混合捕收剂在锂云母表面吸附行为的分子动力学模拟研究

采用Materials Studio中Forcite模块,对十二胺和油酸钠两种捕收剂分子在锂云母表面的吸附过程进行了分子动力学模拟研究,分析了水分子在吸附前后相应的排布变化。吸附形貌的结果表明,十二胺与油酸钠用量在2∶1时吸附效果最好。通过对捕收剂头基以及碳原子分布函数的分析,其协同作用的机理可能是十二胺首先在锂云母表面进行有效吸附,油酸钠"间接"地通过头基间的静电吸引或是碳链之间的疏水作用,从而增加表面碳链密度和高度并使得吸附层更加稳定。表面水分子自扩散系数的分析也显示,吸附了单层DDA和混合捕收剂的自扩散系数相较纯云母表面的值分别下降了20%和25%左右,表明混合捕收剂的吸附使得锂云母表面更加疏水,从而有利于浮选的进行。

Molecular Dynamics Simulation Study on Adsorption Behavior of Mixed Collector on Lithium Mica Surface

Molecular dynamics simulations of adsorption of mixed DDA and NaOle collectors on lepidolite surface as well as the arrangement of water molecules are investigated by Forcite module in Materials Studio. The results of adsorption configurations show the best DDA/NaOle ratio is 2:1. Distributions of head groups of collectors and C atoms density profiles reveal that DDA prior adsorbs on the lepidolite. And NaOle co-adsorb on the surface by electrical static attraction between opposite-charged head groups or the interaction between the hydrophobic chains, leading to a higher and more stable adsorption layer. The analysis of the self-diffusion coefficient of surface water molecules also showed that the self-diffusion coefficient of the single-layer DDA and the mixed collector was reduced by 20% and 25%, respectively, compared with the pure mica surface. All of the above results indicate that the adsorption of the mixed collector makes the surface of the lithium mica more hydrophobic, which is beneficial to the flotation.