Tang Huajie, Sun Jianlin, Su Daoxin, Huang Ying, Wu Ping
School of Materials Science and Engineering, University of Science and Technology Beijing Beijing 100083 China
Institute of Fundamental and Interdisciplinary Sciences, Beijing Union University Beijing 100010 China.
RSC Adv. 2021 Jul 16;11(40):24926-24937. doi: 10.1039/d1ra02622d. eCollection 2021 Jul 13.
In the present work, the adsorption mechanism and corrosion inhibition effect of coumarin as a green inhibitor was characterized. Quantum chemical calculation and molecular dynamics simulation of the coumarin molecule were performed to get insight into the adsorption model by assessing the frontier orbital parameters and adsorption configuration. The theoretical calculation disclosed that coumarin exhibited a higher adsorption reactivity in the water phase than that in the gas phase, and the C[double bond, length as m-dash]O structure in coumarin was the most favorable site for adsorption occurring. Coumarin could adsorb spontaneously on an aluminum surface in a parallel manner, where electron donation occurred from the aluminum surface to the inhibitor. Additionally, the experimental investigation determined that coumarin decreased the aluminum dissolution by suppressing both the anodic and cathodic reactions. The optimal coumarin concentration of 0.5 wt% resulted in a maximum inhibition efficiency (89.6%), but coumarin at a higher concentration would lead to the competitive and unstable adsorption of inhibitor molecules, thus decreasing the inhibition effect. Moreover, surface chemical characterization confirmed the formation of Al-coumarin complexes, which was in accordance with the theoretical calculation.
在本工作中，对香豆素作为绿色缓蚀剂的吸附机理和缓蚀效果进行了表征。通过评估前沿轨道参数和吸附构型，对香豆素分子进行了量子化学计算和分子动力学模拟，以深入了解吸附模型。理论计算表明，香豆素在水相中的吸附反应性高于气相，香豆素中的C[双键，长度为m破折号]O结构是发生吸附的最有利位点。香豆素可以以平行方式自发吸附在铝表面，电子从铝表面转移到缓蚀剂。此外，实验研究确定香豆素通过抑制阳极和阴极反应来降低铝的溶解。0.5 wt%的最佳香豆素浓度导致最大缓蚀效率（89.6%），但较高浓度的香豆素会导致缓蚀剂分子的竞争性和不稳定吸附，从而降低缓蚀效果。此外，表面化学表征证实了Al-香豆素配合物的形成，这与理论计算结果一致。
