CTMAB/凹凸棒土颗粒的制备及其吸附Cr(Ⅵ)性能研究
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摘要
以凹凸棒土粉末为原料经一定工艺制得凹凸棒土颗粒,采用阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)为改性剂,通过微波改性合成了CTMAB/凹凸棒土颗粒,确定了最佳制备工艺条件为煅烧温度550℃,改性剂浓度80 mmol/L,微波改性时间6 min。考察了Cr(Ⅵ)溶液初始浓度和p H的影响,当Cr(Ⅵ)溶液浓度为20 mg/L,p H=5.6,CTMAB/凹凸棒土颗粒投加量为4 g/L时,在最佳条件下制备的CTMAB/凹凸棒土颗粒对Cr(Ⅵ)的去除率为90.7%。结果表明:改性后CTMAB进入到了凹凸棒土颗粒的表面及孔道,使其所带电性由负转为正,因而对以阴离子重铬酸根存在的Cr(Ⅵ)有更好的吸附性能,且Zeta电位随p H升高而降低,与去除Cr(Ⅵ)效率变化一致。吸附过程符合Langmuir等温线和Lagergren准二级速率方程,表明吸附为一种快速的单分子层化学吸附。
Powder attapulgite as a raw material was used to make the granular attapulgite,then granular attapulgite was modified with the surfactant of cetyltrimethylammonium bromide(CTMAB)by microwave modification to obtain the granular CTMAB/attapulgite,and it was found that the optimal conditions for preparing method were that the calcination temperature550 ℃,the surfactant concentration 80 mmol/L,the time of microwave 6 min. The effects of initial concentration and p H of Cr(Ⅵ)solution were investigated,and it was showed that when the concentration of Cr(Ⅵ)was 20 mg/L,p H was 5.6 and the dosage was 4 g/L,the removal efficiency of Cr(Ⅵ)by granular CTMAB/attapulgite was 90.7%. The results showed that CTMAB had either entered the interlayer or sorbed on the external surface of the granular attapulgite,making the Zeta potential of granular attapulgite become positve from negtive to have better adsorption properties for dichromate. The Zeta potential of granular CTMAB/attapulgite decreased with the increase of p H,consistent with the removal of Cr(Ⅵ)with p H.The adsorption process was found to fit Langmuir isotherm model and pseudo second-order rate equations,indicating that the adsorption model was a faster and monomolecular layer adsorption.
Powder attapulgite as a raw material was used to make the granular attapulgite,then granular attapulgite was modified with the surfactant of cetyltrimethylammonium bromide(CTMAB)by microwave modification to obtain the granular CTMAB/attapulgite,and it was found that the optimal conditions for preparing method were that the calcination temperature550 ℃,the surfactant concentration 80 mmol/L,the time of microwave 6 min. The effects of initial concentration and p H of Cr(Ⅵ)solution were investigated,and it was showed that when the concentration of Cr(Ⅵ)was 20 mg/L,p H was 5.6 and the dosage was 4 g/L,the removal efficiency of Cr(Ⅵ)by granular CTMAB/attapulgite was 90.7%. The results showed that CTMAB had either entered the interlayer or sorbed on the external surface of the granular attapulgite,making the Zeta potential of granular attapulgite become positve from negtive to have better adsorption properties for dichromate. The Zeta potential of granular CTMAB/attapulgite decreased with the increase of p H,consistent with the removal of Cr(Ⅵ)with p H.The adsorption process was found to fit Langmuir isotherm model and pseudo second-order rate equations,indicating that the adsorption model was a faster and monomolecular layer adsorption.
引文
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[2]Rai D,Zachara J M,Eary L E.Environmental chemistry of chromium[J].Science of the Total Environment,1989,86(1/2):15-23.
[3]李琛,葛红光,宋凤敏,等.改性玉米芯吸附柱处理含Cr6+废水的试验研究[J].水处理技术,2013,39(10):23-26.Li Chen,Ge Hongguang,Song Fengmin,et al.Experimental research on chromium-containing wastewater treatment with modified corncob adsorption column[J].Technology of Water Treatment,2013,39(10):23-26.
[4]Hu Bingjie,Luo Hanjin.Adsorption of hexavalent chromium onto montmorillonite modified with hydroxyaluminum and cetyltrimethyl ammonium bromide[J].Applied Surface Science,2010,257(3):769-775.
[5]左卫元,仝海娟,史兵方.改性活性炭对废水中铬离子的吸附[J].环境工程学报,2015,9(1):45-50.
[6]蒋立群,张瑞金,邓慧萍.颗粒活性炭改性同步去除水中铅、铬的研究[J].环境科学与技术,2014,37(12):178-181.Jiang Liqun,Zhang Ruijin,Deng Huiping.Adsorption removal of Pd(Ⅱ)and Cr(Ⅵ)from aqueous solutions by modified granular activated carbon[J].Environmental Science&Technology,2014,37(12):178-181.
[7]赵忠林,李鹏飞,马静红,等.凹凸棒土粘结剂对13X分子筛吸附性能的促进作用[J].离子交换与吸附,2008,24(1):25-32.Zhao Zhonglin,Li Pengfei,Ma Jinghong,et al.Improvement effect of attapulgite binder on the adsorption properties of zeolite 13X adsorbent[J].Ion Exchange and Adsorption,2008,24(1):25-32.
[8]金钦汉.微波化学[M].北京:科学出版社,1999.Jin Qinhan.Microwave Chemistry[M].Beijing:Science Press,1999.
[9]Stathi P,Papadas IT,Enotiadis A,et al.Effects of acetate on cation exchange capacity of a Zn-containing montmorillonite:physicochemical significance and metal uptake[J].Langmuir,2009,25(12):6825-6833.
[10]Demiral H,Demiral I,Tumsek F,et al.Adsorption of chromium(Ⅵ)from aqueous solution by activated carbon derived from olive bagasse and applicability of different adsorption models[J].Chemical Engineering Journal,2008,144(2):188-196.
[11]Malik P K.Dye removal from wastewater using activated carbon developed from sawdust:adsorption equilibrium and kinetics[J].Journal of Hazardous Materials,2004,113(1/2/3):81-88.