Simulation of Colloid Transport and Retention Using a Pore‐Network Model With Roughness and Chemical Heterogeneity on Pore Surfaces
Simulation of Colloid Transport and Retention Using a Pore‐Network Model With Roughness and Chemical Heterogeneity on Pore Surfaces
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DOI：
10.1029/2020wr028571
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发表时间：
2021-02
影响因子：
5.4
通讯作者：
Dantong Lin;Liming Hu;S. Bradford;Xinghao Zhang;Irene M. C. Lo
中科院分区：
文献类型：
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作者：
Dantong Lin;Liming Hu;S. Bradford;Xinghao Zhang;Irene M. C. Lo
胶体在多孔介质中的迁移和滞留是自然界和工业生产中普遍存在的现象。然而，许多问题仍然是如何获得胶体的传输和保留参数。以往的工作通常假设在介质中的物理化学条件下，传输参数是恒定的。在这项研究中，采用孔隙网络建模将胶体的运输和保留从孔隙尺度提升到宏观尺度。通过数值模拟和概率分析，获得了各孔喉的孔隙尺度运移参数，包括收集效率（η）、粘附效率（α）和有利于胶体附着的固-水界面分数（Sf）。讨论了粗糙度和电荷不均匀性对孔隙尺度参数分布的影响。分析了不同粗糙度和电荷不均匀性条件下的穿透曲线和保留曲线。结果表明，孔隙尺度参数η、α和Sf在多孔介质中具有不同的分布，用单值有效参数可能无法准确描述。η值随速度减小，在低速条件下呈现宽分布。参数α随胶体粒径和孔隙水流速的增大而减小，随电荷不均匀性分数的增大而增大。纳米级粗糙度以非单调的方式改变α，但对于较低的粗糙度分数和zeta电位，α趋于增加。微观粗糙度增加了胶体的α值，否则这些胶体将容易受到流体动力学去除的影响。穿透曲线和保留曲线表明，更小的颗粒发生更多的保留，这反映了阻塞的影响。
Colloid transport and retention in porous media is a common phenomenon in both nature and industry. However, many questions remain on how to obtain colloid transport and retention parameters. Previous work usually assumed constant transport parameters in a medium under a given physicochemical condition. In this study, pore‐network modeling is employed to upscale colloid transport and retention from the pore‐scale to the macro‐scale. The pore‐scale transport parameters including the collection efficiency (η), the sticking efficiency (α), and the fraction of the solid‐water interface that contributes to the colloid attachment (Sf) are obtained using numerical simulation and probability analysis for each pore throat. The influence of roughness and charge heterogeneity on the distribution of pore‐scale parameters is discussed. Breakthrough curves and the retention profiles under different roughness and charge heterogeneity conditions are also analyzed. Results show that pore‐scale parameters η, α, and Sf have various distributions in porous media that may not be accurately described using single‐valued effective parameters. The value of η decreases with velocity and exhibits a wide distribution under low‐velocity conditions. The parameter α tends to decrease with the colloid size and the pore water velocity and increased with the charge heterogeneity fraction. Nanoscale roughness alters α in a non‐monotonic fashion but tends to increase for lower roughness fractions and zeta potential. Microscopic roughness increases values of α for colloids that would otherwise be susceptible to hydrodynamic removal. Breakthrough curves and retention profiles show that more retention occurs for smaller particles, which reflects the influence of blocking.