The pollution caused by toxic metal ions on ecosystems, agriculture and human health has attracted worldwide attention. Cr(VI) has detrimental effects on livers, lungs, kidney and nervous systems of mammals. Thus, the removal of Cr(VI) ions from wastewater are very important. Cr(VI) occurs as CrO42?, HCrO4?, Cr2O72? and HCr2O7? in aqueous solution. The surface of natural bentonite is negatively charged and has a small adsorption capacity for anions. The natural bentonite is powdery and difficult to separate from treated aqueous solutions. To improve the adsorption performance and application performance of bentonite to Cr(VI), the polyacrylic acid aluminum modified bentonite composite was prepared according to the following steps. Bentonite was modified with aluminum chloride hexahydrate, the polyacrylic acid-modified bentonite was prepared by polymerization of acrylic acid with aluminum modified bentonite in aqueous solution, and the polymer product were modified with hexadecyl trimethyl ammonium bromide (CTMAB) in aqueous solution. The characteristics of natural bentonite and modified bentonite were determined by XRD, FT-IR and SEM. Batch adsorption of Cr(VI) onto modified montmorillonite was investigated. The results showed that aluminum, acid monomers and CTMAB had intercalated into bentonite interlayers, and did not destroy the basic structure of natural bentonite. The adsorption capacity of Cr(VI) was 1.996 mg/g for 200 mL initial concentration of 20 mg/L by 0.5 g adsorbent at 25℃. The adsorption process to Cr(VI) was corresponding with the Lagergren secondary adsorption kinetics equation, chemical adsorption was the main control step. The adsorption capacity of the adsorbent increased with increasing the initial concentration of Cr(VI). The equilibrium adsorption capacity of the adsorbent for different concentrations of Cr(VI) was corresponding with the Freundlich isotherm equation. The adsorption of Cr(VI) onto the composite bentonite was multimolecular layer adsorption. The adsorption of Cr(VI) by granular adsorbent was mainly complexation reaction adsorption.
[1]Soliemanzadeh A, Fekri M.The application of green tea extract to prepare bentonite-supported nanoscale zero-valent iron and its performance on removal of Cr(VI): Effect of relative parameters and soil experiments Microporous MesoporousMater,2017,239: 6069[J].Microporous and Mesoporous Materials, 2017, 239(0):60-69
[2]Maity J, Ray S K.Enhanced adsorption of Cr(VI) from water by guar gum based composite hydrogels Int?J?Biol.?Macromol.,2016,89: 246255.[J].International Journal of Biological Macromolecules, 2016, 89(0):246-255
[3]Yang D, Zhao X, Zou X, et al.Removing Cr (VI) in water via visible-light photocatalytic reduction over Cr-doped SrTiO3nanoplates Chemosphere,2018,215: 586595[J].Chemosphere, 2018, 215(0):586-595
[4]Rezaei R, Massinaei M, Zeraatkar Moghaddam A.Removal of the residual xanthate from flotation plant tailings using modified bentonite MinerEng,2018,119: 110.[J].Minerals Engineering, 2018, 119(0):1-10
[5]Wei S T, Ting A S Y.Alginate-immobilized bentonite clay: Adsorption efficacy and reusability for Cu(II) removal from aqueous solution Bioresour?Technol,2014,160: 115118.[J].Bioresource Technology, 2014, 160(0):115-118
[6]Anirudhan T S, Tharun A R.Preparation and adsorption properties of a novel interpenetrating polymer network (IPN)containing carboxyl groups for basic dye from aqueous media. Chemical Engineering Journal.[J].2012, 181182: 761-769[J].Chemical Engineering Journal, 2012, 181-182(0):761-769
[7]徐迎雪.悬浮乳液法制备粒状聚丙烯酸-丙烯酸钠钙基复合膨润土及其性能研究[J].河北工业大学, 2014, 0(0):40-41
[8]Xu Y X.Study on synthesis of granular poly (acrylic acid-sodium acrylate) bemtonite composite by means of suspension Polymerization and its properties[J].Hebei University of Technology, 2014, 0(0):40-41
[9]曹春艳.改性膨润土吸附处理含六价铬废水的研究[J].化学工程师, 2008, 0(10):43-45
[10]Cao C Y.Study on adsorption treatment of wastewater containing hexavalent chromium by modified bentonite Journal of Chemical Engineers,2008,(10): 4345[J].Journal of Chemical Engineers, 2008, 0(10):43-45
[11]孙胜龙, 赵晓明.钠、铝改造型膨润土对溶液中Ⅵ吸附及其机理研究[J].水处理技术, 1999, 25(5):344-349
[12]Sun S L, Zhao X M.Adsorption of Cr(VI) on sodium and aluminum modified bentonite in solution and its mechanism[J].Technology of Water Treatment, 1999, 25(5):344-349
[13]El-Korashy S A, Elwakeel K Z, El-Hafeiz A A.Fabrication of bentonitethiourea-formaldehyde composite material for Pb(II),Mn(VII) and Cr(VI) sorption: A combined basic study and industrial application JClean. Prod.,2016,137: 40-50.[J].Journal of Cleaner Production, 2016, 137(0):40-50
[14]游鑫玲.聚丙烯酸-丙烯酸钠复合膨润土的制备及其性能研究 [D]. 天津: 河北工业大学, 2013, 49.
[15]You X Y.Study on synthesis of the poly(acrylic acid-sodium acrylate) bemtonite composite and its properties [D]. Tianjin Hebei University of Technology, 2013, 49.
[16]Wang X Z, Cao J L, Chen X Q.Synthesis of composite bentonite and its adsorption to fluorine ion Environ?Sci.?Technol.,[J].Environmental Science and Technology, 2011, 34(1):65-69
[17]You X L, Cao J L, Liu X W.Synthesis of the Poly(Acrylic Acid-Acrylic Sodium) Bentonite Composite and Its Adsorption of Cd(II)[J].Asia. Pac. J. Chem. Eng., 2017, 12(1）.[J].Asia-Pacific Journal of Chemical Engineering,2017,12（1):0-0
[18]Hu B J, Luo H J.Adsorption of hexavalent chromium onto montmorillonite modified with hydroxyaluminum and cetyltrimethylammonium bromide[J].Appl. Surf. Sci.I, 2010, 257(3):769-775
[19]Leonid Perelomov a, Binoy Sarkar, Anastasia Goryacheva, et al.Perelomov L,Sarkar B,Rahman M M,et alUptake of lead by Na-exchanged and Al-pillared bentonite in the presence of organic acids with different functional groups[J].Applied Clay Science, 2016, 119(0):417-423
[20]Perelomov L, Sarkar B, Rahman M M.Uptake of lead by Na-exchanged and Al-pillared bentonite in the presence of organic acids with different functional groups[J].Applied Clay Science, 2016, 119(0):417-423
[21]邵红, 张广兴, 李云娇, 等.复合改性膨润土制备及氨氮废水的吸附处理试验[J].净水技术, 2017, 36(11):55-61
[22]Shao H, Zhang G X, Li Y J, et al.Preparation of SDSAl3+ composite modified bentonite and adsorption treatment of ammonia nitrogen wastewater[J].Water Purification Technology, 2017, 36(11):55-61
[23]聂锦旭.改性膨润土吸附剂的制备及其在废水处理中的应用 [D]. 广州： 中国科学院研究生院(广州地球化学研究所), 2003, 19(1): 99-102.
[24]Nie J X.Modified Bentonite Absorbent Preparation and Application in Wastewater Treatment [D]. Guangzhou: Guangzhou Institute of Geochmistry, Chinese Academy of Sciences，Guangzhou, P, R, China for the degree of Doctor of Environment, 2003, 19(1): 99-102.
[25]Moussout H, Ahlafi H, Aazza M, et al.Performances of local chitosan and its nanocomposite 5%BentoniteChitosan in the removal of chromium ions (Cr(VI)) from wastewater Int.?J.?Biol.?Macromol.,2017,108: 1063-1073.[J].International Journal of Biological Macromolecules, 2017, 108(0):1063-1073
[26]Witono J R, Noordergraaf I W, Heeres H J, et al.Water absorption,retention and the swelling characteristics of cassava starch grafted with polyacrylic acid[J].Carbohydr.?Polym., 2014, 103(1):325-332
[27]杨浩.聚(丙烯酸-丙烯酸钠)复合膨润土改性及其性能研究 [D]. 天津: 河北工业大学, 2015, 3738.
[28]Yang H.Study on sythesis of the modified Poly(acrylic acid-acrylic sodiym)bentonite composite and its properties[D]. Tianjin: Hebei University of Technology, 2015, 37-38
[29]Azha S F, Shahadat M, Ismail S.Acrylic polymer emulsion supported bentonite clay coating for the analysis of industrial dye Dyes Pigments,2017,145: 550-560.[J].Dyes and Pigments, 2017, 145(0):550-560
[30]Ren Y, Abbood H A, He F, et al.Magnetic EDTA-modified ChitosanSiO2Fe3O4 Adsorbent: Preparation,Characterization,and Application in Heavy Mmetal Adsorption[J].Chem. Eng. J., 2013, 226(12):300-311
[31]Bansiwal A, Thakre D, Labhshetwar N.Fluoride Removal Using Lanthanum Incorporated Chitosan Beads[J].Colloids Surf. B., 2009, 74(1):216-224
[32]Xu L Y, Chen G J, Peng C Y.Adsorptive removal of fluoride from drinking water using porous starch loaded with common metal ions[J].Carbohydrate Polymers, 2017, 160(0):82-89
