噻二唑衍生物分子结构与其缓蚀性能的关系  

Corrosion inhibition and olecular structure of thiadiazole derivatives in sulfur-ethanol system

作　　者：刘琳[1] 潘晓娜[1] 张强[1,2] 钱建华[1] 

机构地区：[1]渤海大学功能化合物的合成及应用辽宁省重点实验室,辽宁锦州121000 [2]中国科学院大连物理化学研究所,辽宁大连116023

出　　处：《化工学报》2014年第10期4039-4048,共10页CIESC Journal

基　　金：国家自然科学基金项目(21176030);辽宁省高等学校优秀人才支持计划项目(LR2011033)~~

摘　　要：利用交流阻、Tafel极化曲线和原子力显微镜(AFM),研究2-氨基-1,3,4-噻二唑(ATD)、5-甲基-2-氨基-1,3,4-噻二唑(MATD)、5-苯基-2-氨基-1,3,4-噻二唑(PATD)和2,5-二苯基-1,3,4-噻二唑(DPTD)4种具有不同取代基的噻二唑衍生物在50 mg·L-1硫溶液中对金属银的缓蚀性能。实验结果表明:缓蚀剂成功地吸附到了金属表面,金属腐蚀受到明显的抑制,且4种缓蚀剂的缓蚀效率的大小顺序是:MATD>PATD>ATD>DPTD。位于噻二唑环2,5位置上非极性和极性基团结构的变化,极性基团均对缓蚀剂的缓蚀性能有较大影响。因极性基团更容易吸附到金属表面,所以当噻二唑环上存在极性基团时,其抗腐蚀性能明显增强;当环上存在非极性基团时,与芳基相比,非极性基团为烷基时,其缓蚀性能更好,原因可能是由于芳基的体积较大,在吸附过程中受到的阻力较大。通过动力学分析可知:4种缓蚀剂在金属表面的吸附遵循Langmuir吸附等温方程,吸附类型属于化学吸附为主的混合吸附。通过分子动力学模拟,进一步研究了4种缓蚀剂的抗腐蚀机理,结果表明缓蚀剂与金属界面发生吸附时,4种缓蚀剂的噻二唑环和环上亲水支链中的极性基团优先吸附到金属银表面,理论计算和实验结果一致。The inhibition performances of thiadiazole derivatives, namely, 2-amino-1,3,4-thiadiazole （ATD）, 5-metheyl-2-amino-1,3,4-thiadiazole （MATD）, 5-phenyl-2-amino-1,3,4-thiadiazole （PATD）, and 2,5-diphenyl- 1,3,4-thiadiazole （DPTD）, on silver strip corrosion in 50 mg·L-1 sulfur solution was studied using electrochemical impedance spectroscopy （EIS）, Tafel polarization techniques and atom force microscopy （AFM）. These measurements showed that the addition inhibited silver strip corrosion, and the inhibitor formed a protected film on the silver strip surface. The inhibition efficiency decreased in the order of MATD ＆gt; PATD ＆gt; ATD ＆gt; DPTD. The substitutes, which occupied 1 or 2 sites on the central five membered ring and had polar groups and non-polar groups properties and some active functional groups showed an important effect on the inhibition performance of thiadiazole derivatives. Compounds showed the best inhibitive efficiency when thiadiazole derivatives had the polar groups and the best inhibitive efficiency when non-polar groups were alkyl groups, because steric exclusion of aromatic groups decreased the adsorption. Kinetics analysis indicated that adsorption of the four inhibitors onto silver surface followed Langmuir adsorption isotherm. The adsorption belonged to mix-type adsorption mainly dominated by chemisorption. The inhibition mechanism of four corrosion inhibitors against sulfur corrosions was theoretically studied using molecular dynamics simulations. The results indicated that the ring thiadiazole and heteroatom of the polar group on the hydrophilic chain were preferentially adsorbed when the inhibitors reacted with metal surface, and the theoretical calculation accorded well with experimental results.

关 键 词：噻二唑衍生物 缓蚀 动力学 吸附 腐蚀 分子动力学模拟 

分 类 号：TG174[金属学及工艺—金属表面处理]