4-氨基苯甲酸席夫碱自组装缓蚀膜对20#钢在饱和CO2油田水中的缓蚀性能

利用邻氧乙酸苯甲醛缩4-氨基苯甲酸钾盐席夫碱(K₂L1)缓蚀剂在20#碳钢表面制备了自组装单分子膜(SAMs),通过电化学方法研究了缓蚀剂的合成条件、自组装时间等因素对成膜的影响,结果表明,合成中KOH与邻氧乙酸苯甲醛按2:1摩尔比进行反应得到的K₂L1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。缓蚀性能的研究表明,碳钢表面K₂L1-SAMS抑制了碳钢的阴极还原过程,改变了电极表面双电层结构,具有良好的缓蚀效果(最高缓蚀效率可达95%以上),交流阻抗和极化曲线得到的结论是一致的。同时研究表明K₂L1的吸附行为符合Langmuir吸附等温式,吸附机理是典型的化学吸附。量子化学计算结果表明,K₂L1分子具有多个吸附活性中心,这些活性原子的前线轨道能与碳钢表面铁原子的前线轨道相互作用,因而使得K₂L1分子在碳钢表面形成吸附膜,阻止了碳钢在饱和CO₂油田水介质中的溶解。X射线光电子能谱(XPS)分析表明,K₂L1通过配位键在碳钢表面形成了稳定的缓蚀膜。

Corrosion inhibition behavior of self-assembled monolayer of 4-aminobenzoic acid Schiff bases for 20# carbon steel in CO2-saturated oilfield water

By using 2-(4-carboxyl)phenyl iminomethylene]phenoxyacetic acid(K₂L1)as corrosion inhibitor,the self-assembled monolayers(SAMs)were prepared on the surface of 20^# carbon steel,and the influence factors of the inhibition film,i.e.,synthesis conditions of corrosion inhibitor and best self-assembly time were investigated by electrochemical method.The molar ratio of KOH to o-formylphenoxyacetic acid was 2:1 for the synthesis of the K₂L1 inhibitor,and a fairly dense stable inhibition film of SAM could be formed on carbon steel surface after 3 h immersion.The research of corrosion inhibition indicated that K₂L1 SAMs changed the structure of the double-electric layer on carbon steel electrode surface.In addition,SAMs restrained the process of cathodic reduction and had good anticorrosion effect with the highest inhibition efficiency up to 95%,which was in good agreement with the results obtained by EIS and polarization curve methods.Electrochemical measurements indicated that the corrosion resistance for carbon steel electrode was enhanced by the K₂L1-SAMs. Adsorption behavior of the K₂L1-SAMs followed the Langmuir's adsorption isotherm,and the adsorption mechanism was typical chemisorption.Quantum chemistry calculation result showed that K₂L1 molecule had planar structure with a number of active centers,and their frontier orbitals could interact with those Fe atom on the surface of carbon steel.Thus they might form an adsorption barrier film on the carbon steel surface to decrease the corrosion rate of carbon steel.X-ray photoelectron spectroscopy showed that the stable inhibition film by K₂L1 on carbon steel surface was due to the formation of coordination bond.