HTMAC改性膨润土吸附水中六价铬的动力学和热力学研究

Kinetics and Thermodynamics Study on Adsorption of Cr(Ⅵ) in Aqueous Solution Using HTMAC Modified Bentonite

采用十六烷基三甲基氯化铵(HTMAC)作为有机改性剂制备有机改性膨润土(HTMAC-Bent),并将其用于水中六价铬的吸附研究。通过伪二级动力学模型、粒子内部扩散模型和耶洛维奇模型等3种动力学模型、Langmuir吸附等温线方程和Freundlich等温线方程等2种吸附等温模型分别研究其动力学及热力学行为。线性拟合的研究结果,伪二级动力学方程最符合描述HTMAC-Bent对水中六价铬的吸附过程(相关系数R2均超过0.999),表明该过程是一个物理-化学作用为主的吸附过程。与Langmuir等温线方程相比,在所研究的温度范围内,Freundlich吸附等温模型更好地描述HTMAC-Bent对水中六价铬的等温吸附过程(相关系数R2均大于0.991),证实HTMAC-Bent对水中六价铬的过程属于多层吸附类型,也属于一种自发地无序的吸热过程。

N-Hexadecyltrimethylammon（HTMAC） was used to be an organic modifier,N-Hexadecyltrimethylammon modified benonite（HTMAC-Bent） was prepared and it was exploited to adsorb hexavalent chromium（Cr（Ⅵ）） in aqueous solution.The kinetics equations of Pseudo-second-order,Intraparticle diffusion and Elovich were used to describe adsorption process of Cr（Ⅵ） using HTMAC-Bent,both of Langmuir and Freundlich isotherm models were also utilized to evaluate adsorption process of Cr（Ⅵ） using HTMAC-Bent. The kinetics results showed that pseudo second-order equation was the best fitted with the adsorption process and all of the correlation coefficients（R2） were more than 0. 999.It confirmed that this process is a kind of physicochemical adsorption.Thermodynamics results displayed that Freundlich adsorption isothermal model was better than that of Langmuir adsorption isotherm models to describe the adsorption process with the correlation coefficient（R2） greater than 0. 991. Therefore,the adsorption process of Cr（Ⅵ） in aqueous solution using HTMAC-Bent belong to multilayer adsorption process,and is also a kind of spontaneously disorderedly endothermic process.