INVESTIGATION OF THE INTERACTIONS BETWEEN WATER AND MODIFIED SILICA GEL BY IGC AND TPD

Chinese Jourmal of Reactive Polymers2006, 15(1): 1~12Article: 1004-7646(2006)01-0001-12INVESTIGATION OF THE INTERACTIONSBETWEEN WATER AND MODIFIED SILICA GELBY IGC AND TPD*LIXin LI Zhong** XIA QibinXI HongxiaThe Key Lab of Enhanced Heat Transfer and Energy Conservation, College of ChemicalEngineering and Energy, South China University of Technology, Guangzhou 510640, ChinaAbstract: In this work, the thermodynamic parameters for the adsorption of water vapor onuntreated silica gel and silica gel treated with hygroscopic salts and silane coupling agent weredetermined by Inverse Gas Chromatography (IGC) in the infinite dilution region. The desorptionactivation energies of the water vapor on virgin and modified silica gels were estimated by using theTemperature Programmed Desorption (TPD) technique. The interactions between the water and thevirgin and modified silica gels were discussed. Results showed that the thermodynamic parametersand desorption activation energy of water vapour on the silica gels increase with decreasing pore sizeand increasing the surface hydrophilic properties. The desorption activation energy of virgin andmodified silica gels was found to increase with increasing the thermodynamic parameters. The largerthe adsorption parameters and the desorption activation energy were, the interactions between waterand virgin and modified silica gels were.Key words: Silica gel; Pore size; Surface chemistry; Desorption activation energy; ThermodynamicparametersLibrary Clasification No.: TQ028Literature Mark: A1. INTRODUCTIONSilica gel is an amorphous inorganic polymer composed of siloxane (Si- 0 Si) groups in theinner region and silanol (Si- _OH) groups distributed on the surface 田. Silanol groups can beeasily functionalized by different chemical procedures.One tendency of surface modification of silica gel is the preparation of the high hydrophobicsilica gel which can be used as a Chromatography fller(l, support for the catalysts'31 or forimmobilization of bioactive compounds(enzymes, proteins) 4 and for several other purposes.Belyakoval5l synthesized the most hydrophobic silica gels with trimethylsilyl and long chainalkyl groups, and then found that adsorption of water on modified silica gels decreased.TAKASHI [6] increased the hydrophobic properties with various silylation agents containing中国煤化工The Project Supported by: The National Natural sReceived; 20 May, 2006: FoundationJMYHCNMHGFirst Author: LI Xin(1979-), Male, Bom in Henan Province, PhD Candidate.ate. * Corresponding author E mail: cezhi@scut.edu.cn●2●Chinese Joumal of Reactive PolymersJune 20, 2006fluorocarbon-bond. Furukawa 7enhanced the hydrophobic character of silica ge by aradio-frequency CF4 plasma treatment.The other tendency is the preparation of the highly hydrophilic silica gel which can be used indehumidification processes for its good moisture adsorption capacity 8. It is well known thatbesides the developed surface area, the pore structure and surface chemistry of silica gels alsoplay important roles in adsorption of water vapor. Chung 9increased the adsorbed amount ofwater vapor per unit quantity of silica gel using neutron flux iradiation. Wei-Han [10) increasedthe amount of moisture adsorbed using both argon and oxygen plasma treatment. Aristovimpregnated silica gels with hygroscopic salts such as CaCl2 and LiCl which can adsorb thewater vapor by the solid crystalline and/or salt solution. .All of these methods are good for the improvement of adsorption performance of adsorbentsby improving the pore volume and/or surface chemistry. In order to understand the interactionsbetween the adsorbates and silica gels with different surface chemistry and pore size, inverse gaschromatography (IGC) and temperature programmed desorption (TPD) experiments are widelyused. Kiselev 14 investigated the dependency of the adsorption performances to the pore size ofsilica gels by IGC and found that the adsorption heat increases with decreasing pore size of silicagels, particularly for high alkanes. Voelkel (131 studied the influence of monolayer of titanium andzirconium coupling agents on dispersive and acid- base properties of modified silica gel by IGC.Pokrxzovskiy[14)investigated the different pathways desorption of phenylethanol bound bycarbonization to a silica gel surface by TPD MS (mass spectrometry). Gun'ko"5s studied theorganic carbon content of silica gel carbonised by pyrolysis of alcohols by means of TPD.In the present work, thermodynamic parameters for probes water have been determined usingIGC on different silica gels. And the desorption activation energy of the water on the adsorbentswith different surface chemistry and pore size were determined by temperature programmeddesorption(TPD) experiments. The aim of this investigation was to determine the gas/solidsurface interaction between the water and several adsorbents and observe the effect of samples'surface chemstry and pore size on thermodynamic parameters and desorption activation energy.2. THEORY2.1TPD Mathematic ModelTPD technique is a technique of surface analysis i0. It is usually used to estimate bindingenergy between the adsorbate and the adsorbent, and activation energy of desorption, which canbe used to value the adsorbents and estimate adsorption isotherms 0. The TPD spectrum is aplot of the desorption rate of the adsorbate as a function of the sample temperature 16-20.Assume that the kinetics of the desorption process follow the first order kinetics工__ d日s中国煤化工(1)dtYHCNMHGwhere rd is desorption rate of a component A from unit adsorbent,(mol/min), Ns is the maximumVol. 15 No.1Chinese Journal of Reactive Polymers●3●concentration of the component A on an unit surface of the adsorbent (mol/cm2), Ba is antransient coverage of the component A, and t is time(min). Where ka is defined as follows(2)ka =kgexp(- )where ko is cofficient of desorption rate, Ed is activation energy of desorption (kJ/mol), and R isgas constant. Substituting equation (2) into equation (1), ones getr.__ dθ= koo0sexp( - R7_E(3)N"-- dSuppose the TPD experiment has been designed so the temperature, T (K), varies with time.T=To+βyt .(4)where PH is heating rate, K/min. The time derivative of eqn. (3), can be expressed asdr=k。()exp(- E)+ko0,导六exp(-x") ()N, di=koa)expf- RIRT dAs seen generally in the curve of TPD, when T=Tp(peak temperature), draldt=0. SubstitutingdrJ/dt=0, T=Tp ,(3), (4) into (5) and rearranging the eqn, ones can getRT?(6)βπR(r,)(别)If a series of TPD experiments are conducted at different heating rates, corresponding TPDcurves and values Tp could be obtained. After that, a plot of ln(RTp Iβr) versus 1/Tp will yield aline with slop Ej/R. As a result, from the slop of the line, Ed can be found out, and then ko can bealso obtained from the intercept of the line.2.2 IGC TheoryGas solid chromatography when applied to the investigation of solid surface properties isusually called inverse gas chromatography (IGC). The Inverse Gas Chromatograph may beperformed either under infinite dilution conditions or under finite concentration conditions. It isassumed in the case of infinite dilution chromatography that when very small amounts of solutesare injected, the adsorption can be described by Henry's law. The specific retention volume, Vg,in cm'/g, is the fundamental quantity measured in this method. The retention volume of theprobe molecule is a reflection the bonding strength between the probe molecule and adsorbentsurface. The specific retention volume is calculated using following the formula (21- 0:V,=Fjm中国煤化工(7)出YHCNMHGwhere tR is the retention time in min, t, the dead time, po, the outlet column pressure, Pi, the inlet●4.Chinese Journal of Reactive PolymersJune 20, 2006pressure, Pw the vapor pressure of water at the ambient temperature 2 , Tmeter, the ambienttemperature, and j, the James -Martin compressibility factor which was defined as (1-2430:3,(P1P,)2-(8)2(P,1Po)- 12.2.1 Free energy of AdsorptionWhen molecular probes are injected at infinite dilution, the standard free energy to transfer 1mol of adsorbate from the gas phase to the surface at standard state, defined as the variation inthe standard free energy of adsorption, Gas(J/mol), can be expressed a2-242.2.2-301:PoVg(9)△Gas =-RT In|π,Ao[21-24,26,27, 2931]△Ga =-RTInVg +C(10)where R is the ideal gas constant, T is the column temperature, A is the specific surface area, Pois the spreading pressure of the adsorbed gas in the De Boer standard state, which was taken as338 μN/m (22]. The parameter, C, is a constant that takes into account the weight and specificsurface area of the packing material and the standard states of the probes.2.2.2 Enthalpy of AdsorptionThermodynamic data describing the adsorption process were derived from the temperaturedependence of the specific retention volume. When infinite dilution conditions are fuflleld thestandard differential heat of adsorption is numerically equal to the opposite of the adsorptionenthalpy (OHads) which can be calculated from the Gibbs-Helmholtz equation13.1. .a(Gads )-.=.△H,ad -= -.dInVNdTT2Thus the differential enthalpy of adsorption, NHA , may be determined by measuring valuesfor Vg at dfferent column temperatures. And at low surface coverage, the heat of adsorption canbe obtained from the slope of ploting nVg against 1/T, according to Eq. (5)!(272.30.321.F(In V,)(12)△Hads=-R8(1/T )2.2.3 Entropy of AdsorptionIn infinite concentration region, from the adsorption standard free energies and standardenthalpies, adsorption entropies were calculated from the classical equation(24.26-28, 29.30.32].△G= SH ax-T。中国煤化工(13)41HCNMHG_where Tav is the average temperature. The values are inagrceuncnl WIll uie iicarity in (-OG&'IT)vs (1/T) plots, and the adsorption entropies were independent of temperature.Vol. 15 No. 1Chinese Journal of Reactive Polymers.5.3. EXPERIMENTAL SECTION3.1 Silica Gels and ReagentsThree kinds of the silica gels (A-type, B-type and C-type) used in this study were purchasedfrom Qingdao Haiyang Chemical Co, Ltd & Spegial Silica Gel Factory (Qingdao, China).Theirparticle sizes ranged from 0.45mm to 0.9mm. Prior to use, they were dried at 413K in a vacuumfor 4 hours. And they will be referred in the text as Asi, Bsi and Csi, respectively.Prior to the modification, silica gels were dried at 413K in a vacuum for 4h. A 10g host C-typesilica gel was immersed and kept in the 20ml 1mol/L solutions with different salts for 8h. Thenthe samples were taken out of the solution and laid in a 413K oven for 4h. At last, the dryadsorbents were placed in a vacuum desiccator for use. The adsorbents of C-type silica geltreated by 1mol/L CaCl2 and LiCl will be referred in the text as Ca/Csi and Li/Csi respectively.The desiccant C-type silica gel was firstly put into 15ml pure KH550 (y-aminopropy1ethytrimethoxysi1ane,AR) for 1h, then was fltrated and put in the microwave field of 600Wfor 15min. The sample was dried at 140°C for 2h after rinsing with water acetone, methanol andwater. This modified silica gel will be referred to as KH550/Csi in this paper.3.2 Nitrogen Adsorption ExperimentsThe specific surface area, pore volume, and average pore diameter of samples were measuredby nitrogen adsorption at the liquid nitrogen temperature 77K with the help of Micromeritics gasadsorption analyzer ASAP 2010 machine. The silica gel sample was degassed at 573k for 3h in avacuum before the nitrogen adsorption measurements. The BEeT surface area was calculatedfrom the adsorption isotherms using the standard Brunauer- Emmett-Teller (BET) equation. Thepore size distributions (PSD) were determined using DensityFunctional Theory (DFT) based onstatistical mechanics. The specific surface area and the pore volume of the gels were measuredby the BET method. The average pore diameter Dp =4Vp/SBET(assuming a cylindrical shape ofpores) was calculated from the BET surface area and pore volume.3.3 IGC ExperimentsIGC experiments were conducted using a GC9501 gas chromatograph equipped with aThermal conductivity detector (TCD) in the infinite dilution region. The stainless steel columns(13cm long, 3mm in diameter) were flled with silica gel particles of size ranging from 20meshto 40mesh. The samples were conditioned at 473K in the chromatographic column with highpurity nitrogen at a flow rate of 100ml/min for 12h prior to IGC analysis. The injector anddetector temperature was fixed to 453K. In order to meet the requirement of adsorption atinfinite dilution, corresponding to zero coverage and中国煤化工olume of probe(0.1μl) was injected into the GC column. For eaci:THCNMH Gthree repeatedinjections were taken and each retention time was obtained trom the average OI IGC peaks. Datawere recorded in various column temperatures: 383K, 393K, 403K, 413K, and 423K. The●6.Chinese Jourmal of Reactive PolymersJune 20, 2006retention times of water were determined at several temperatures to determine AH and SS.3.4 TPD ExperimentsThe TPD experiments were conducted respectively at different heating rates from 6K/min~15K/min. In each experiment, the sample that had adsorbed the water vapor was packed in astainless reaction tube whose inner diameter was 0.3cm and whose packed length was 0.5cm.Subsequently the stainless tube was placed in a reaction furnace and then heated in thehigh-purity N2 flow at a constant rate 60m/min. The desorbed water vapor was measured byusing the GC 9501 chromatograph with a thermal conductivity detector (TCD) at the outlet ofthe stainless reaction tube, and effuent curves were recorded, which were called the TPD curves.According to experimental TPD curves, the application of equation (8) can estimate theactivation energy for desorption of water on three kinds of the silica gels with the average porediameters of 2.0nm, 5.28nm and 10.65nm respectively.4. RESULTS AND DISCUSSION4.1 Textural PropertiesThe structure parameters of the silica gels derived from the basis of the nitrogen adsorptiondata were summarized in Table 1.Table 1 Porous Structure Parameters of Silica GelsSilica gelsBET surface area (m2/g)_ Volume of pores (cm/g) Average pore diameter (nm)_A690.50.35602.062Bai591.350.81795.288Cs349.20.955510.65Li/ Cgi242.50.837113.76Ca/Cj212.10.838315.33KH550/ C259.60.65696.125The table clearly indicated that Asi is micropore silica gel but Bsi and Ci are mesopore silicagel. Additionally, surface modification through CaCl2 and LiCl was found to raise the averagepore diameter and decrease the pore volume significantly. This was probably due to themicropore in Ciica gel blocked by the CaCl2 or LiCl impregnated. But the average pore diameterand pore volume of KH550/ Ci both decreased ,this maybe due to the silane coupling reagentgrafting onto the inter surface through chemical bonds.4.2 The Effects of the Pore Sizes and Surfad中国煤化ImodynamieParametersTYHCNMH GThe specific retention volume, S, was calculated using the above equation Eq. (7), and theresults were given in Fig. 1. It was noticed that the specific retention volume decreases withVol. 15 No.1Chinese Journal of Reactive Polymers●7●increasing temperature, which also indicated that the interactions between water and silica gelsdecreased with the increase of temperature.2500-15-2000主- o- Ca/C。-18--- - LiC1500- 0一KH550IC.>“1000- o -LiC。一0- KJH50TC.-24+500380410420390400410 420Temperature (K)Fig. 1 The Specific Retention Volume of SilicaFig. 2 The Standard Free Energies of Adsorption ofGels at Different TemperatureWater on Silica Gels at Different TemperatureThe standard free energy of adsorption, OGads, was calculated from Eq. (9).Values of thestandard free energies of adsorption of water at different temperature were given in Fig. 2. Thedecrease of adsorption free energy with increasing temperature followed the Equ. (9). It can beseen that Li/Csi and Ca/Csi exhibit the largest SGads values; followed by those untreated silicagels and, finally, the KH550/Csi. From the results, It was observed that the standard free energyof adsorption increase with the decreasing the pore size and the increasing the surfacehydrophilic properties (5].-30-0.07OH(KHSO1C.J=-45. 61J/mo-40-0.0877SC2E-48.59k3mok三三的从 B上4931K/m-50-s -0.090H(A)-51.613/kmm-A. . +B.-60-siBiC )-5793k/mol-0.10-HH.(CaIC.j-=63.79kImol2.42.52.6380 39040010/rFig.3 The Dependency of Adsorption EnthalpiesFig. 4 The Adsorption Entropies of Waterto the Temperatureon Silica Gels at Different Temperature中国煤化工Thermodynamic data describing the adsorption pr.MYHC N M H G the temperaturedependence of the specific retention volume. At low surface coverage, Adsorption enthalpies(OHads) was given by Eq.(12) and obtained from the slope of plots of ln Vg versus 1/T (Fig. 3),●8.Chinese Journal of Reactive PolymersJune 20, 2006and results are summarized in Fig. 3. It was observed that the heats of liquefaction for water(40. IkJ/mol) are smaller than the enthalpy of adsorption values given in Figure 3. The differencebetween the heat of liquefaction and the heat of adsorption implies that the enthalpies ofadsorption measured were not only due to the heat of condensation of the compounds onto thesilica gels, but also to physico- chemical interactions such as hydrogen bounds and dipole dipoleinteractions between water and silica gels. Similar results were found by Boutboul et al. (25 forthe starch when the sorption of aroma compounds was studiedFor the untreated silica gels, it was noticed that the enthalpies of adsorption increased with thedecreasing pore size. The Similar results also can be observed in silica gels and other adsorbentssuch as zeolite and aluminophosphates[1232-34]It was also observed that the adsorption enthalpies of water on Li/Csi and Ca/Csi were largerthan those on Ci, but the adsorption enthalpies of water on KH550/Ci were smaller than thoseon Csi. High values of AHads, indicated a strong adsorbate- -adsorbent interaction, and hencesolutes interactions with Li/Csi and Ca/Csi were found to be stronger than those on Csi andKH550/Csi. And the adsorption strength of water on adsorbents decreased according to thefollowing sequence: Ca/Csi>Li/Csj>Csi>KH550/Csj. This tendency was in good agreement withthe standard free energies of adsorption (Fig.2) and desorption activation energy (Table 2). Acomparison of the adsorption enthalpies of silica gel with different surface chemistrydemonstrated that there were obvious differences in interactions between water and differentsilica gels studied. The treatment of silica gels with highly hydrophilic salts (1 can significantlyincrease the adsorption enthalpies, but the treatment with hydrophobic silane coupling agent51decreased the adsorption enthalpies.From the adsorption standard free energies and standard enthalpies, adsorption entropies werecalculated according to Eq. (13). The Values of adsorption entropies were given in Fig. 4. It wasfound that the adsorption entropies were independent of temperature. It also showed that theadsorption was spontaneous process because the entropies were negative value. And the largerthe absolute value of entropies was, the stronger the spontaneous tendency of adsorption was.4.3 The Effects of the Pore Sizes and Surface Chemistry on DesorptionActivation EnergiesTPD spectrums of water desorption from three untreated silica gels and three treated silicagels at different heating rates were shown in Figures 5~10. It can be seen that there was anobvious peak in each TPD spectrums due to desorption of water vapor on the silica gels. Agradual increase in the heating rate βH led to an increase in the peak temperature Tp. The peaktemperatures, Tp, can be obtained from the TPD spectra depicted in table. 2. Knowing the valuesof Tp for different heating rates, it was possible to emplov eauation (8) to estimate the desorptionactivation energy of water from the silica gels studidYH中国煤化工e corespondinglinear dependencies of the resulting plots of 1/Tp vers.CNMHGilicagels.Fromthe slop of these lines, activation energy Ed can be found out, and then ko can be also obtainedVol. 15 No. 1Chinese Joumnal of Reactive Polymers●9●from the intercept of these lines, as shown in Figure 11. The calculation results of the desorptionactivation energy of water on the different silica gels were listed in Table 2. The desorptionactivation energy of water on Asi, Bsi, Csi, Ca/Csi, Li/ Csi and KH550/Csi were 35.54kJ/mol,31.41kJ/mol, 26. 16kJ/mol, 43.1 1kJ/mol, 36.40kJ/mol and 22.97kJ/mol, respectively.86四=356.9KB 8k/minT =359.0ks|B_8k/minT=352.3K|4■T=355.8B._7k/minB_=7k/minm T=350.5kB._6k/minI I T=347.JIR|2■=345.1KB-5k/min■T=341.8KB.=Sk/minB,=4k/minB.=4k/min300350400450100Temprature (K)Fig.5 TPD Spectrum of Water on Ast at DifferentFig. 6 TPD Spectrum of Water on Bsi at DifferentHeating RatesT=3593KT=371.8Ki T:369.0K■T=355.2B.8k/minB._-8k/min, T=349.0KB.=Ix/minB.=71/minT =343.7KB.-/miB._-k/min宫2-B.=5k/minT=337.8KB_4k/minB._4k/min400 .320360440 480Fig. 7 TPD Spectrum of Water on C&i at DifferentFig. 8 TPD Spectrum of Water on Li/ C at DifferentFor three untreated silica gels, it suggested that the desorption activation energy of water onthe silica gels increased as the pore sizes the silica gels decreased. In other words, the smaller thepore size of the silica gel was, the higher the desorption activation energy of water on the silicagel became. This was because attraction forces acting on the water molecule from the surfaceforce field on the surrounding walls became stronger if the pore sizes the silica gels were smaller.As a result, the desorption activation energy of water中国煤化工e to its smallestaverage pore size, while that on Csi silica gel was thefYHCNMHGverageporesizefor the silica gels studied.●10●Chinese Joumnal of Reactive PolymersJune 20, 2006But for the silica gels treated with hydrophilicsalts and silane coupling agent, it was differentfrom three untreated silica gels. It was seen that the, 373.9Kdesorption activation energy of water on the silica; |6gels treated with hygroscopic salts was larger thanB.-8k/mindesorption activation energy of water or.4r T-366.%B_=7kminT 360.8KB._6k/minuntreated Ci due to the strong interactions between gwater and the hygroscopic salts, even larger than12B skminB.-4k/mimthe desorption activation energy of water onuntreated Asi with smaller pore size. And it was320360400440 480also seen that the desorption activation energy ofTemprature (K)the water on CalCsi was much higher than that ofFig. 9 TPD Spectrum of Water on Ca/Csat Different Heating RatesLi/ Csi because the polarizabilities of the Ca2+ (x(Ca2+) =0.471) were higher than those of Li+(a (Li+)= 0.029)59. The desorption activation energy of water on KH550/ Csi was clearly smaller thanhat of untreated Ci because the silica gel modified by silane coupling agent was highlyhydrophobics. The weak interactions between the hydrophobic surface and water was thoughtto be responsible for the smaller desorption activation energy of water on KH550/Cj.r=358.JK，6T:=353K-12.0ui/C."B.=8k/min- o- KH550/C( 7347.7K4B.=7k/min-12.2-! EA.5.54kJ/moEjB-31.41kJ/mo? 7，341KEgJO)-61.6k/mo8|21-12.4EILC )36.40/m0//a 7.=334.0KB._=5k/minEjJIC-)-43.11kJ/mB4k/minEJ(KH5soC )22.97:J/mo-12.6+-440480-3.0 -2.9-2.8-27 -2.6-10/T,Fig. 10 TPD Spectrum of Water on the KH550/ C3iFig. 11 Linear Dependence between In(RTp/Br) and1/Tp for TPD of Water on the Silica Gels5. CONCLUSIONSIGC was successfully applied to readily obtain the thermodynamic parameters (4H, 4S and4G) for the adsorption of water vapor on different adsorbents. The desorption activation energyof water obtained by TPD experiment can reflect the in中国煤化工" and silica gels.In summarizing the resuNts, the following conclusions mTYHCNMH G_1) IGC and TPD have proved to be very useful techniquosur stuauyung uIC licraction of waterwith untreated and treated silica gels. These two techniques give coherent results.Vol. 15 No. 1Chinese Jourmal of Reactive Polymers●11●2) The thermodynamic parameters and desorption activation energy of water on the silica gelsincrease with decreasing pore size and increasing the surface hydrophilic properties.3) the interactions between water and virgin and modified silica gels increase with increasingthe adsorption parameters and the desorption activation energy.Table 2 Desorption Peak Temperatures of Water at Different Heating Ratesand Desorption Activation Energies of Water on the Silica GelsAdsorbentDesorption peak temperature (Tp. K) at different heating rates Desorption activation energy4K/min5K/min6K/min7K/min8K/min(EA, kJ/mol)Asi345.1350.5355.0.359.0362.535.54B。341.8347.1352.3356.9360.731.41C337.8343.7349.0355.2359.326.16 .Ca/Ci360.8366.0370.2373.9376.643.11Li/Cg358.2362.2365.8369.0371.836.40KH550/C334.0341.7347.7353.3358.1 .22.97AcknowledgementThe authors would like to thank the National Natural Science Foundation of China (No.20336020) and the science & technology foundation of the city of Guangzhou for financialsupports.REFERENCES[1] Cestari Antonio R., Vieira Eunice F. S., Nascimento Alisson J. P., de Oliveira FlaviaJ. R. ,Roy E. Bruns, Claudio Airoldi , J. Colloid Interf. Sci. [J], 2001, 241(1): 45~51.[2] Buszewski Boguslaw, Jezierska Marta, Ostrowska-GumkowskaBarbara, Mater Chem. Phys.[], 2001, 72(1): 30~41.3] Kubota Lauro T, Gambero Alessandra, Santos Antonio Santana, Granjeiro Jose M., J.Colloid Interf. Sci. [J], 1996, 183(2): 453~457.[4] Seung Won Park, Yong In Kim, Koo Hun Cbung et al, React. Funct. Polym. [], 2002,51(2-3): 79~92.[5] Belyakova L. A., Varvarin A. M., Colloid Surface A [J], 1999, 154(3): 285.[6] Takashi Monde, Nobuyuki Nakayama, Koji Yano, Toshinobu Yoko, Takeo Konakahara, J.Colloid Interf. Sci, [], 1997, 185(1): 111~118.[7] Furukawa K., ljiri H, Terayama H. et al., J. Mater Sci. Lett. [], 2000, 19(17): 1545~1547.[8] Chang K.-S., Wang H-C., Chung T.-W., Appl. Thrm. Eng. [], 2004, 24(5-6): 735~742.[9] Chung T.-W, Chung C.-C., Chem. Eng. Sci, [], 1998, 53(16): 2967~2972.[10] Tao Wei-Han, Chang Kuei- Sen, Chung Tsair-Wang Chang中国煤化工. Eng. Commun.[], 2004, 191(5): 682~693.[11] Aristov Yu. L, Restucia G, Cacciola G et al, ApplMHlCN.MH,G2(2): 191-204.[12] Kiselev A. V., Nikitin Y. S., Petrova R. S. Et al., Anal. Chem. [], 1964, 36: 1526.●12●Chinese Journal of Reactive PolymersJune 20, 2006[13] Voelkel A.. Grzes kowiak T, Colloid Surface A [], 2002, 208(1-3): 177~185.[14] Pokrxzovskiy V. A., Leboda R., Turov V. V. et al, Carbon [J], 1999, 37(7): 1039- -1047.[15] Gun'ko V. M., Leboda R., Pokrovskiy V. A. et al, J. Anal. Appl. Pyrol. [], 2001, 60(2):233~247.[16] Richard I. M., Principles of Sdsorption and Reaction on Solid Surfaces [M], New York:Wiley, 1996.[17] XI Hongxia, LI Zhong, Zhang Haibin, Li Xiang, Hu Xijun, Sep. Purif. Technol. [], 2003,31(1): 39~43.[18] LI Zhong, WANG Hongjuan, XI Hongxia et al, Adsorpt. Sci. Technol. [], 2003, 21(2):125~132.[19] Xia Qibin, Li Zhong, Xi Hongxia, Xu Kefeng, Adsorpt. Sci. Technol. [], 2005, 23(5):357~366.[20] Park J. H.. Yang R. T. Langmuir [J], 2005, 21(11): 5055-5060.[21] Eva D., Salvador O., Aurelio V. et al., J. Chromatogr: A [J], 2004, 1049(1-2): 139~146.[22] Eva D., Salvador O., Aurelio V. Et al., Micropor: Mesopor Mat. [J],2004, 70(1-3): 109~118.[23] Jinhai Xie, Qingin Zhang, Karl T. Chuang, J. Catal. [J], 2000, 191(1): 86~92.[24] Peter J., Bernard R., Vaclav K. B., J. Chromatogr A [J], 2002, 969): 301.[25] Boutboul Aurelia, Lenfant Francine, Giampaoli Pierre et al, J. Chromatogr: A [J], 2002,969(1-2): 9~16.[26] Ays eg"ul Askin, Ceyda Bilgic., Chem. Eng. J. [], 2005, 112(1~3): 159~165.[27] Diaz Eva, Ord6nez Salvador, Vega Aurelio et al, J. Chromatogr A [J], 2004, 1049(1-2):161~169[28] Bilgic Ceyda, Askin Aysegul, J. Chromatogr A [0, 2003, 1006(1-2): 281~286.[29] Onjia A. E., Milonjic S. K., Todorovic M. et al.J. Colloid Interf. Sci. [J],2002,251(1):10~17.[30] Xie Jinhai, Bousmina Mosto, Xu Guoying et al., J. Mol. Catal. A-Chem. [], 1998, 135(2):187~197.[31] Hadjar H., Balard H., Papirer E., Colloid Surface A [J], 1995, 99(1): 45~51.[32] Timsek Fatma, Inel Oguz, Chem. Eng. J. [], 2003, 94(1): 57~66.[33] Eder F, Lercher J. A., J. Phys. Chem. B [], 1997, 101(8): 1273~1278.[34] McCullen S. B., Reischman P. T, Olson D. H, Zeolites [J], 1993, 13(8): 640~644.[35] Ralph T. Yang, ADSORBENTS: Fundamentals and Applications, Hoboken [M], New Jersey:Wiley, 2003.中国煤化工MYHCNMHG