Coupling effects during steady-state solute diffusion through a semipermeable clay membrane
Coupling effects during steady-state solute diffusion through a semipermeable clay membrane
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DOI：
10.1021/es011130q
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发表时间：
2002-03-15
影响因子：
11.4
通讯作者：
Shackelford, CD
中科院分区：
文献类型：
--
作者：
Malusis, MA;Shackelford, CD
关于氯化钾(M)在膨润土基土工合成粘土衬里(GCL)中的稳态扩散，评估了两种独立的耦合效应，该衬里具有半透膜的作用。这两种耦合效应都与测得的化学渗透效率系数omega相关，对于GCL，其范围从0.14到0.63。第一个耦合效应是一种显式的(理论上)盐筛选效应，表示为耦合的有效盐扩散系数D-omega*，由于观察到的膜行为，它低于真实的(非耦合的)有效盐扩散系数D-S*。然而，根据测量的氯浓度，D-omega*和D-S*之间的最大差异相对较小(即=10%)，并且差异随着w的减小而减小(即D-omega*-->；D-S*为omega->；0)。第二个耦合效应是隐性的(经验性的)，其特征是测量与浓度相关的有效盐扩散系数，当w从0.14增加到0.63时，D-S*的降幅类似于300%。由隐式耦合引起的D-S*的降低归因于用限制性曲折因子描述的溶质排斥。
Two separate coupling effects are evaluated with respect to steady-state potassium chloride (M) diffusion through a bentonite-based geosynthetic clay liner (GCL) that behaves as a semipermeable membrane. Both of the coupling effects are correlated with measured chemico-osmotic efficiency coefficients, omega, that range from 0.14 to 0.63 for the GCL. The first coupling effect is an explicit (theoretical) salt-sieving effect expressed as a coupled effective salt diffusion coefficient, D-omega*, that is lower than the true (uncoupled) effective salt diffusion coefficient, D-s*, because of the observed membrane behavior. However, the maximum difference between D-omega* and D-s* based on measured chloride concentrations is relatively small (i.e., = 10%), and the difference decreases with decreasing w (i.e., D-omega* --> D-s* as omega --> 0). The second coupling effect is implicit (empirical) and is characterized by the measurement of concentration-dependent effective salt diffusion coefficients that results in an similar to300% decrease in D-s* as w increases from 0.14 to 0.63. The decrease in D-s* resulting from implicit coupling is attributed to solute exclusion described in terms of a restrictive tortuosity factor.