CIESC Journal ›› 2020, Vol. 71 ›› Issue (5): 2230-2239.DOI: 10.11949/0438-1157.20191372

• Surface and interface engineering • Previous Articles     Next Articles

Corrosion inhibition of ionic liquids on the surface of Q235 steel in methanol/sulfuric acid medium

Tianyu ZHENG(),Lu WANG,Jinyan LIU(),Jia WANG   

  1. School of Chemistry and Chemical Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, China
  • Received:2019-11-12 Revised:2020-01-31 Online:2020-05-05 Published:2020-05-05
  • Contact: Jinyan LIU

离子液体在甲醇/硫酸介质中对Q235钢表面的缓蚀性能

郑天宇(),王璐,刘金彦(),王佳   

  1. 内蒙古科技大学化学与化工学院,内蒙古 包头 014010
  • 通讯作者: 刘金彦
  • 作者简介:郑天宇(1996—),男,硕士研究生,zhengtianyu2018@163.com
  • 基金资助:
    国家自然科学基金项目(21463016)

Abstract:

The corrosion behavior of Q235 steel in methanol medium in the presence of sulfuric acid and the inhibition properties of 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) for Q235 steel in methanol/sulfuric acid aqueous solutions were studied in the paper. The corrosion inhibition characteristics of [Bmim]Cl for Q235 steel were evaluated by static mass loss method, polarization curve method, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The corrosion inhibition mechanism of [Bmim]Cl was analyzed by quantum chemical calculation and molecular dynamics simulation. The corrosion rates of carbon steel increased with the increase of sulfuric acid in methanol. The results of experiments showed that the corrosion inhibition efficiency increased gradually with the increase of the concentration of [Bmim]Cl in methanol solution containing 59.51 ml 0.05 mol·L-1 H2SO4 aqueous solutions. When the concentration was 0.6 mol·L-1, the corrosion inhibition efficiency can reach the optimal, that is 90.63%. And [Bmim]Cl was a mixed inhibitor, which mainly controlled by the anodic reaction. Frontier orbitals analysis and Fukui function showed that the adsorption sites of ionic liquids on the surface of carbon steel were distributed on the imidazole ring and chemisorbed with Fe. The molecular dynamics simulation results showed that the inhibitor molecules were adsorbed parallel to the metal surface by cationic [Bmim]+, and the anion Cl- diffuses in solution to achieve the inhibition effect. The theoretical calculation results are consistent with the experimental results, that is, [Bmim] Cl has a good corrosion inhibition effect on Q235 steel in a methanol / sulfuric acid aqueous solution, laying a foundation for the research and application of new ionic liquid corrosion inhibitors.

Key words: ionic liquids, corrosion inhibitor, Q235 steel, electrochemistry, quantum chemical calculations, molecular simulation

摘要:

探究硫酸存在时Q235钢在甲醇中的腐蚀行为,以及离子液体1-丁基-3-甲基咪唑氯盐([Bmim]Cl)对金属表面的缓蚀作用。通过静态失重法、电化学测试、扫描电子显微镜来测定[Bmim]Cl对Q235钢的缓蚀性能。并利用量子化学计算和分子动力学模拟分析[Bmim]Cl分子的缓蚀机理。在甲醇中随着硫酸含量的增加碳钢的腐蚀速率增加。含有59.51 ml 0.05 mol·L-1 H2SO4的甲醇溶液作为腐蚀介质时,随着[Bmim]Cl浓度升高,缓蚀效率逐渐增大,当浓度为0.6 mol·L-1时,缓蚀效率达到最佳值,为90.63%,且[Bmim]Cl是主要控制阳极反应的混合抑制剂,SEM分析表明在含有缓蚀剂溶液中浸泡后的Q235钢表面相对于未加缓蚀剂更加平整。前线轨道分析和Fukui指数都表明,离子液体在碳钢表面的吸附位点分布在咪唑环上,与Fe发生化学吸附。分子动力学模拟结果表明缓蚀剂分子以阳离子[Bmim]+平行吸附于金属表面,阴离子Cl-扩散在溶液中的方式达到缓蚀的效果。理论计算结果与实验结果一致,即[Bmim]Cl在甲醇/硫酸水溶液中对Q235钢具有很好的缓蚀作用,为新型离子液体缓蚀剂研究应用奠定了基础。

关键词: 离子液体, 缓蚀剂, Q235钢, 电化学, 量子化学计算, 分子模拟

CLC Number: