Ong Gary M C, Gallegos Alejandro, Wu Jianzhong
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States.
Langmuir. 2020 Oct 13;36(40):11918-11928. doi: 10.1021/acs.langmuir.0c02000. Epub 2020 Sep 28.
Colloidal particles are mostly charged in an aqueous solution because of the protonation or deprotonation of ionizable groups on the surface. The surface charge density reflects a complex interplay of ion distributions within the electric double layer and the surface reaction equilibrium. In this work, we present a coarse-grained model to describe the charge regulation of various colloidal systems by an explicit consideration of the inhomogeneous ion distributions and surface reactions. With the primitive model for aqueous solutions and equilibrium constants for surface reactions as the inputs, the theoretical model is able to make quantitative predictions of the surface-charge densities and zeta potentials for diverse colloidal particles over a wide range of pH and ionic conditions. By accounting for the ionic size effects and electrostatic correlations, our model is applicable to systems with multivalent ions that exhibit charge inversion and provides a faithful description of the interfacial properties without evoking the empirical Stern capacitance or specific ion adsorptions.
在水溶液中，由于表面可电离基团的质子化或去质子化作用，胶体颗粒大多带有电荷。表面电荷密度反映了双电层内离子分布与表面反应平衡之间复杂的相互作用。在这项工作中，我们提出了一个粗粒度模型，通过明确考虑不均匀的离子分布和表面反应来描述各种胶体系统的电荷调节。以水溶液的原始模型和表面反应的平衡常数作为输入，该理论模型能够在很宽的pH值和离子条件范围内，对各种胶体颗粒的表面电荷密度和zeta电位进行定量预测。通过考虑离子尺寸效应和静电相关性，我们的模型适用于具有电荷反转现象的多价离子体系，并且在不引入经验性斯特恩电容或特定离子吸附的情况下，能够如实地描述界面性质。
