十八烷基三甲基氯化铵/双十八烷基二甲基氯化铵修饰ATP的制备及其吸附重金属的性能

Adsorption of lead(Ⅱ) ions in waste water on acid-treated attapulgite

使用12 mol/L的盐酸对天然凹凸棒石晶体(ATP)进行粗提处理,再用十八烷基三甲基氯化铵(DOTAC)和双十八烷基二甲基氯化铵(DODMAC)分别对ATP进行接枝改性,得到十八烷基三甲基氯化铵改性凹土(1831-ATP)和双十八烷基二甲基氯化铵改性凹土(D1821-ATP)。通过红外光谱(FT-IR)、X射线衍射(XRD)和比表面积(BET)等表征手段对改性前后凹土的晶体结构变化进行分析比较,并利用扫描电镜(SEM)观察了ATP、1831-ATP和D1821-ATP的形貌变化。对比研究了ATP、1831-ATP和D1821-ATP对常见重金属Pb2+的吸附性能,吸附实验结果表明:吸附平衡时间为4 h;在p H 9时,Pb2+在ATP、1831-ATP和D1821-ATP上的吸附量达到最高,去除率均达到99%以上,去除效果好。动力学和热力学模型拟合结果表明,吸附数据符合准二级动力学方程和Freundlich等温吸附方程。

ATP was prepared by treating natural attapulgite with acid,and then modified by the cationic surfactants octade cyltrimethyl ammonium chloride and dimethyldistearylammonium chloride to prepare 1831-ATP and D1821-ATP,respectively. The effects of varying p H,time and ion concentration on the sorption efficiency of lead（ Ⅱ） on attapulgite were investigated in batch experiments and the thermodynamic and dynamic laws of the sorption were studied. The results showed that the sorption was strongly p H-dependent and ion concentration had little impact on sorption. The sorption process can be described by a pseudo-second-order rate model. The Freundlich model fitted the sorption data better than the Langmiur model. Since the adsorption process is not described primarily by monolayer and chemical adsorption,the adsorption of lead（ Ⅱ） on 1831-ATP is better than that on ATP from the view point of both capacity and rate.