Vashishth Priya, Bairagi Himanshi, Sehrawat Rashmi, Mangla Bindu
Corrosion Testing Research Lab, Department of Chemistry, J.C. Bose University of Science and Technology, YMCAFaridabad, Haryana 121006, India.
ACS Omega. 2025 Feb 4;10(6):5332-5350. doi: 10.1021/acsomega.4c06238. eCollection 2025 Feb 18.
The efficacy of pharmaceuticals in mitigating corrosion on metallic substrates has led to the development of a new class of inhibitors that are economically efficient and offer significant environmental benefits. In the present study, for the anticorrosion action of loratadine (LT), 4-(8-chloro-5,6-dihydro-11H-benzo [5,6] cyclohepta[1,2-] pyridin-11-ylidene)-1-piperidinecarboxylic acid ethyl ester and its amine derivatives (LT1, LT2, and LT3), a theoretical study using DFT was conducted to elucidate the molecular interactions and complex formation mechanisms between these inhibitors and mild steel. The Δ values for the studied inhibitors-2.17 eV (LT), 3.904 eV (LT1), 3.906 eV (LT2), and 3.85 eV (LT3)-indicate that the LT inhibitor shows greater reactivity compared to the other LT amine derivatives, particularly in terms of electron donation to the metal substrate. After that, the corrosion inhibitory efficacy of parent molecule LT was examined on steel substrate in a medium 1 N hydrochloric and 1 N sulfuric acid and was found to have an efficiency of 98.52 and 80.58%, respectively, (308 K for 100 ppm concentration) deliberated through the electrochemical techniques (PDP and EIS) and gravimetric technique. The reduction in Cdl values from 684.06 to 43.15 μF/cm in 1 N HCl and from 693.41 to 83.91 μF/cm in 1 N HSO indicates an adsorption process in which inhibitor molecules displace water adsorbed on the metallic substrate, creating a barrier that prevents the metallic substrate from corrosive damage. The surface adsorption aligned with the Langmuir adsorption isotherm with Gibbs-free energy -51 kJ/mol in 1 N HCl and -49.23 kJ/mol in 1 N HSO. The AFM analysis with an average roughness of 16.29 nm in HCl and 49.23 nm in HSO validated LT to form a barrier on mild steel, opposing corrosion. The decelerative effect of LT inferred from theoretical and experimental data comply, making them credible corrosion inhibitors.
药物在减轻金属基底腐蚀方面的功效促使了一类新型缓蚀剂的开发，这类缓蚀剂经济高效且具有显著的环境效益。在本研究中，为了探究氯雷他定（LT）、4-(8-氯-5,6-二氢-11H-苯并[5,6]环庚并[1,2-b]吡啶-11-亚基)-1-哌啶羧酸乙酯及其胺衍生物（LT1、LT2和LT3）的防腐作用，采用密度泛函理论（DFT）进行了理论研究，以阐明这些缓蚀剂与低碳钢之间的分子相互作用和络合物形成机制。所研究缓蚀剂的Δ值——2.17 eV（LT）、3.904 eV（LT1）、3.906 eV（LT2）和3.85 eV（LT3）——表明，与其他LT胺衍生物相比，LT缓蚀剂表现出更高的反应活性，尤其是在向金属基底提供电子方面。此后，通过电化学技术（极化电阻法和电化学阻抗谱）和重量法，研究了母体分子LT在1 N盐酸和1 N硫酸介质中对钢基底的缓蚀效果，发现在100 ppm浓度（308 K）下，其缓蚀效率分别为98.52%和80.58%。在1 N HCl中，双电层电容（Cdl）值从684.06 μF/cm降至43.15 μF/cm，在1 N H₂SO₄中从693.41 μF/cm降至83.91 μF/cm，这表明发生了吸附过程，即缓蚀剂分子取代了吸附在金属基底上的水，形成了一个防止金属基底遭受腐蚀破坏的屏障。表面吸附符合朗缪尔吸附等温线，在1 N HCl中的吉布斯自由能为-51 kJ/mol，在1 N H₂SO₄中为-49.23 kJ/mol。原子力显微镜（AFM）分析表明，在HCl中平均粗糙度为16.29 nm，在H₂SO₄中为49.23 nm，验证了LT在低碳钢上形成了一个阻挡腐蚀的屏障。从理论和实验数据推断出的LT的缓蚀效果相符，这使得它们成为可靠的缓蚀剂。
