K_2L-SAMs对碳钢在饱和CO_2油田水中的缓蚀行为与量子化学研究

Corrosion inhibition and quantum chemistry studies of K_2L-SAMs for carbon steel in CO_2-saturated oilfield water

利用邻氧乙酸苯甲醛缩对氨基苯磺酸钾盐席夫碱(K2L)缓蚀剂在20#碳钢表面制备自组装单分子膜(SAMs),并通过电化学方法研究缓蚀剂自组装膜的最佳组装时间;采用电化学测试技术和表面分析技术研究K2L-SAMs对碳钢在饱和CO2油田水介质中的缓蚀行为;采用密度泛函理论分析缓蚀剂分子的前线轨道、Mulliken电荷和分子静电势。结果表明:缓蚀剂在碳钢表面自组装3 h后,可以形成稳定、致密的缓蚀膜;在碳钢表面形成的K2L-SAMs能有效抑制碳钢的阴极还原过程,最高缓蚀效率达87.55%;K2L的吸附行为符合Langmuir吸附等温式,吸附机理为典型的化学吸附。量子化学计算结果表明:羧基是K2L分子的主要吸附活性区域,能与碳钢表面铁原子作用形成稳定的配位键。

The self-assembled monolayers（SAMs） were prepared on the surface of 20# carbon steel by using 2-[（4-sulfonic potassium phenyl imino） methylene] phenoxyacetic acid potassium salt（K2L） as corrosion inhibitor,and the best self-assembled time of the SAMs on the surface of carbon steel was investigated by electrochemical methods. The inhibition behavior of the K2L-SAMs with the carbon steel in CO2-saturated oilfield water was studied by electrochemical test technology and surface analysis technique.The frontier orbitals,Mulliken charges and molecular electrostatic potential of the corrosion inhibitor were analyzed by the density functional theory.The results show that the corrosion inhibitor can form stable and compact corrosion SAM on the surface of carbon steel after 3h immersion in the aqueous solution of the corrosion inhibitor.The processes of cathodic reduction are restrained by the steady K2L-SAMs on the surface of carbon steel,and the highest inhibition efficiency is 87.55%.The adsorption behavior of the K2L-SAMs on the carbon steel surface follows the Langmuir adsorption isotherm,and the adsorption mechanism is typically chemical adsorption.Quantum chemistry calculation results show that carboxyl is mainly active area of the adsorption of K2L molecule,which can interact with Fe atoms on the carbon steel surface by the stable coordination bonds.