Pérez C A, Moncho-Jordá A, Hidalgo-Álvarez R, Casanova H
Colloids Group, Institute of Chemistry, University of Antioquia, Medellin, Colombia.
Eur Phys J E Soft Matter. 2012 Aug;35(8):69. doi: 10.1140/epje/i2012-12069-x. Epub 2012 Aug 8.
Brownian dynamics simulations (BDS) of sedimentation and irreversible adsorption of colloidal particles on a planar surface were carried out at bulk particle volume fractions (φ) in the range 0.05 to 0.25. The sedimentation and adsorption of colloidal particles were simulated as a non-sequential process that allows simultaneous settling and adsorption of particles. A kinetic model for the formation of particle monolayers based on the available surface fraction (θ(A)) is proposed to predict simulation results. The simulations show a value of 0.625 for the maximum fractional surface coverage (θ(∞)) and a monolayer structure insensitive to φ. However, the kinetic order of the monolayer formation process has a strong dependence with φ, changing from a value close to a unit, at low φ, to a value around two at high φ. This change in the kinetic reaction order is associated to differences of particle adsorption mechanism on the surface. At low φ values, the monolayer formation is achieved by independent adsorption of single particles and the reaction order is close to 1. At high φ values, the simultaneous adsorption of two particles on the surface leads to an increase of the reaction order to values close to 2.
在体相颗粒体积分数（φ）为0.05至0.25的范围内，对平面上胶体颗粒的沉降和不可逆吸附进行了布朗动力学模拟（BDS）。胶体颗粒的沉降和吸附被模拟为一个非顺序过程，该过程允许颗粒同时沉降和吸附。基于可用表面分数（θ(A)）提出了一个颗粒单层形成的动力学模型，以预测模拟结果。模拟结果显示，最大分数表面覆盖率（θ(∞)）的值为0.625，且单层结构对φ不敏感。然而，单层形成过程的动力学级数与φ有很强的依赖性，在低φ时，从接近1的值变化到高φ时约为2的值。动力学反应级数的这种变化与颗粒在表面的吸附机制差异有关。在低φ值时，单层形成是通过单个颗粒的独立吸附实现的，反应级数接近1。在高φ值时，两个颗粒在表面的同时吸附导致反应级数增加到接近2的值。
