高岭土界面电化学性能及其对重金属的吸附研究  

Interface Electrochemical Characteristics in Kaolinite and Its Effect on the Adsorption Properties to Heavy Metal

作　　者：张树芹[1] 路福绥[1] 姜林[1] 

机构地区：[1]山东农业大学化学与材料科学学院,山东泰安271018

出　　处：《山东农业大学学报（自然科学版）》2014年第5期675-679,685,共6页Journal of Shandong Agricultural University：Natural Science Edition

基　　金：山东省自然科学基金(ZR2009DM032);山东省博士基金(2008BS07016);山东农业大学青年创业基金(23621)

摘　　要：分别采用质量滴定法（MT）、电势滴定法（PT）测定了荷结构负电荷的高岭土的零电荷点，MT法与PT法的实验结果分别为：3.70±0.05和2.16，质量滴定法结果明显高于电位滴定法。结合表面络合模型推算了表面位密度（Ns）及各特征络合平衡常数pK、pK 、pK 。研究了Pb2＋在高岭土上的吸附性能，考察了pH值、离子强度等因素对吸附量的影响，并探讨了吸附机理。高岭土吸附Pb2＋的动力学曲线符合准二级动力学方程，吸附等温线符合Langmuir方程。Pb2＋同时以内层络合和外层络合形式吸附，其相对量与pH有关；在pH小于4和大于8的范围内，内层络合物为主，而pH在4-8范围内外层络合物比例增大。The point of zero charge of the kaolinite with structural negative charge was measured by mass titration and potentiometric titration. Result shows that the rage of PZC for MT method was 3.70±0.05 which was significantly higher than PT method （2.16）. According to the surface complexation model the surface site density and intrinsic surface reaction equilibrium constants （pK、pK 、pK 、） were calculated. Adsorption properties of Pb2 ＋on kaolinite were studied, the influence of solution pH and ion strength on the adsorption of Pb2＋ were investigated, and the adsorption mechanism was discussed. The adsorption kinetics of Pb^2＋ on kaolinite can be described by the pseudo-second-order kinetics equation, the adsorption isotherms fitted well with Langmuir. The adsorption mechanism of Pb^2＋ on kaolinite is the surface complex mechanism, simultaneously forming inner-sphere surface complexes and outer-sphere surface complexes. The relative content of outer-sphere surface complexes is dependent of pH, and that in the pH range of 4-8 is higher than in the pH ranges of lower than 4 and higher than 8, respectively.

关 键 词：质量滴定 电位滴定 高岭土 PB^2+ 吸附 

分 类 号：O647[理学—物理化学]