[BMIM]HSO_4离子液体腐蚀性的实验与分子模拟

Experimental and molecular simulation of corrosion of steel in [BMIM]HSO_4 ionic liquid

基于失重法和分子模拟方法,研究了1-丁基-3-甲基咪唑硫酸氢盐([BMIM]HSO_4)的腐蚀性和离子液体分子与金属表面的相互作用。实验结果表明[BMIM]HSO_4对304不锈钢具有腐蚀性,且在水溶液中腐蚀性显著增强。基于量子化学方法计算了[BMIM]HSO_4分子的HOMO和LUMO分布、Fukui指数及分子内部特征参数,计算结果表明[BMIM]HSO_4在Fe金属表面吸附的位置主要集中在阴离子硫酸氢根和阳离子咪唑环上,可分别形成配位键和反馈键,在水溶液中[BMIM]HSO_4分子与金属表面的相互作用变弱。分子动力学模拟揭示了在不同的环境中[BMIM]HSO_4分子在Fe金属表面的吸附过程和吸附能。量子化学计算和分子动力学模拟结果一致,从理论上解释了在水溶液中[BMIM]HSO_4腐蚀性增强的原因。

The corrosion behaviors of steel in [BMIM]HSO_4 ionic liquid（IL） were investigated by immersion tests and molecular simulation. The corrosion rates of stainless steel 304 in IL were determined by mass loss measurement. The result indicates that the presence of H2 O greatly enhances the corrosivity of IL. The distribution of HOMO and LUMO, Fukui indices and quantum chemical parameters on IL molecule were calculated. The results show that the imidazolium ring and hydrogen sulfate play the most important role in the interaction between IL and metal surface. The quantum chemical parameters of IL in aqueous solution significantly change. The chemical adsorption ability of IL becomes weak. The adsorption process and adsorption energy of IL on steel surface in water-free and aqueous environments were investigated by molecular dynamics simulation. The molecular simulation results are consistent well with corrosion results, which can provide a better understanding of the interaction between ionic liquid and metal surface at the molecular level.