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	On colloid retention in saturated porous media in the presence of energy barriers: The failure of ��, and opportunities to predict ��
	Johnson, William P. ; Tong, Meiping ; Li, Xiqing
	2007
英文摘要	This contribution reviews recent findings that illuminate the processes governing colloid retention in porous media under environmentally relevant conditions. In the environment, colloids act as conveyors of contaminants, or even as contaminants themselves; however, despite decades of research, we are unable to accurately predict the retention of colloids in granular aquifer media under environmental conditions, where repulsion exists between colloids and surfaces. This failure cannot be blamed solely on the complexities of the subsurface, since colloid filtration theory (CFT) works well in the absence of colloid-collector repulsion despite its idealization of porous media as consisting of spherical grains completely surrounded by fluid envelopes. Rather, the failure of CFT stems from failure to incorporate the correct mechanisms of retention when repulsion exists. Recent observations implicate wedging in grain-to-grain contacts and retention in secondary energy minima as dominant mechanisms of colloid retention in the presence of an energy barrier. Mechanistic simulations in unit cells containing grain-to-grain contacts corroborate these mechanisms of colloid retention. The resulting concept for colloid retention in the presence of an energy barrier involves translation of colloids across the collector surfaces until they become wedged within grain-to-grain contacts, or are retained via secondary energy minima (without attachment) in zones where the balance of fluid drag, diffusion, gravitational, and colloid-collector interaction forces allow retention. The above findings highlight the pore domain geometry as a dominant governor of colloid retention in so far as the geometry gives rise to grain-to-grain contacts and zones of relatively low fluid drag. Copyright 2007 by the American Geophysical Union.; EI; 12; 43
语种	英语
DOI标识	10.1029/2006WR005770
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/461610]
专题	城市与环境学院 环境科学与工程学院
推荐引用方式 GB/T 7714	Johnson, William P.,Tong, Meiping,Li, Xiqing. On colloid retention in saturated porous media in the presence of energy barriers: The failure of ��, and opportunities to predict ��. 2007-01-01.

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