Determining Parameters and Mechanisms of Colloid Retention and Release in Porous Media.
Determining Parameters and Mechanisms of Colloid Retention and Release in Porous Media.
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DOI：
10.1021/acs.langmuir.5b03080
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发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
S. Bradford;S. Torkzaban
中科院分区：
文献类型：
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作者：
S. Bradford;S. Torkzaban
提出了一个建模框架，以确定胶体（微生物、粘土和纳米颗粒）在多孔介质表面的保留和释放的基本参数和控制机制，这些介质具有广泛的纳米级化学非均质性、纳米到微尺度的粗糙度和孔隙水速度。在非均质固体表面上确定了静电影响区内的初级和/或次级最小相互作用。随后采用麦克斯韦动能模型来确定每个最小值的固定和扩散释放胶体的概率。此外，还平衡了施加的水动力和抵抗胶粘剂扭矩，以确定在存在空间可变水流和微观粗糙度的情况下固定和水动力释放的位置。保留位置必须同时满足固定的能量和扭矩平衡条件，而释放可能由于扩散或流体动力学而发生。将多孔介质基本表面积上的能量和扭矩平衡结果相加，可以估算出胶体的保留和释放参数，这些参数对预测环境命运至关重要，包括粘着和释放效率以及固相上保留的胶体的最大浓度。即使在平均化学条件不利的情况下，纳米尺度的粗糙度和化学异质性也会产生局部的初级最小相互作用，控制长期保留。在低离子强度和高流体动力条件下，微观粗糙度对胶体的保留起主导作用，特别是对于较大的胶体。
A modeling framework is presented to determine fundamental parameters and controlling mechanisms of colloid (microbes, clays, and nanoparticles) retention and release on surfaces of porous media that exhibit wide distributions of nanoscale chemical heterogeneity, nano- to microscale roughness, and pore water velocity. Primary and/or secondary minimum interactions in the zone of electrostatic influence were determined over the heterogeneous solid surface. The Maxwellian kinetic energy model was subsequently employed to determine the probability of immobilization and diffusive release of colloids from each of these minima. In addition, a balance of applied hydrodynamic and resisting adhesive torques was conducted to determine locations of immobilization and hydrodynamic release in the presence of spatially variable water flow and microscopic roughness. Locations for retention had to satisfy both energy and torque balance conditions for immobilization, whereas release could occur either due to diffusion or hydrodynamics. Summation of energy and torque balance results over the elementary surface area of the porous medium provided estimates for colloid retention and release parameters that are critical to predicting environmental fate, including the sticking and release efficiencies and the maximum concentration of retained colloids on the solid phase. Nanoscale roughness and chemical heterogeneity produced localized primary minimum interactions that controlled long-term retention, even when mean chemical conditions were unfavorable. Microscopic roughness played a dominant role in colloid retention under low ionic strength and high hydrodynamic conditions, especially for larger colloids.