Abstract All-atom molecular simulations and chemical quantum calculations were used to understand the effect of the environment on the surface adsorption of corrosion inhibitor (CI) molecules. Three CIs abbreviated: TEPA, iTEPA and HC-iTEPA studied in this work, were selected to systematically investigate the influence of the alkyl tail, N-pendant group, imidazoline and benzene rings, on the CIs adsorption behavior. A relationship is provided between their structural properties and their surface protectiveness ability in different environments. Chemical quantum calculations revealed the electron distribution in inhibitors structures, indicating their ability to accept/donate charges from the Fe atoms in vacuum and in water solvation. The quantum molecular parameters in water solvation anticipated higher electron transfer ability of iTEPA in aqueous conditions compared to TEPA and iTEPA, thus, leading to stronger adsorption on iron surface, corroborated by the molecular dynamics (MD) classical simulations. MD simulations showed that nearly 53%, 39%, 59% reduction in adsorption energies was detected for single inhibitor molecule of TEPA, iTEPA, and HC-iTEPA shifting from water to CO2-saline media, respectively. The formation of water double adsorption layer contributed to decreasing the CIs adsorption energies by the larger surface separation distances spotted in the density profiles. Nevertheless, the multi-inhibitors study revealed strong adsorption of TEPA and iTEPA on the iron surface, while HC-iTEPA neglected cooperative adsorption and aggregated as a spherical-like micelle with lower surface coverage propensity. Radial distribution functions g(r) explored the preferential interactions of inhibitor-H2O and inhibitor-CO2 that guided the CIs adsorption conformation. Self-diffusivity coefficients of competing adsorbates with the three CIs were found to be one to two orders of magnitude lower near the interface than in the bulk.

中文翻译：

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了解三种缓蚀剂的结构特性与其在不同环境下的表面保护能力之间的关系

摘要 利用全原子分子模拟和化学量子计算来了解环境对缓蚀剂 (CI) 分子表面吸附的影响。选择三个 CI 缩写：TEPA、iTEPA 和 HC-iTEPA 在这项工作中研究，系统地研究烷基尾、N-侧基、咪唑啉和苯环对 CI 吸附行为的影响。提供了它们的结构特性与其在不同环境中的表面保护能力之间的关系。化学量子计算揭示了抑制剂结构中的电子分布，表明它们在真空和水溶剂化中从 Fe 原子接受/提供电荷的能力。与 TEPA 和 iTEPA 相比，水溶剂化中的量子分子参数预期 iTEPA 在水性条件下具有更高的电子转移能力，从而导致铁表面更强的吸附，分子动力学 (MD) 经典模拟证实了这一点。MD 模拟表明，对于 TEPA、iTEPA 和 HC-iTEPA 的单个抑制剂分子从水转移到 CO2-盐水介质，分别检测到吸附能降低了近 53%、39%、59%。水双吸附层的形成有助于通过密度分布中发现的较大表面分离距离降低 CIs 吸附能。尽管如此，多抑制剂研究表明铁表面上 TEPA 和 iTEPA 有很强的吸附作用，而HC-iTEPA忽略了协同吸附并聚集成具有较低表面覆盖倾向的球形胶束。径向分布函数 g(r) 探索了抑制剂-H2O 和抑制剂-CO2 的优先相互作用，这些相互作用引导了 CIs 吸附构象。发现具有三个 CI 的竞争吸附物的自扩散系数在界面附近比在本体中低一到两个数量级。