Pore-scale visualization of colloid transport and retention in partly saturated porous media
Pore-scale visualization of colloid transport and retention in partly saturated porous media
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DOI：
10.2113/3.2.444
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发表时间：
2004-05-01
影响因子：
2.8
通讯作者：
Steenhuis, TS
中科院分区：
文献类型：
--
作者：
Crist, JT;McCarthy, JF;Steenhuis, TS
在非饱和多孔介质中，胶体在空气-水界面的吸附被认为是控制胶体保留和动员的一种机制。然而，对胶体附着在AW界面上的实际孔隙尺度观察有限。为了进一步研究这些过程，开发了一种实时孔隙尺度可视化方法。该方法建立在研究指状流的光传输的基础上，结合了高分辨率的光电硬件和公共领域成像软件。亲水性带负电的羧化乳胶微球悬浮液的渗透和排水提供了令人信服的视觉证据，证明胶体在砂状多孔介质中的保留是通过在空气-水-固体界面（空气-水-固体）界面相遇的水薄膜中被捕获而发生的。利用这一修正的胶体被困在AWS界面的理论，我们能够解释亲水性胶体似乎在AWS界面上分配的先前实验证据与最近的研究结果之间的明显差异，这些发现表明这种类型的胶体不会在AWS界面上吸附。
In unsaturated porous media, sorption of colloids at the air-water (AW) interface is accepted as a mechanism for controlling colloid retention and mobilization. However, limited actual pore-scale observations of colloid attachment to the AW interface have been made. To further investigate these processes, a real-time pore-scale visualization method was developed. The method builds on the light transmission for fingered flow studies in packed-sand infiltration chambers and combines it with high-resolution, electro-optical hardware and public domain imaging software. Infiltration and drainage of suspensions of hydrophilic negatively charged carboxylated latex microspheres provides compelling visual evidence that colloid retention in sandy porous media occurs via trapping in the thin film of water where the AW interface and the solid interface meet, the air-water solid (AWS) interface. With this modified theory of trapped colloids at the AWS interface, we are able to explain the apparent discrepancy between previous experimental evidence of hydrophilic colloids seemingly partitioning to the AW interface and more recent findings that suggest this type of colloid does not adsorb at the AW interface.