum level with no production losses.Further investigation of ECWhen checking EC of the medium, it is also important to breakdown this general term into its major components. Checking the EC itself will reflect that the concentration of electrolytes is high. At the working range in soilless cultivation, it is important to know whether this EC is due to nitrate nitrogen or chloride. If the majority is from nitrate, it means that the grower has over-fertilised and fertiliser concentration should be lowered. If the majority is from chloride, it means that the grower is not irrigating with a proper volume of water; water consumption is exceeding supply and since chloride only comes from water, it is accumulating very fast. In this case, the appropriate action is to increase the irrigation volume. In both cases, the high EC can be diminished by extra washing, if needed.To sum up, one needs to understand that soilless cultivation is a flexible growing method that lets the grower have full control over the growing environment, including the active root zone. However, plants and yields will suffer if the grower doesn’t have a good understanding of EC and the specific limitations of the crop, the growing medium, and irrigation water. “About the authorEyal Ronen is the Chief Agronomist in charge of market and product development worldwide for Haifa Chemicals. His role includes field research, attending seminars and providing technical support to Haifa agronomists and companies in the distribution channel throughout the world.Email: eyalr@。

Synthesis of a sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst and applications in the hydrolysis of celluloseAnanda S.Amarasekara ⁎,Onome S.OwerehDepartment of Chemistry,Prairie View A&M University,Prairie View,TX 77446,USAa b s t r a c ta r t i c l e i n f o Article history:Received 27February 2010Received in revised form 17May 2010Accepted 19May 2010Available online 26May 2010Keywords:Ionic liquid Acid catalyst Modi fied silica Cellulose HydrolysisA sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst was prepared in 68%overall yield from 3-chloropropyl silica by a simple two step method involving nucleophilic substitution of chlorine with imidazole,then condensation with 1,3-propanesultone and acidi fication using HCl.This silica supported acid catalyst was shown to be effective in the hydrolysis of cellulose (DP ∼450)dissolved in 1-n -butyl-3-methylimidazolium chloride at 70°C,producing glucose and total reducing sugars in 26and 67%yields respectively.Published by Elsevier B.V.1.IntroductionFunctionalized ionic liquids are a signi ficant evolution in the ionic liquid arena and these materials have been developed for various special applications like catalysts,fossil fuel desulfurization reagents,lubricants and as monomers for the synthesis of ionic polymers [1–4].The sulfonic acid group functionalized acidic ionic liquids are an important sub-group in the ionic liquid based catalysts class,and have been used in numerous types of reactions including,esteri fication [5,6],alkylation [7],nitration of aromatic compounds [8],Beckmann rearrangement [9],and alkene polymerizations [10].These acidic ionic liquids can be used in neat or in a solvent in the catalysis applications and requires the separation of the catalyst during the isolation of the product.Immobilization of the functionalized ionic liquids have the bene fits of combining the ionic liquid characteristics with the common advantages of immobilizations,such as ease of recycling and improved selectivity in applications involving catalytic activity.There are several reports on the preparation of ionic liquid covalently grafted silicas as chiral catalysts [11],esteri fication catalysts [12,13],and functionalized hydroxyapatite-encapsulated-Fe 2O 3magnetic nanoparticles [14].Yokoyama et al.has recently reported [15]the immobilization of a sulfonic acid functiona-lized ionic liquid catalyst and application of this catalyst for the esteri fication and nitration of aromatic compounds.In this study,vinyl substituted imidazolium ionic liquid has been grafted on to 3-mercaptopropyltrimethoxysilane modi fied silica gel by free radical polymerization using azodiisobutyronitrile (AIBN)as the initiator.Among various interesting properties of ionic liquids,their ability to dissolve cellulose and lignocellulosic biomass has attracted the attention of a number of researchers in recent times [16,17].In this regard imidazolium ion based 1-n -butyl-3-methylimidazolium chlo-ride (BMIMCl)and 1-allyl-3-methylimidazolium chloride (AMIMCl)are well known for their cellulose dissolution capabilities.However,hydrolysis and degradation of cellulose in the ionic liquid medium is a relatively less explored application for these systems.Zhao et al.has recently reported [18,19]the homogeneous phase hydrolysis of cellulose using concentrated sulfuric acid as the catalyst in 1-n -butyl-3-methylimidazolium chloride medium without any pre-treatment.Furthermore,solid acid catalysts like HY-Zeolite are also known to be effective in the hydrolysis of cellulose in BMIMCl medium [20].Recently,we have shown [21]that cellulose dissolved in Brönsted acidic ionic liquids 1-(1-propylsulfonic)-3-methylimidazo-lium chloride and 1-(1-butylsulfonic)-3-methylimidazolium chloride can be hydrolyzed at 70°C under atmospheric pressure by the addition of 2.0equivalents of water per glucose unit to give glucose along with other reducing sugars.In these experiments,the hydrolysis of Sigmacell cellulose (DP ∼450)in 1-(1-propylsulfonic)-3-methyli-midazolium chloride produced the highest total reducing sugar (62%)and glucose (14%)yields,and was attained with 1h of preheating at 70°C and 30min heating at 70°C,after adding water.Our interest in the use of ionic liquid medium for the acid catalyzed hydrolysis of cellulose into glucose and fermentable sugars for the production of cellulosic-ethanol has led us to study the immobilizationCatalysis Communications 11(2010)1072–1075⁎Corresponding author.Tel.:+19362613107;fax:+19362613117.E-mail address:asamarasekara@ (A.S.Amarasekara).1566-7367/$–see front matter.Published by Elsevier B.V.doi:10.1016/j.catcom.2010.05.012Contents lists available at ScienceDirectCatalysis Communicationsj o u r n a l h o m e p a g e :w ww.e l s ev i e r.c o m /l o c a t e /c a tc o mof sulfonic acid functionalized ionic liquids on silica surface.In this communication we report an ef ficient and simple two step preparation of imidazolium based acidic ionic liquid modi fied silica using 3-chloropropyl silica as shown in Fig.1,and application of this catalyst for the hydrolysis of cellulose in BMIMCl medium.2.Experimental2.1.Materials and instrumentationFluka 60738silica gel 60,220–440mesh (particle size 0.035–0.070mm)was used for the preparation of 3-chloropropyl silica (1).(3-Chloropropyl)triethoxysilane,imidazole,1,3-propanesultone,1-n -butyl-3-methylimidazolium chloride (BMIMCl),and Sigmacell®cel-lulose (DP ∼450)were purchased from Aldrich Chemical Co.FT-IR spectra were recorded on a JASCO-470PLUS IR spectrometer using KBr pellets.Thermogravimetric analysis was carried out in air using TA instruments TGA 2050system.Elemental analysis was performed at QTI laboratories,New Jersey.Total reducing sugars (TRS)and glucose concentrations in aqueous solutions were determined using a Carey 50UV –Vis spectrophotometer and 1cm quartz cells.2.2.Synthesis of 3-chloropropyl silica (1)3-Chloropropyl silica (1)was prepared by using a modi fication of the method used by Adam et al.[22].A mixture silica (10.0g)and (3-chloropropyl)triethoxysilane (10.0mL,9.42g,42.5mmol)in 15mL of toluene was prepared and magnetically stirred for 15min at room temperature,and then re fluxed for 24h.The reaction mixture was cooled,and the product was filtered and repeatedly washed with toluene (3×10mL)and dried under reduced pressure at 100°C for 8h to produce 3-chloropropyl silica 1(10.9g).IR 465,699,802,1096,1638,2963,3453cm −1TGA:stable up to 270°C,5.5%weight loss with the decomposition of all organic structure at 660°C.Chloropropyl group loading was calculated as 0.71mmol/g by using thermogravimetric analysis data.2.3.Synthesis of 3-(1-imidazole)propyl silica (2)To a solution of imidazole (0.774g,11.38mmol)in 25mL of dry benzene,50%sodium hydride in mineral oil (0.546g,11.38mmol)was added and stirred under a nitrogen atmosphere at room temperature for 30min to give sodium imidazole.Then 3-chloropropyl silica (1)(5.00g,3.55mmol of Cl)was added and the mixture was re fluxed under a nitrogen atmosphere for 24h.The resulting product was filtered and washed with ethanol (3×20mL)and dried under vacuum at 100°C for 24h to give 4.93g of 3-(1-imidazole)propyl silica (2).IR 475,797,1093,1513,1638,2962,3453cm −1TGA:stable up to 224°C,7.5%weight loss with the decomposition of all organic structure at 550°C.3-(1-Imidazole)propyl group loading was calculated as 0.69mmol/g by using thermogravimetric analysis data.2.4.Synthesis of sulfonic acid functionalized acidic ionic liquid modi fied silica (3)3-(1-Imidazole)propyl silica (2)(3.78g, 2.61mmol of imidazole group)was suspended in 5mL of dry toluene and 1,3-propanesultone (0.320g,2.62mmol)was added.The resulting mixture was stirred at 100°C in an oil bath for 6h,and then cooled to room temperature,filtered and washed with dry toluene (3×10mL)to give imidazolium salt grafted silica.The intermediate was then treated with 36%w/w concentrated hydrochloric acid (0.266g,2.62mmol)and allowed to stand at room temperature for 24h.The resulting product was washed with ether (3×20mL),dried under vacuum at 100°C for 24h to give 3.96g of sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3)IR 463,803,1102,1565,1640,2932,3447cm −1Found:C,6.82;H,1.49;N,1.70%.Calc.for SiO 2·0.0486(C 9H 16N 2-SO 2Cl)·0.1H 2O:C,7.01;H,1.32;N,1.82%.TGA:stable up to 220°C,17.8%weight loss with the decomposi-tion of all organic structure at 660°C.Sulfonic acid group loading was calculated as 0.67mmol/g by using thermogravimetric analysis data.Determination of acidic sites:Titration of acidic ionic liquid modi fied silica catalyst (3)with 5.05×10−2M aq.NaOH,using phenolphthalein as the indicator gave SO 3H group loading as 0.677mmol/g.2.5.Synthesis of sulfonated silica (4)Sulfonated silica (4)was prepared by reacting silica with neat chlorosulfonic acid at room temperature,as shown in Fig.2,following the literature procedure [23].The acidic site loading in this sulfonated silica (4)was determined as 2.52mmol/g by titration with 5.05×10−2M aq.NaOH,using phenolphthalein as the indicator.2.6.General experimental procedure for hydrolysis of cellulose using 3,4,or H 2SO 4as catalystCellulose (0.030g,0.185mmol of glucose unit of cellulose)was dissolved in 0.300g of 1-n -butyl-3-methylimidazolium chloride (BMIMCl)ionic liquid by heating at 80°C for 4h.Then catalyst (5–10mol%),and deionized water (6.7μL,2.0equivalents/glucose unit of cellulose)were added and the sample was warmed in a thermostated water bath for a pre-determined time for the hydrolysis of cellulose.Then the reaction was quenched by adding 10.0mL of deionized water and transferred to a centrifuge tube and centrifuged at 3500rpm for 6min to precipitate and recover the acidic ionic liquid modi fied silica catalyst.The clear supernatant was collected and the acidic ionic liquid modi fied silica catalyst was repeatedly washed (dispersion in 3mL of deionized water followed by centrifugation,three cycles)for recycling experiments.The supernatant and the washings were combined and the total reducing sugar (TRS)and glucose produced during the hydrolysis of cellulose were measured using the procedures described in the Sections 2.6and 2.7.The average TRS and glucose yields produced in duplicate experiments are shown in Table 1as entries 1–8.Fig.1.Synthesis of sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3).1073A.S.Amarasekara,O.S.Owereh /Catalysis Communications 11(2010)1072–10752.7.Total reducing sugar (TRS)assay for cellulose hydrolyzate 2.50mL of the clear solution from the centrifuge tube was transferred to a vial and 0.50mL of DNS reagent [24]was added.The resulting solution was heated at 90°C for 5.0min to develop the red-orange color.Then the absorbance was measured at 550nm using 1cm quartz cells and Carey 50UV –Vis spectrophotometer.TRS Concentration in the solution was calculated by employing a standard curve prepared using glucose.2.8.Glucose assay for cellulose hydrolyzate1.0mL of the clear solution from the centrifuge tube was transferred to a vial,and2.0mL of glucose assay reagent [25](Sigma-Aldrich Glu 20kit)was added.The resulting solution was heated at 37°C for 30min,and reaction was quenched by adding 2.0mL of 12N H 2SO 4to give a pink solution.Then the absorbance was measured at 540nm using 1cm quartz cells and Carey 50UV –Vis spectrophotometer.Glucose concentration in the solution was calculated by employing a standard curve prepared using glucose.2.9.Reuse of the sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3)The washed acidic ionic liquid modi fied silica catalyst (3)was collected and dried in an oven at 105°C for 24h.This recycled catalyst was used for the hydrolysis of cellulose using procedure 2.5and the hydrolyzate was analyzed using procedures 2.6and 2.7.The results of reusing the same catalyst sample in five cycles are shown in Table 2.3.Results and discussion3.1.Synthesis of sulfonic acid functionalized acidic ionic liquid modi fied silica (3)Sulfonic acid functionalized acidic ionic liquid modi fied silica (3)was synthesized in two steps,and 68%overall yield as shown in Fig.1.3-Chloropropylsilica (1)was first prepared by reaction of (3-chlor-opropyl)triethoxysilane with silica and then nucleophilic substitution of the chlorine with imidazole group gave 3-(1-imidazole)propyl silica (2).Condensation of 3-(1-imidazole)propyl silica (2)with 1,3-propanesul-tone produced the imidazole salt,which was treated with one equivalent of hydrochloric acid to give the sulfonic acid functionalized acidic ionic liquid modi fied silica (3).This is a simple two step linear synthesis of acidic ionic liquid grafted silica when compared with the earlier approach for the preparation of a similar catalyst [15].3.2.Structural characterization of sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3)3.2.1.Elemental analysis and TG –DTGAcidic ionic liquid modi fied silica (3)was characterized using elemental analysis,thermogravimetric –derivative thermogravimetric (TG –DTG)analysis,and FT-IR spectroscopy.The thermogravimetric analysis (TG)curve showed (Fig.3)an initial weight loss of 2.4%up to 110°C due to surface silanol groups and the adsorbed water in plete loss of all the covalently attached organic structure is seen in the 220–660°C temperature range leaving SiO 2,and the organic fraction corresponds to 17.8%weight of the acidic ionic liquid modi fied silica.This decomposition of the organic structure occurs in two steps and the two peaks in the DTG curve at 390and 532°C,are related to 13.0and 4.8%weight losses.The immobilized acid catalyst is apparently stable up to about 220°C.By using the thermogravimetric data,the empirical formula of the catalyst can be calculated as SiO 2·0.0486(C 9H 16N 2SO 3Cl)·0.1H 2O.Structural characterization for the catalyst 3was supported by elemental analysis data shown in Section 2.4.These CHN analysis results are within ±0.19%of the CHN percentages calculated using thermogravimetric analysis based formula:SiO 2·0.0486(C 9H 16N 2SO 3Cl)·0.1H 2O.3.2.2.FT-IRThe FT-IR spectrum of the functionalized acidic ionic liquid modi fied silica (3)is shown in Fig.4.The peak at 1565cm −1canbeFig.2.Synthesis of sulfonated silica (4).Table 1Average percent yields of TRS and glucose produced in duplicate experiments of hydrolysis of untreated cellulose using sulfonic acid functionalized acidic ionic liquid modi fied silica (3),H 2SO 4,sulfonated silica (4),and 1-(1-propylsulfonic)-3-methyli-midazolium chloride (PSMIMCl).EntryCatalyst (mol%)Temperature (°C)Time (h)Yield (%)Ref.TRS Glucose 13(5)a 70 2.02610This work 23(5)a 70 4.02810This work 33(10)a 70 4.05215This work 43(10)a 70 6.06726This work 53(10)a 7010.05519This work 63(10)a90 6.02912This work 7H 2SO 4(10)a 70 6.0386This work 84(10)a70 6.02411This work 9PSMIMCl b 700.56214[21]10PSMIMCl b 70 1.0427[21]11PSMIMCl b704.0294[21]a0.030g of cellulose (DP ∼450)dissolved in 0.300g of 1-n -butyl-3-methylimidazolium chloride (BMIMCl),and 6.7μL of H 2O were added before the hydrolysis.b0.030g of cellulose (DP ∼450)dissolved in 0.300g of 1-(1-propylsulfonic)-3-methyli-midazolium chloride (PSMIMCl),and 6.7μL of H 2O were added before the hydrolysis.Table 2Average percent yields of TRS and glucose produced in duplicate experiments reutilizing catalyst (3)for the hydrolysis of untreated cellulose (DP ∼450).RunYield (%)TRS Glucose 16726265263642446025560220.030g of cellulose (DP ∼450)dissolved in 0.300g of 1-n -butyl-3-methylimidazolium chloride (BMIMCl),and 10mol%catalyst were used in all experiments.Reaction time:6h.Temperature:70°C and 6.7μL of H 2O was added before thehydrolysis.Fig.3.TG –DTG of sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3).1074 A.S.Amarasekara,O.S.Owereh /Catalysis Communications 11(2010)1072–1075assigned to the imidazolium ring,and Yokoyama has reported [15]a similar absorption at 1563cm −1for an imidazolium system attached to a silica surface through alkyl sul fide tether in their preparation of ionic liquid modi fied silica.The Si –O absorption of silica can be observed as a strong peak at 1102cm −1,whereas the weak absorption at 2932cm −1can be assigned to the C –H bonds in 3.Furthermore,the broad absorption in the region of 3447cm −1is due to the Si –OH groups on the surface of the silica.parison of the catalytic activity of acidic ionic liquid modi fied silica catalyst 3with other catalystsHydrolysis of cellulose using acidic ionic liquid modi fied silica catalyst produced glucose and other reducing sugars.The TRS and glucose yields produced in these hydrolysis experiments are shown in Table 1.Initial experiments using 5mol%of the catalyst 3(entries 1and 2)gave relatively low TRS and glucose yields,therefore the catalyst loading was increased to 10mol%in the subsequent set of experiments.The highest TRS and glucose yields of 67and 27%respectively were obtained in the experiment using 10mol%of catalyst 3,at 70°C after a 6h reaction time (entry 4).Heating the sample at 70°C for a longer time (entry 5)or at a higher temperature (entry 6)failed to give better yields of TRS and glucose,indicating the importance of reaction time and temperature in the hydrolysis reaction.Furthermore,longer heating times (entry 5)and higher temperatures (entry 6)produced excessive charring of the sample,giving black residues,and thus lowering the TRS and glucose yields.The experiment using 10mol%H 2SO 4catalyst (entry 7)produced 38%TRS yield and low 6%glucose yield.Sulfonated silica (4)produced only 24%TRS and 11%glucose (entry 8),showing the importance of the imidazolium chloride tether.The higher catalytic activity of acidic ionic liquid modi fied silica catalyst (3)may be due to hydrogen bonding interactions of chloride ion with the hydrogens of cellulose OH groups.Entries 9–11shows the results from our previous work on hydrolysis of cellulose using 1-(1-propylsulfonic)-3-methylimidazo-lium chloride (PSMIMCl)as the solvent as well as the catalyst.Even though,good TRS values are obtained in shorter times (entry 9;62%TRS in 0.5h)using PSMIMCl medium,glucose yields are comparatively lower in these experiments.Furthermore,longer reaction times like 4h (entry 11)resulted in much lower TRS and glucose values.3.4.Reuse of the catalyst (3)The reusability of the catalyst (3)was tested by using the same catalyst sample in five catalytic cycles using 10mol%of catalyst in the hydrolysis of cellulose at 70°C for 6h,and the results of these experiments are shown in Table 2.This catalyst recycling experiment shows that sulfonic acid functionalized acidic ionic liquid modi fied silica catalyst (3)can be reused for the hydrolysis of cellulose in BMIMCl medium with a small loss of catalytic activity.4.ConclusionIn summary,we have demonstrated that sulfonic acid 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CHEMICAL INDUSTRY AND ENGINEERING PROGRESS 2017年第36卷第5期·1658·化 工 进展乙酸蒸汽催化重整制氢的研究进展王东旭1，肖显斌2，李文艳1（1华北电力大学能源动力与机械工程学院，北京 102206；2华北电力大学生物质发电成套设备国家工程实验室，北京 102206）摘要：通过生物油蒸汽重整制备氢气可以减少环境污染，降低对化石燃料的依赖，是一种极具潜力的制氢途径。

乙酸是生物油的主要成分之一，常作为模型化合物进行研究。

镍基催化剂是乙酸蒸汽重整过程中常用的催化剂，但容易因积炭失去活性，降低了制氢过程的经济性。

本文首先分析了影响乙酸蒸汽重整制氢过程的各种因素，阐述了在这一过程中镍基催化剂的积炭原理，讨论了优化镍基催化剂的方法，包括优化催化剂的预处理过程、添加助剂和选择合适的载体，最后对乙酸蒸汽重整制氢的热力学分析研究进展进行了总结。

未来应重点研究多种助剂复合使用时对镍基催化剂积炭与活性的影响，分析多种助剂的协同作用机理，得到一种高活性、高抗积炭能力的用于生物油蒸汽重整制氢的镍基催化剂。

关键词：生物油；乙酸；制氢；催化剂；热力学中图分类号：TK6 文献标志码：A 文章编号：1000–6613（2017）05–1658–08 DOI ：10.16085/j.issn.1000-6613.2017.05.014A review of literatures on catalytic steam reforming of acetic acid forhydrogen productionWANG Dongxu 1，XIAO Xianbin 2，LI Wenyan 1（1 School of Energy ，Power and Mechanical Engineering ，North China Electric Power University ，Beijing 102206，China ；2 National Engineering Laboratory for Biomass Power Generation Equipment ，North China Electric PowerUniversity ，Beijing 102206，China ）Abstract ：Hydrogen production via steam reforming of bio-oil ，a potential way to produce hydrogen ， can reduce environmental pollution and dependence on fossil fuels. Acetic acid is one of the main components of bio-oil and is often selected as a model compound. Nickel-based catalyst is widely used in the steam reforming of acetic acid ，but it deactivates fast due to the carbon deposition. In this paper ，the affecting factors for the steam reforming of acetic acid are analyzed. The coking mechanism of nickel-based catalyst in this process is illustrated. Optimization methods for nickel-baed catalyst are discussed ，including optimizing the pretreatment process ，adding promoters ，and choosing appropriate catalyst supports. Research progresses in the thermodynamics analyses for steaming reforming of acetic acid are summarized. Further studies should be focused on the effects of a combination of a variety of promoters on carbon deposition. Catalytic activity and the synergy mechanism should be analyzed to produce a novel nickel-based catalyst with high activity ，high resistance to caborn deposition for hydrogen production via steam reforming of bio-oil. Key words ：bio-oil ；acetic acid ；hydrogen production ；catalyst ；thermodynamics第一作者：王东旭（1994—），男，硕士研究生，从事生物质能利用技术研究。

Life Depends on the Unique Properties of Water
4.4
All living things are dependent on water. Inside your body, your cells are surrounded by a fluid that is mostly water, and your cells themselves are 70 to 95 percent water. The abundance of water is a major reason Earth can support life.
Conversely, when you cool a substance, the molecules slow and the temperature drops. But as water cools, it forms hydrogen bonds. This releases thermal energy in the form of heat, so there is less of a drop in temperature than in metal.

Cohesion and Adhesion
Each hydrogen bond between molecules of liquid water lasts for only a few trillionths of a second. Yet, at any instant most of the molecules are involved in hydrogen bonding with other molecules because new hydrogen bonds form as fast as old ones break.