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

Transactions of Tianjin University[ISSN:1006-4982/CN:12-1248/T]

Issue:
2011年01期
Page:
51-56
Publishing date:

Info

Title:
Determination of Diffusion Coefficient and Analysis of Diffusion Factors of Cr(Ⅵ) Ion in Clay Soil*
Author(s):
YANG Qinglei 12ZHANG Jinli 12YANG Qing 12 TANG Xiaowei 12YU Yongxian 3YANG Gang 12
1. State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China; 2. Institute of Geotechnical Engineering, School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China; 3. School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
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DOI:

Abstract:
Some laboratory diffusion tests were conducted with diffusion device to determine the diffusion coeffi- cient 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 trans- port equation was used to simulate the transport of Cr(Ⅵ) through clay samples. Back-calculation of diffusion coeffi- cient 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.

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Last Update: 2011-04-07