不同含水量细砂介质中挥发苯的有效扩散系数研究  

Effective Diffusion Coefficient of Volatile Benzene in Medium of Fine Sands Different in Water Content

作　　者：高文谦[1] 刘菲[1] 陈鸿汉[1] 许文婕[1] 

机构地区：[1]中国地质大学水资源与环境工程北京市重点实验室,北京100083

出　　处：《生态与农村环境学报》2009年第1期69-72,共4页Journal of Ecology and Rural Environment

基　　金：中国科技部国际合作项目(2006DFA21180);国家自然科学基金(40372109;40572146)

摘　　要：挥发性有机污染物在土壤多孔介质中的有效扩散系数是土壤气相抽提(soil vapor extraction,SVE)传质过程中的一个重要参数。笔者以苯为研究对象,采用土柱扩散试验,对不同含水量条件下挥发苯在细砂介质中的有效扩散系数和扩散规律进行研究。结果表明,对于吸附型矿物含量少的细砂介质,含水量大小在一定程度上影响了挥发苯的扩散过程。含水量在50g.kg-1时,扩散最快;低于50g.kg-1时,随含水量增大扩散能力增强;高于50g.kg-1时,扩散能力则随含水量增大而减弱。同一扩散柱中,随着扩散距离增加,挥发苯的有效扩散系数增大,这可能与其蒸汽分压降低有关。Effective diffusion coefficient of VOCs in porous medium is an important parameter in the process of mass transfer of soil vapor extraction （SVE）. To study effective diffusion coefficient and diffusion law of volatile benzene in media of fine sands different in water content, a soil column diffusion experiment was carried out. Results show that water content affected diffusion of volatile benzene to a certain extent in such a medium as fine sands containing little adsorptive clay mineral. The diffusion rate was the highest when water content in the medium was 50 g . kg^- 1 ; When the water content was within the range of 0 -50 g .kg^-1, the higher the water content, the higher the diffusion rate. But when it reached beyond 50 g . kg^-1 , the higher the water content, the lower the diffusion rate. Moreover, in the same column, the effectire diffusion coefficient increased along with the distance, which was possibly attributed to a decreasing fractional vapor pressure of volatile benzene.

关 键 词：挥发苯 有效扩散系数 含水量 扩散 

分 类 号：X131.3[环境科学与工程—环境科学] X53