Parsons Drew F, Salis Andrea
School of Engineering and Information Technology, Murdoch University, 90 South St, Murdoch, WA 6150, Australia.
Department of Chemical and Geological Sciences, University of Cagliari-CSGI and CNBS, Cittadella Universitaria, S.S. 554 bivio Sestu, 09042 Monserrato (CA), Italy.
J Chem Phys. 2015 Apr 7;142(13):134707. doi: 10.1063/1.4916519.
The relationship between surface charge and surface potential at the solid-liquid interface is often determined by a charge regulation process, the chemisorption of a potential determining ion such as H(+). A subtle ion-specific effect can be observed when other ions compete with the primary potential determining ion to bind to a surface site. Site competition may involve alternative ions competing for a first binding site, e.g., metals ions competing with H(+) to bind to a negatively charged oxide or carboxyl site. Second-binding sites with site competition may also be found, including amphoteric OH2 (+) sites, or anion binding to amine groups. In this work, a general theoretical model is developed to describe the competitive adsorption of ions at surface sites. Applied to the calculation of forces, the theory predicts a 20% increase in repulsion between titania surfaces in 1 mM NaCl, and a 25% reduction in repulsion between silica surfaces in 0.1M NaCl compared to calculations neglecting ion site competition.
固液界面处的表面电荷与表面电势之间的关系通常由电荷调节过程决定，即诸如H(+)等电势决定离子的化学吸附。当其他离子与主要电势决定离子竞争结合表面位点时，可以观察到微妙的离子特异性效应。位点竞争可能涉及替代离子竞争第一结合位点，例如金属离子与H(+)竞争结合带负电荷的氧化物或羧基位点。也可能发现存在位点竞争的第二结合位点，包括两性OH2(+)位点，或阴离子与胺基的结合。在这项工作中，开发了一个通用理论模型来描述离子在表面位点的竞争吸附。应用于力的计算时，与忽略离子位点竞争的计算相比，该理论预测在1 mM NaCl中二氧化钛表面之间的排斥力增加20%，在0.1 M NaCl中二氧化硅表面之间的排斥力降低25%。
