月桂基咪唑啉对Q235钢的缓蚀吸附作用

摘要

采用失重法和电化学方法研究了月桂基咪唑啉(IM-11)、1-氨乙基-2-月桂基咪唑啉(AIM-11)和1-羟乙基-2-月桂基咪唑啉(HIM-11)三种化合物在CO2饱和的3%NaCl溶液中对Q235钢的缓蚀性能,探讨了其在Q235钢表面的吸附行为.结果显示,3种化合物均具有较好的抗CO2腐蚀的缓蚀性能,缓蚀性能的大小顺序为HIM-11>AIM-11>IM-11.3种缓蚀剂在Q235钢表面上的吸附过程为自发、放热过程,吸附行为服从Langmuir吸附等温式,属于以化学吸附为主的混合吸附.通过量子化学密度泛函理论(DFT)研究了缓蚀剂的分子结构与缓蚀效率之间的关系,建立了定量构效关系(QSAR)模型.缓蚀剂吸附过程的分子动力学模拟结果显示,与金属界面发生吸附时,3种缓蚀剂分子上的咪唑环和亲水支链上的极性官能团优先吸附,分子在Fe表面的吸附稳定性按HIM-11、AIM-11、IM-11的顺序逐渐减弱.理论计算与实验结果相一致.%The corrosion inhibition and adsorption behavior of lauryl-imidazoline (IM-11), 1-aminoethyl-2-lauryl-imidazoline (AIM-11) and 1-hydroxyethyl-2-lauryl-imidazoline (HIM-11) were investigated as corrosion inhibitors for Q235 steel corrosion in 3％ NaC1 solution saturated with CO2 by mass loss and electrochemical polarization curves. The results indicated that the three inhibitors all showed excellent corrosion inhibition performance in CO2 corrosion environment. The inhibition efficiency order of the three inhibitors was HIM-11 ＞ AIM-11 ＞ IM-11. The adsorption was spontaneous and exothermic and followed Langmuir isotherm. It belonged to mix-type adsorption mainly dominated by chemisorption. The relationship between molecular structure and inhibition efficiency was investigated by density functional theory (DFT) of quantum chemical calculations, and the quantitative structure-activity relationship (QSAR) model was established. The adsorption behavior of inhibitor molecules on Fe (001) surface was simulated by the molecular dynamics method. The results showed that the ring imidazole and heteroatoms of the polar group on the hydrophilic chain preferentially adsorbed when the inhibitors reacted with metal surface, and the adsorption stability weakened gradually in the order of HIM-11, AIM-11, IM-11. The theoretical calculation accorded well with experimental results.