Abstract

The corrosion inhibition of mild steel by a drug substance, namely piroxicam, in HCl (1 M) solution was investigated. The Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique were used. EIS measurements showed larger capacitive loops in the presence of piroxicam. The inhibition efficiency was found to be dependent on the piroxicam concentration. From the polarization curves the corrosion current density (\({{i}_{{{\text{cor}}}}}\)) decreased from 109.4 to 16.93 μA/cm². The adsorption mode of the drug obeys to the Langmuir isotherm model. The free energy of adsorption (∆G_ads) revealed a spontaneous process with a mixed interaction type i.e. physical and chemical. The kinetic study was conducted using the weight loss technique at the optimal piroxicam concentration (600 ppm). The density functional theory (DFT) method was used to determine the principal species, neutral or ionized drug, involved the inhibition mechanism. Scanning electron microscopy (SEM) was carried out for the surface characterization of the carbon steel after immersion in the aggressive medium in the absence and presence of the drug substance.

中文翻译：

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用非甾体抗炎药控制HCl电解液中低碳钢的腐蚀：电化学和动力学研究

摘要

研究了一种药物物质吡罗昔康在HCl（1 M）溶液中对低碳钢的腐蚀抑制作用。使用了电化学阻抗谱（EIS）和电位动力学极化技术。EIS测量显示在吡罗昔康存在下较大的电容环路。发现抑制效率取决于吡罗昔康的浓度。从极化曲线来看，腐蚀电流密度（\（{{i} _ {{{\ text {cor}}}}} \））从109.4降至16.93μA/ cm ²。药物的吸附模式服从Langmuir等温线模型。吸附自由能（∆ G _ads）揭示了一种自发过程，具有混合相互作用类型，即物理和化学。使用减肥技术在最佳吡罗昔康浓度（600 ppm）下进行动力学研究。密度泛函理论（DFT）方法用于确定主要种类，中性或离子化药物，涉及抑制机理。在不存在和存在药物的情况下，在浸入侵蚀性介质中后，对碳钢的表面特性进行了扫描电子显微镜（SEM）。