Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V University in Rabat, Av. Ibn Battouta, PO Box 1014, Agdal-Rabat, Rabat, Morocco.
Laboratory of Catalysis and Corrosion of Materials, Faculty of Sciences, Chouaib Doukkali University, PO Box 20, M-24000, El Jadida, Morocco.
Environ Sci Pollut Res Int. 2024 Jul;31(31):43757-43780. doi: 10.1007/s11356-024-34055-6. Epub 2024 Jun 22.
The present study focuses on an environmental approach based on the use of an eco-friendly corrosion inhibitor from the Citrullus colocynthis fruit extract for enhancement corrosion resistance of carbon steel (C-S) in acid medium as an alternative to various organic and non-organic chemical inhibitors. The evaluation of the inhibition properties of the fruit methanolic extract of Citrullus colocynthis (CCE) were performed in molar hydrochloric acid (1 M HCl) medium using gravimetric and electrochemical (potentiodynamic polarization and AC impedance) techniques as well as surface analyses. CCE is rich in amino acids, mainly citrulline and β-(pyrazo-1-yl)-L-analine molecules. Based on the weight loss evaluation, the results demonstrated that this plant extract acts as an effective corrosion inhibitor and a protection level of 93.6% was attained at 500 ppm of CCE after 6 h of metal exposure at 303 K. According to polarization curves, CCE functions as a mixed-type inhibitor. In addition, AC impedance analyses have shown that the incorporation of CCE into the corrosive solution leads to a decrease in load capacity, while improving the charge/discharge function at the interface. This suggests the possibility of the formation of an adsorbed layer on the C-S surface. In addition, scanning electron microscope (SEM) observation, contact angle measurements, and Fourier-transform infrared spectroscopy (FTIR) analyses supported the development of a protective film over CS substrate surface afterwards addition of CCE. Langmuir and/or Temkin isotherms can be used to characterize the adsorption of this organic inhibitor on the C-S surface. X-ray photoelectron spectroscopy (XPS) has revealed that the inhibiting effect of CCE on the corrosion of C-S in 1 M HCl solution is mainly controlled by a chemisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where CCE molecules are incorporated. In order to understand the relationship between the molecular structure and anti-corrosion effectiveness of these inhibitor molecules, quantum chemical studies were carried out using density functional theory (DFT) and molecular dynamics (MD) simulation.
本研究采用一种环保型缓蚀剂，从苦瓜果实提取物中提取，以增强碳钢（C-S）在酸性介质中的耐腐蚀性，替代各种有机和无机化学抑制剂。采用重量损失评估法，在 1M 盐酸（1M HCl）介质中，使用电化学（动电位极化和交流阻抗）技术以及表面分析对苦瓜果实甲醇提取物（CCE）的缓蚀性能进行评价。CCE 富含氨基酸，主要是瓜氨酸和β-（吡唑-1-基）-L-丙氨酸分子。结果表明，这种植物提取物在 303K 下 6 小时的金属暴露时间内，浓度为 500ppm 时，该植物提取物作为一种有效的缓蚀剂，其腐蚀保护效率达到 93.6%。根据极化曲线，CCE 作为一种混合型抑制剂。此外，交流阻抗分析表明，将 CCE 加入到腐蚀性溶液中会降低负载能力，同时改善界面的充放电功能。这表明在 CS 表面可能形成了吸附层。此外，扫描电子显微镜（SEM）观察、接触角测量和傅里叶变换红外光谱（FTIR）分析都支持在添加 CCE 后在 CS 基底表面形成一层保护膜。Langmuir 和/或 Temkin 等温线可用于描述这种有机抑制剂在 C-S 表面的吸附。X 射线光电子能谱（XPS）表明，CCE 对 C-S 在 1M HCl 溶液中腐蚀的抑制作用主要通过化学吸附过程控制，抑制层由铁氧化物/氢氧化物混合物组成，其中包含 CCE 分子。为了理解这些抑制剂分子的分子结构与防腐效果之间的关系，我们采用密度泛函理论（DFT）和分子动力学（MD）模拟进行了量子化学研究。
