文家新.硫酸介质中咪唑-4-甲基亚胺基硫脲对碳钢的缓蚀作用[J].表面技术,2024,53(6):123-132.
WEN Jiaxin.Corrosion Inhibition Effect of Imidazol-4-methylimine Thiourea for Carbon Steel in Sulfuric Acid Medium[J].Surface Technology,2024,53(6):123-132 |
| 硫酸介质中咪唑-4-甲基亚胺基硫脲对碳钢的缓蚀作用 |
| Corrosion Inhibition Effect of Imidazol-4-methylimine Thiourea for Carbon Steel in Sulfuric Acid Medium |
| 投稿时间：2023-03-01 修订日期：2023-06-14 |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.06.011 |
| 中文关键词: 缓蚀作用 硫酸介质 咪唑-4-甲基亚胺基硫脲 碳钢 电化学测试 理论计算 |
| 英文关键词:corrosion inhibition effect sulfuric acid medium imidazol-4-methylimine thiourea carbon steel electrochemical test theoretical calculation |
| 基金项目:重庆市教委科学技术研究项目(KJQN202103202，KJQN202103210);重庆工业职业技术学院博士研究基金(2022GZYBSZK2-11) |
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| 中文摘要: |
| 目的 碳钢因其优异的性能被广泛应用于工农业中，为解决碳钢在酸性介质中的腐蚀问题。方法 以氨基硫脲和咪唑-4-甲醛为原料合成了Schiff碱化合物咪唑-4-甲基亚胺基硫脲(MIT)，采用傅里叶红外光谱(FT-IR)、核磁共振谱(NMR)及质谱(EI-MS)表征了其分子结构。将MIT化合物作为H2SO4介质中碳钢的缓蚀剂，分别采用静态失重法、电化学测试及腐蚀形貌分析研究了其在0.5 mol/L H2SO4溶液中对碳钢的缓蚀性能，通过吸附模型、X-射线光电子能谱(XPS)等方法研究了MIT分子在碳钢表面的吸附行为，采用密度泛函理论(DFT)和分子动力学模拟(MD)方法进行了理论计算研究。结果 MIT在H2SO4溶液中对碳钢的缓蚀效率随其添加量的增大而提高，随腐蚀环境温度的提高而下降，293 K下其在0.5 mol/L H2SO4溶液中的最佳质量浓度为240 mg/L，对应的缓蚀效率可达95.4%。MIT是一种混合型缓蚀剂，电化学缓蚀机理可解释为“几何覆盖效应”。在碳钢表面的MIT分子吸附属于化学和物理混合吸附( =−31.62 kJ/ mol，293 K)，且服从Langmuir吸附定律。结论 MIT可有效抑制碳钢在H2SO4溶液中的腐蚀，MIT的合成既为H2SO4溶液中碳钢的腐蚀防护开发了一种有效方法，也为其他酸性介质中碳钢缓蚀剂的开发提供了新思路。 |
| 英文摘要: |
| Carbon steel is widely used in industrial and agricultural production by virtue of its superior performance. However, carbon steel is prone to be corroded in the acidic medium, which may cause huge economic loss or even accidents. The addition of corrosion inhibitors is considered as a straightforward and effective way to address this problem. In this work, a Schiff base compound of imidazol-4-methylimine thiourea (MIT) was successfully synthesized with thiosemicarbazide and imidazole-4-carbaldehyde as the raw materials through a simple one-step reaction with the yield of 79%, and its chemical structure was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR) and electron impact mass spectrometry (EI-MS). The MIT compound was explored as an effective corrosion inhibitor for carbon steel in the H2SO4 medium. The inhibition performance of MIT in 0.5 mol/L H2SO4 solution was evaluated by gravimetric measurements, electrochemical tests, and corrosion morphology analyses. The adsorption behavior of MIT molecules on the carbon steel surface was examined by the adsorption model and X-ray photoelectron spectroscopy (XPS) analyses, and the theoretical calculation study was conducted using density functional theory (DFT) and molecular dynamics (MD) methods. The test results showed that the inhibition efficiency of MIT for carbon steel in H2SO4 solution increased with enhancing inhibitor concentration and decreased with rising temperature. The inhibition efficiencyvalue of MIT could reach 95.4% at an ideal concentration of 240 mg/L at 293 K. MIT acted as a mixed-type corrosion inhibitor that could block both anodic and cathodic corrosion reactions. The electrochemical inhibition mechanism could be explained with "geometric blocking effect". With the addition of MIT, the double capacitance at the carbon steel/solution interface dropped, while the charge transfer resistance increased significantly. The metallographic image on the inhibited carbon steel surface indicated that the corrosion degree dropped apparently. The physical-chemical mixed adsorption of MIT molecules existed on the carbon steel surface, which obeyed the Langmuir adsorption isotherm, was a thermodynamic spontaneous adsorption process ( = −31.62 kJ/mol, 293 K). The heteroatoms of N, S and other unsaturated groups in the MIT molecule contained large number of lone pairs that could be ligated with the unoccupied d orbitals of Fe atom, thus producing the chemical adsorption of MIT molecules on the carbon steel surface, which was demonstrated by XPS analyses. The results of the theoretical calculations highlighted that the MIT compound could be strongly adsorbed on the carbon steel surface. The low ΔEgap and Eads values between Fe (110) surface and MIT molecules were calculated to be 400.70 and −1 415.92 kJ/mol, respectively, further implying that MIT had a strong capability to build a barrier against the carbon steel corrosion. MIT can effectively suppress the corrosion process of carbon steel in H2SO4 solution, which originates from two aspects. First, MIT molecules can be adsorbed on carbon steel to form a strong protective film that suppresses the active sites on the carbon steel surface. Otherwise, the addition of MIT decreases the aggressive ions of the solution and thus retards the corrosion process. The synthesis of MIT inhibitor not only offers a valid way to inhibit the corrosion of carbon steel in H2SO4 solution, but also opens a new avenue in exploring the corrosion inhibitor for carbon steel in other acidic media. |
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