Elabbasy Hanaa M, Toghan Arafat, Gadow Hend S
Misr Higher Institute for Engineering and Technology, Mansoura 35522, Egypt.
Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11623, Saudi Arabia.
ACS Omega. 2024 Mar 7;9(11):13391-13411. doi: 10.1021/acsomega.3c10522. eCollection 2024 Mar 19.
The corrosion of iron in acidic environments has a negative impact on global industry. Herewith, the inhibitory effect of cysteine (Cys.) on mild steel (MSL) corrosion in different acidic solutions (1 M HCl, 1 M HSO, and 1 M HPO) was investigated through weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and theoretical calculations. The measurement results indicated that the adsorption of Cys. molecules on the metal surface caused corrosion inhibition. As a result, a protective layer or insoluble compound, or both, is obtained, blocking the active sites, preventing corrosion. The effectiveness (IE %) of the Cys. was enhanced by increasing concentration and lowering temperature. The maximum IE % of inhibition at 1 × 10 M of Cys. obtained are 97.3, 89.7, and 84.4% in HCl, HPO, and HSO solutions, respectively. At the same inhibitor concentration, the double-layer capacity decreased, and the charge-transfer resistance increased from 17.17 to 188.5, 3.564 to 31.91, and 1.325 to 8.715 Ω cm in HCl, HPO, and HSO solutions, respectively. Adsorption and PDP studies confirmed that it obeys the Langmuir adsorption isotherm and acts as a mixed-type inhibitor of physicochemical nature. The corresponding thermodynamic and kinetic parameters were also calculated and discussed. Moreover, the inhibitory effect on the surface was inspected by SEM. The findings demonstrated that the order of IE % using Cys as anticorrosion agent for MSL is HCl > HPO > HSO solutions.
铁在酸性环境中的腐蚀对全球工业有负面影响。据此，通过失重法、动电位极化（PDP）、电化学阻抗谱、扫描电子显微镜（SEM）和理论计算，研究了半胱氨酸（Cys.）在不同酸性溶液（1 M HCl、1 M H₂SO₄和1 M H₃PO₄）中对低碳钢（MSL）腐蚀的抑制作用。测量结果表明，Cys.分子在金属表面的吸附导致了腐蚀抑制。结果，获得了一层保护层或不溶性化合物，或两者兼有，从而阻断了活性位点，防止了腐蚀。Cys.的缓蚀效率（IE %）通过增加浓度和降低温度而提高。在HCl、H₃PO₄和H₂SO₄溶液中，1×10⁻³ M的Cys.获得的最大缓蚀效率分别为97.3%、89.7%和84.4%。在相同的缓蚀剂浓度下，双电层电容降低，电荷转移电阻在HCl、H₃PO₄和H₂SO₄溶液中分别从17.17增加到188.5、3.564增加到31.91和1.325增加到8.715 Ω·cm²。吸附和PDP研究证实，它服从朗缪尔吸附等温线，并且作为一种物理化学性质的混合型缓蚀剂起作用。还计算并讨论了相应的热力学和动力学参数。此外，通过SEM检查了表面的抑制效果。研究结果表明，使用Cys作为MSL缓蚀剂时，缓蚀效率的顺序为HCl > H₃PO₄ > H₂SO₄溶液。
