Laboratoire d'Agroressources, Polymères et Génie des Procédés, Université Ibn Tofail, Faculté des Sciences, Kénitra, Morocco.
Phys Chem Chem Phys. 2018 Aug 1;20(30):20167-20187. doi: 10.1039/c8cp03226b.
Three new organic compounds primarily based on 8-hydroxyquinoline have been successfully synthesized and characterized via different spectroscopic methods (FTIR, 1H, and 13C NMR). The synthesized compounds, namely 5-propoxymethyl-8-hydroxyquinoline (PMHQ), 5-methoxymethyl-8-hydroxyquinoline (MMHQ) and 5-hydroxymethyl-8-hydroxyquinoline (HMHQ), were evaluated as corrosion inhibitors for carbon steel in 1 M HCl solution using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss measurements at 298 K. Electrochemical measurements confirmed that the newly synthesized 5-alkoxymethyl-8-hydroxyquinoline derivatives are mixed type corrosion inhibitors and confirmed maximum protection efficiencies of 94, 89 and 81% for PMHQ, MMHQ, and HMHQ, respectively, at the optimum concentration of 10-3 M. The EIS spectra confirmed a slightly depressed semi-circle profile with a single time constant in Bode diagrams for the three organic compounds over the whole concentration and temperature ranges studied. The adsorption of PMHQ, MMHQ, and HMHQ on the carbon steel surface followed the Langmuir adsorption isotherm. In addition, the kinetic and thermodynamic parameters for carbon steel corrosion and inhibitor adsorption, respectively, were determined and discussed. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses supported the formation of a protective film on carbon steel in the presence of PMHQ, MMHQ, and HMHQ. Density functional theory calculations (DFT) showed that the effectiveness of the inhibitive actions of the studied compounds correlates well with their electron donating ability, whilst Monte Carlo simulations revealed that the extent and favourability of adsorption of inhibitor molecules on the carbon steel surface establish their corrosion inhibition performances.
三种新型有机化合物主要基于 8-羟基喹啉，通过不同的光谱方法（FTIR、1H 和 13C NMR）成功合成并进行了表征。合成的化合物，即 5-丙氧基甲基-8-羟基喹啉（PMHQ）、5-甲氧基甲基-8-羟基喹啉（MMHQ）和 5-羟甲基-8-羟基喹啉（HMHQ），在 298 K 下，通过电化学阻抗谱、动电位极化和重量损失测量，被评估为 1 M HCl 溶液中碳钢的腐蚀抑制剂。电化学测量证实，新合成的 5-烷氧基甲基-8-羟基喹啉衍生物是混合类型的腐蚀抑制剂，在最佳浓度 10-3 M 时，分别对 PMHQ、MMHQ 和 HMHQ 表现出 94%、89%和 81%的最大保护效率。Bode 图中的 EIS 谱证实，在整个浓度和温度范围内，三种有机化合物的半圆弧轮廓略有压低，且具有单个时间常数。PMHQ、MMHQ 和 HMHQ 在碳钢表面的吸附遵循 Langmuir 吸附等温线。此外，分别确定并讨论了碳钢腐蚀和抑制剂吸附的动力学和热力学参数。扫描电子显微镜（SEM）和 X 射线光电子能谱（XPS）分析支持在 PMHQ、MMHQ 和 HMHQ 的存在下，在碳钢表面形成了一层保护膜。密度泛函理论计算（DFT）表明，所研究化合物的抑制作用的有效性与其供电子能力密切相关，而蒙特卡罗模拟表明，抑制剂分子在碳钢表面的吸附程度和有利程度建立了它们的腐蚀抑制性能。
