水相环境中十二胺在石英及磁铁矿表面吸附的分子动力学模拟

摘要

采用分子动力学模拟方法,研究周期性水环境下十二胺在石英及磁铁矿界面上的吸附过程.考虑到十二胺的水解电离平衡以及矿物表面荷电机理,建立弱酸、中性以及强碱性3种条件下十二胺与石英及磁铁矿的吸附模型.采用微量热仪测量十二胺在石英及磁铁矿表面吸附过程中的吸附热.模拟结果表明:中性环境有利于十二胺在矿物表面的吸附;弱酸性条件下十二胺不能吸附于磁铁矿表面;强碱性环境下十二胺与石英及磁铁矿的相互作用很弱.十二胺与石英作用的吸附焓大于十二胺与磁铁矿的,十二胺更易于吸附在石英表面,且十二胺在矿物表面的吸附为物理吸附.分子动力学模拟与吸附热试验从分子力学及热力学层面上揭示了浮选过程中十二胺对石英及磁铁矿选择性的差异的原因.%The adsorption process of dodecylamine (DDA) on quartz and magnetite surfaces at a molecular level was studied by molecular dynamics (MD) simulations method. In the consideration of hydrolysis ionization equilibrium and surface charge mechanism of DDA, a model close to the realistic flotation system was established to simulate the adsorption behavior under the weak acid, neutral and strong alkali conditions. The adsorption heat in the adsorption process of DDA on quartz and magnetite surface was measured by micro calorimeter. The results indicate that the optimum condition for DDA adsorption on mineral surface is at neutral environment; it is difficult for DDA adsorption on magnetite at weak acid environment; and the interaction of DDA and mineral is weak under strong alkali condition. The interaction energy of DDA and quartz is higher than that of DDA and magnetite. DDA is preferred to adsorb on the surface of quartz, and the adsorption process is physical adsorption. The selectivity phenomenon in molecular mechanics and thermodynamics level was explained by MD simulation and microcalorimetry measurements experiment.