Trefalt Gregor, Ruiz-Cabello F Javier Montes, Borkovec Michal
Department of Inorganic and Analytical Chemistry, University of Geneva , Sciences II, 30 Quai Ernest-Ansermet, 1205 Geneva, Switzerland.
J Phys Chem B. 2014 Jun 12;118(23):6346-55. doi: 10.1021/jp503564p. Epub 2014 Jun 2.
Force profiles as well as aggregation and deposition rates are studied for asymmetrically charged particles and surfaces in aqueous electrolytes theoretically. Interactions are calculated within the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, whereby the electrostatic part is modeled at Poisson-Boltzmann (PB) level. Unequally charged surfaces are examined, from the symmetric system, where both surfaces are equally charged, to fully asymmetric systems, where the surfaces are oppositely charged. Charged-neutral systems, where one surface is charged and the other is neutral, emerge as an essential scenario. In this case, the choice of boundary conditions used for solving the PB equation is crucial, whereby constant charge and constant potential boundary conditions lead to either fully repulsive or fully attractive forces. Consequently, charge regulation has a major influence on particle aggregation and deposition rates too. In the charge-neutral case, substantial shifts in the critical coagulation concentration (CCC) are observed when the regulation properties are changed. In the presence of multivalent ions, these systems behave similarly to the symmetrically charged ones. The CCC decreases with the square of the valence in weakly charged systems, while unrealistically high charge densities are needed to recover the classical Schulze-Hardy limit, which predicts a sixth power dependence on valence.
本文从理论上研究了水性电解质中不对称带电粒子与表面的力分布以及聚集和沉积速率。相互作用是在德亚金、朗道、韦弗伊和奥弗贝克（DLVO）理论框架内计算的，其中静电部分是在泊松 - 玻尔兹曼（PB）水平上建模的。研究了从对称系统（两个表面带等量电荷）到完全不对称系统（表面带相反电荷）的不等电荷表面。带电 - 中性系统（一个表面带电而另一个表面中性）是一种重要情况。在这种情况下，用于求解PB方程的边界条件的选择至关重要，恒定电荷和恒定电位边界条件分别导致完全排斥或完全吸引的力。因此，电荷调节对粒子聚集和沉积速率也有重大影响。在电荷中性情况下，当调节特性改变时，临界凝聚浓度（CCC）会发生显著变化。在多价离子存在的情况下，这些系统的行为与对称带电系统类似。在弱带电系统中，CCC随价数的平方降低，而需要不切实际的高电荷密度才能恢复经典的舒尔茨 - 哈迪极限，该极限预测CCC对价数有六次方的依赖性。
