VOC accumulation and pore filling in unsaturated porous media

被引:15
作者
Corley, TL
Farrell, J
Hong, B
Conklin, MH
机构
[1] UNIV ARIZONA,DEPT HYDROL & WATER RESOURCES,TUCSON,AZ 85721
[2] UNIV ARIZONA,DEPT CHEM & ENVIRONM ENGN,TUCSON,AZ 85721
关键词
D O I
10.1021/es950644k
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
A series of unsaturated column experiments was conducted to study different grain-scale accumulation mechanisms affecting total uptake of volatile organic compounds (VOCs) onto a model solid and subsequent removal of VOCs from the porous media. Experimental variables included VOC (benzene, methylbenzene, 1,4-dimethylbenzene, and 1,3,5-trimethylbenzene), moisture content (primarily water-unsaturated conditions), and influent VOC concentration. Calculations of the mass distributions of benzene indicated that it was primarily in the aqueous and air phases with a small fraction at the air-water interface. Similar calculations for the other VOCs indicated that greater than 50% of the accumulated mass of these VOCs was located within intraparticle pores and on the substrate surface. Analysis of the sorption data in terms of a pore-filling model support the hypothesis that a capillary phase separation (CPS) process occurred within the pores and produced a neat, separate VOC phase. We suggest that CPS will become more critical in materials with small mesopores or micropores, and that it is partly responsible for the existence of a resistant fraction of VOCs present within water-filled intraparticle pores.
引用
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页码:2884 / 2891
页数:8
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