Determination of Diffusion Coefficient and Analysis of Diffusion Factors of Cr(Ⅵ) Ion in Clay Soil  

作　　者：杨清雷 张金利 杨庆 唐小微 于永鲜 杨钢 

机构地区：[1]State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology [2]Institute of Geotechnical Engineering, School of Civil and Hydraulic Engineering,Dalian University of Technology [3]School of Chemical Engineering, Dalian University of Technology

出　　处：《Transactions of Tianjin University》2011年第1期51-56,共6页天津大学学报（英文版）

基　　金：Supported by National Natural Science Foundation of China (No. 50679015).

摘　　要：Some laboratory diffusion tests were conducted with diffusion device to determine the diffusion coefficient of Cr(Ⅵ) ion passing through Dalian red clay samples. The concentrations of Cr(Ⅵ) at different places of the samples were then measured spectrophotometrically after a standing time of 1 000 d. A one-dimensional solute transport equation was used to simulate the transport of Cr(Ⅵ) through clay samples. Back-calculation of diffusion coefficient of Cr(Ⅵ) was made with finite difference method. Parametric analysis was conducted to simulate variations in soil dry density, temperature, pH and standing time. The results show that the method used in this paper is simple and effective. The diffusion coefficient of Cr(Ⅵ) in Dalian red clay varies from 1.50×10-7 cm2/s to 2.08×10-7 cm2/s. After 1 000 d diffusion, the concentration of the source solution drops down to 1.27 mg/L from 62.5 mg/L, and the diffusion distance is only 3.5 cm. Under the assumption that diffusion coefficient is constant, the diffusion effect becomes more obvious with lower density, lower temperature, higher pH value, and much more time.Some laboratory diffusion tests were conducted with diffusion device to determine the diffusion coefficient of Cr（Ⅵ） ion passing through Dalian red clay samples. The concentrations of Cr（Ⅵ） at different places of the samples were then measured spectrophotometrically after a standing time of 1 000 d. A one-dimensional solute transport equation was used to simulate the transport of Cr（Ⅵ） through clay samples. Back-calculation of diffusion coefficient of Cr（Ⅵ） was made with finite difference method. Parametric analysis was conducted to simulate variations in soil dry density, temperature, pH and standing time. The results show that the method used in this paper is simple and effective. The diffusion coefficient of Cr（Ⅵ） in Dalian red clay varies from 1.50×10-7 cm2/s to 2.08×10-7 cm2/s. After 1 000 d diffusion, the concentration of the source solution drops down to 1.27 mg/L from 62.5 mg/L, and the diffusion distance is only 3.5 cm. Under the assumption that diffusion coefficient is constant, the diffusion effect becomes more obvious with lower density, lower temperature, higher pH value, and much more time.

关 键 词：LANDFILL Cr(Ⅵ) ion TRANSPORT clay soil diffusion coefficient 

分 类 号：X502[环境科学与工程—环境工程]