Dieldrin and endrin removal from water by triolein-embedded adsorbent Dieldrin and endrin removal from water by triolein-embedded adsorbent

Dieldrin and endrin removal from water by triolein-embedded adsorbent

  • 期刊名字:科学通报(英文版)
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  • 论文作者:HUO Jinxian,LIU Huijuan,QU Jiu
  • 作者单位:State Key Laboratory of Environmental Aquatic Chemistry
  • 更新时间:2020-07-08
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论文简介

ARTICLESChinese Science Bulletin 2005 Vol. 50 No. 23 2696- -2700related to octanol-water coefficients and adsorptiveDieldrin and endrin removalcapacities of adsorbents on pollutants with higher octanol-water coefficients are larger than those with lower 0C-from water by triolein-tanol-water cofficients. Octanol-water ceofficients ofpollutants can be attributed to different solubilities. So it isembedded adsorbentmeaningful to compare different factors affecting adsorp-tion behaviors of different pollutants.In this paper, equilibrium adsorption capacities of diel-HUO Jinxian, LIU Huijuan, QU Jiuhui, RU Jia,drin and endrin, and adsorption rates under different op-LIU Haining & LI Guotingeration conditions are investigated using triolein-embe-State Key Laboratory of Environmental Aquatic Chemistry, Research dded adsorbent made in lab so as to understand the ad-Center for Eco-environmental Science, Chinese Academy of Sciences,sorption behaviors for different pollutants.Beijing 100085, ChinaCorrespondence should be adressed to Qu Jiuhui (email: jhqu@ mail.1 Experimental detailsrcees.ac.cn)1.1 Preparation of triolein-embedded adsorbentAbstract A novel triolein-embedded adsorbent for re-Triolein-embedded adsorbent was prepared by coveringmoval of persistent organic pollutants (POPs) from waterthe triolein/cellulose acetate (CA) composite membranewas developed. In this paper, taking dieldrin and endrin ason the spherical silica gel, and then was washed with dis-the target pollutants, different factors (temperature, iontlled water repeatedly until total organic carbon (TOC) ofstrength, pH, and concentration of humic acid) that affectthe adsorption rate were investigated. Adsorption isothermsthe leachate was near that of ditilled water. Cross sectionof these two pollutants ftted to Freundlich model well identi- of triolein-embedded adsorbent was observed by scanningfied the partition mechanism between the adsorbent and electron microscope (SEM), as shown in Fig. 1, whichwater. However, the equilibrium constant of dieldrin was indicated that distinct interface between the compositelarger than that of endrin due to larger octanol-water coeffi-membrane and silica gel did not present and compositecient of dieldrin. Adsorption rate of dieldrin increased withmembrane covered the surface of silica gel tightly. Thethe increase of temperature, the decrease of ion strength, pHadsorbent diameter is about 2- 5 mm, real density in wetand concentration of humic acid, whereas adsorption rate ofendrin decreased with the increase of temperature and pH.tate is about 1.22 g mL", and water content is aboutHumic acid firstly increased, and then decreased the adsorp- 0.405.tion rate of endrin. Ion strength hardly affected the adsorp-tion rate of endrin.ldrin, endrin,nol-water coefficient, triolein- embe-KeywordsiDOI: 10.1360/982005-471POPs, which are prone to produce toxic effects due totheir highly accumulation inside of aquatic organism, arehardly degraded and exist in environment during a longperiod, although they have low concentration in water(usu. from ng L' to pg L-I1.2). The production of POPshas been banned, however, some formerly produced POPsare continuously being used. POPs in trace amount cannotbe removed effectively using present water treatmentVD25-1mn20-0KV 5001001mtechniques. Active carbon, which is used extensively toremove organic pollutants from water, cannot ideally re-Fig. 1. Cross section image of triolein-embedded adsorbent.move organic halogenide with the concentration lowerthan 5 μg L5. Much attention has been paid to the1.2 Physicochemical properties of dieldrin and endrinhighly accumulated capacity of triolein for hydrophobicBoth dieldrin and endrin are chlorinated cyclic hydro-organic pollutants and many relevant reports have beencarbon and commonly belong to cyclodience insecticides.presented, but most previous researches focused on theTheir physico中国煤化工wn in Table 1.fields such as environmental monitoring and toxicity4- 81.1.3 ExperinReports on using triolein as a component of adsorbent toTHCNMH Gremove POPs from water are seldom presented.Solution Containng certan analyle (400 mL) wasMany researches proved that the adsorption of the hy-freshly prepared with distilled water. AIll samples weredrophobic organic pollutants on adsorbents is positivelyshaken for 24 h at temperature of 25 Cwith rotating speed2696Chinese Science Bulletin Vol. 50 No. 23 December 2005ARTICL .ESTable 1 Physicochemical properties of dieldrin and endrinof adsorbate (dimensionless) and is calculated accordingPhysicochemical propertiesDieldrinEndrinto eq. (2):Molecular weight380.9C,=CJSw,(2)Melting pointU C175- - 176245where Ce is the equilibrium concentration of adsorbate irDensity (relative to water)1.751.65 .solution (μg L) and Sw is the solubility of adsorbateSolubilityig L'18612120001(μg L'). K; with the same dimension can be comparedOctanol-water coefficient10-481911045691directly when values of n are different.of 160 rpm before adsorption experiment. Timing began periment data of adsorption isotherms of dieldrin and en-the moment the adsorbent was added to the solution. At drin are ftted well with modified Freundlich model (R2 >selected time intervals, up to a maximum of 24 h, 10 mL0.99), which indicates that partition between adsorbentof solution was sampled and the concentration of analyteand water is the major adsorption mechanism of dieldrinwas analyzed by GC-ECD. In addition, experiments with and endrin. n of endrin is close to that of dieldrinrespect to sorption isotherm were carried out to assess the indicating that adsorption isotherm of two adsorbates deremoval capacity of triolein-embedded adsorbent for diel-viates from linearity at the same degree, which may bedrin or endrin in water. For the adsorption equilibrium,attributed to their similar chemical structures. However,samples of wet adsorbents (1一10 g) were equilibrated the adsorption capacity of dieldrin is larger than that ofwith 150 mL solution with an initial concentration of 100 endrin due to its higher octanol-water coefficient.μg L' diedrin or endrin. The equilibration was carried outat temperature of 25C for one week by shaking con-Table 2 Parameters of adsorption equilibrium of dieldrin and endrin ontriolein- embedded adsorbentstantly. Adsorbed analyte capacity on triolein-embeddedadsorbent was determined from the difference betweennR2K"K';initial and equilibrium concentration in aqueous solution.0.8760.990376.9340.874 0.9927 70.2171.4 Analysis methodResidual pollutants in water were extracted with12-n-hexane. One microlitre aliquot of extraction was ana-lyzed using HP6890 capillary gas chromatography-elec-)-tron capture detector (GC-ECD) system under the follow-8-ing conditions: A HP-5 fused silica capillary column (30mX 0.32 mm I.D., film thickness of 0.25 μm) was fitted ins-the instrument. The injector temperature was set to 250C.4-The ECD was maintained at 280C. The temperature ofGC oven was programmed as follows: 85 "C, isothermalfor 2 min, then the temperature was raised at 25°C min~-to 240"C, followed by 5"C min~ 1 to 280°C and held at 2800.000.050.100.15°C for 10 min. High-purified nitrogen was used as thecarrier gas at a head pressure of 16 psi. .Fig. 2. Adsorption isotherm of dieldrin and endrin at 25C.■, Diel-For the quality control of gas chromatographic condi- drin; O. Endrin;, fixed curves.tions, a checkout procedure was performed before sampleanalysis. In the procedure, the calibration was carried out2.2 Effect of different factors on adsorption ratewhen the concentration in standard solution deviated sig-Resistance of mass transfer or resistance of thermalnificantly from 15%. To insure free of hangover, two re-transfer or two controls adsorption rate, so it is possibleagent blanks were done after analysis of 18 samples.that adsorption rate is affected by properties of adsorbate2 Results and discussionand solution, such as temperature, pH, ion strength andconcentration of resolvable organic pollutants.2.1 Adsorption isothermThe modified second-order model (eq. (3)) is exten-Adsorption equilibrium data of dieldrin and endrin onsively used to fit the experimental data by many research-triolein-embedded adsorbent were fited using modified ersl'1-131.. Int中国煤化工are also analyzedFreundlich model as eq. (1):by the modifgood correlationF=K"C",(1)coefficient, RMYHCNM HGwhere r is the sorption capacity at equilibrium (4g g );1__K"p is the modified Freundlich constant (dimensionless); n9=9°(|β2+kt(3)is the Freundlich constant; Cr is the relative concentrationChinese Science Bulletin Vol. 50 No. 23 December 20052697ARTICL .ESwhere qt is amount of adsorption at timet(ig g), qe is the adsorption rate vs. temperature are shown in Fig. 3(b).sorption capacity at equilibrium (ig g), kz is the rate Results indicate that temperature affects the adsorption ofconstant of adsorption (hi ),β2 related to surface cover- dieldrin and endrin at different degrees. Adsorption rate ofage is dimensionless constant. When surface coverage at dieldrin increases with thincrease of temperature, butpre-adsorbed stage is 0,β2is 1. t is the adsorption time adsorption rate of endrin decreases with the increase of(htemperature. This indicates that the increase of the tem-Eq. (4) can be obtained by differentiating eq. (3).perature is advantageous to the adsorption of dieldrin anddisadvantageous to the adsorption of endrin. For physicaldq,qe{β+(4) adsorption, increase of the temperature goes against thedt k2( k2adsorption. However, adsorption rate was affected notwhere it is the adsorption rate at time t (μg g! h). Eq.only by resistance of thermal transfer but also by that of(4) becomes eq. (5) att=0.mass transfer. Increase of the temperature leads to the de-crease of resistance of mass transfer, accordingly massvo=2(5transfer quickens. It is obvious that resistance of massβ2transfer affects the adsorption of dieldrin, and resistancewhere qe, k, β2 can be obtained by the modified secof mass transfer and thermal transfer commonly affects .ond-order model, so did io.the adsorption of endrin.Data of adsorbed amount at time t vs. time at differenttemperatures and their ftted curves are shown in Fig. 3(a).ion strength and their fitted curves are shown in Fig. 4(a).qe k2, βr2 are obtained by fitted curves, and then adsorp- qe k2, ir are obtained by fited curves, and then adsorp-tion rate at t=0 is calculated by eq. (5). The curves of tion rate at t=0 is calculated by eq. (5). The curves of ad-0.8-(a4- (b).2 t0.6-二1.0- -s一 Endrin0.4-0.2 .Dieldrin■515,▲25,▼35CEndrin0.2-0.012025;101520253035TrCFig.3. (a) Time function of adsorption capacity of dieldrin and endrin at different temperatures. - , Fixed curves; (b) temperature eft on initialadsorption rate of dieldrin and endrin.一- Dieldrin- - s- Endrin00 0.6-Dieldrin■1, ●10, ▲50, ▼100 mmol.L-lEndrin口1, 。10, 0 50,口100 mmol:L-1中国煤化工↓0.0+012:MYHCNMHG100t/NCI/IUI儿Fig. 4. (a) Time function of adsorption capacity of dieldrin and endrin at different ion strength. 一, fixed curves; (b) ion strength effect on initial ad-sorption rate of dieldrin and endrin.2698Chinese Science Bulletin Vol. 50 No. 23 December 2005ARTICL ESsorption rate vs. ion strength are shown in Fig. 4(b). Re- concentration of humic acid and their fitted curves aresults indicate that ion strength more largely affects theshown in Fig. 6(a). qe, k2, β2 are obtained by fitted curves,adsorption of dieldrin than that of endrin. The adsorptionand then adsorption rate at t=0 is calculated by eq. (5). .rate of dieldrin decreases with the increase of ion strength,The curves of adsorption rate vs. concentration of humicbut the adsorption rate of endrin firstly increases, and thenacid are shown in Fig. 6(b). As shown in Fig. 6(b), thedecreases with the increase of ion strength lightly. Differ-concentration of humic acid affects the adsorption of diel-ent solubility is the possible reason.drin and endrin at different degrees. The adsorption rate ofData of adsorbed amount at time t vs. time at differentdieldrin decreases with the increase of concentration ofpH and their fitted curves are shown in Fig.5(a). qe, k2,a2 humic acid, but the adsorption rate of endrin firstly in-are obtained by ftted curves, and then adsorption rate at creases, then decreases with the increase of the concentra-t=0 is calculated by eq. (5). The curves of adsorption ratetion of humic acid. This indicates that certain concentra-vs. pH are shown in Fig. 5(b). As shown in Fig. 5(b), ad-tion of humic acid increases the adsorption rate of endrin.sorption rate of endrin on triolein-embedded adsorbent In spite of the complex structure, it is the general idea thatdecreases with the increase of pH, the same as that of di- humic acid is the electronegative organic substance. Hueldrin. CA is the polymer with acetyl group and hydroxyImic acid affects adsorption rate of strong hydrophobicgroup. It is the general idea that acetyl group is the hy-pollutants more than that of weak hydrophobic pollutants.drophobic group and hydroxyl group is the hydrophilic Adsorption rate of dieldrin obviously is larger than that ofgroup. Increase of pH leads to the loss of the proton of endrin when concentration of humic acid is low. Increasedhydroxyl group, accordingly changes the surface propertyconcentration of humic acid leads to the increase of ad-of membrane and decreases the adsorption rate. At thesorption rate of endrin. So it is possible that decrease ofsame pH, adsorption rate of dieldrin always overtops that humic acid in water is advantageous to adsorption ofof endrin due to their different solubility.strong hydrophobic pollutants and increase of humic acidData of adsorbed amount at time t vs. time at different is advantageous to that of weak hydrophobic pollutants.(a0.6b)E= 0.5-- Dieldrin骂? 0.40.4-1- Endrin0.DieldrinEndrin:g;:o。2:号0.30.0 +0 15202:78/pHFig. 5. (a) Time function of adsorption capacity of dieldrin and endrin at different pH. - , fixed curves; (b) pH effect on initial adsorption rate ofdieldrin and endrin.0.8-- - Dieldrin-s- Endrin与0.6-R 0.4-望0.5-0.2-Dieldrin■0.●2,▲5,▼8mgL'0.3-; mg.L-1中国煤化工_0.0-152(HMHCNMHGthCHAig'LFig. 6. (a) Time function of adsorption capacity of dieldrin and endrin at different concentration of humic acid.- , fixed curves; (b) Humic acid concen-tration affect on initial adsorption rate of dieldrin and endrin.Chinese Science Bulletin Vol. 50 No. 23 December 20052699ARTICLES3 Conclusions4. John, C. M., Kathy, R. E, Huckins, J. N., Estimation of uptake rateAnalysis of experimental data was carried out usingconstants for PCB congeners accumulated by semipermeableFreundlich model and the modified second-order model.membrane devices and brown trout (Salmo trutta), Environ. Sci.The following conclusions can be obtained:Technol, 1998, 32(12): 1847-1852.Adsorption isotherms of dieldrin and endrin on tri-5. Robert, W. G., Huckins, J. N., Petty, J. D.,. Comparison of the up-olein-embedded adsorbent show that different solubility ofdieldrin and endrin will lead to different adsorption capac-take of dioxin-like compounds by caged channel catfish andity. The adsorption capacity of dieldrin higher than that ofsemipermeable membrane devices in the Saginaw River, Michigan.endrin can be attributed to high octanol-water coefficientEnviron. Sci. Techno.,. 1997, 31(1): 178-187.of dieldrin.6. Petty, J. D., Huckins, J. N, Orazio, C. E., Determination of water-Temperature, ion strength, pH, and concentration ofborne bioavailable organochlorine pesticide residues in the lowerhumic acid affect the adsorption of dieldrin and endrin atthe different degrees due to their different hydrophobi-Missouri River, Environ. Sci. Technol., 1995, 29(10): 2561- 2566.cities, accordingly the different solubility. Temperature7. Hofel, C. s, Shea, D.. Accumulation of organochlorine pesticideslargely affects the adsorption of dieldrin. Adsorption rateand PCBs by semipermeable membrane devices and mytilus edulisof dieldrin increases with the increase of the temperature,in New Bedford Harbor, Environ. Sci. Technol, 1997, 31(1): 154-however, adsorption rate of endrin slowly decreases with59.the increase of the temperature. Ion strength suppresseshe adsorption of dieldrin, but certain ion strength pro-8. Booj, K, Drooge, B. L, Polychlorinated biphenyls and hexa-motes the adsorption of endrin. Adsorption rates of diel-chlorobenzene in atmosphere, sea-surface microlayer, and waterdrin and endrin eqully decrease with the increase of pH,measured with semi- permeable membrane devices (SPMDs),which indicates that increase of pH is disadvantageous toChemosphere, 2001, 44(2):91- -98.the removal of dieldrin and endrin. Humic acid suppresses .the adsorption of dieldrin, but certain concentration of9. Mackay, D., Correlation of bioconcentration factors, Environ. Sci.humic acid promotes the adsorption of endrin.Technol, 1982, 16(5): 274- -278.Acknowledgements This work was supported by the National Natural0. Jarvinen, A. W., Tyo, R. M.. Toxicity to fathead minnows of endrinScience Foundation of China (Grant No. 20337020), the Nationalin food and water, Arch. Environ. Contam. Toxicol, 1978, 7(4):High-Tech Research and Development Plan (Grant No.2005AA642020),and the China Postdoctoral Science Foundation.409- -421.References1. Lazaridis, N. K, Asouhidou, D. D., Kinetics of sorptive removal ofchromium (VI) from aqucous solution by calcined Mg-AI-CO3 hy-1. Louie, P. K. K., Sin, D. W., A preliminary investigation of persis-drotalcite, Water Res, 2003, 37(12): 2875- -2882.tent organic pollutants in ambient air in Hong Kong, Chemosphere,I2. Cheung, C. w., Porter, J. F.. Mckay, G., Sorption kinetic analysis2003, 52(9): 1397- -1403.2. Erguder, T. H., Guven, E, Demirer, G. N, The inhibitory effectsfor the removal of cadmium ions from effluents using bone char,and removal of dieldrin in continuous upflow anaerobic sludgeWater. Res, 2001, 35(3): 605- -612.blanket reactors, Bioresource Technology, 2003, 89(2): 191-197.13. Oxcan, A. S., Erdem, B., Orcan, A., Adsorption of Acid Blue 1933. Wang, Z. S.. Liu, W. J.. Drinking Water Treatments for Micropol-from aqueous solutions onto Na -bentonite and DTMA-bentonite,lutant Water Resources (in Chinese), Beijing: Construction Indus-Journal of Colloid and Interface Science, 2004, 280(1): 44- -54.try Press, 2001, 62.(Received March 29, 2005; accepted April 13, 2005)中国煤化工MHCNMH G2700Chinese Science Bulletin Vol. 50 No. 23 December 2005

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