Evaluation of the Inhibitive Performance of Expired Bismuth Subcitrate and Nortriptyline Drugs as Corrosion Inhibitors for Carbon Steel in Sodium Chloride Solution

Despite the widespread use of corrosion inhibitors, the high cost and toxicity of some inhibitors, such as sodium chromate, hydrazine, and zinc arsenate, have limited their application. Many pharmaceutical compounds are non-toxic and biocompatible in nature. Therefore, in this study, two types of expired drugs, bismuth subcitrate and nortriptyline, were used as corrosion inhibitors for carbon steel in a ۳.۵ wt.% sodium chloride environment. Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to investigate the corrosion behavior of the samples. The effect of ۴۸ hours of immersion on the morphology of the corroded surface was examined. In addition, the effect of long-term exposure of the samples (۲۱۶ hours) in inhibitor-containing environments on weight change was evaluated. Based on the electrochemical test results, the maximum inhibition efficiency for bismuth subcitrate was ۷۲% at a concentration of ۳۰ ppm, while for nortriptyline it was ۷۹% at a concentration of ۲۰۰ ppm. Both inhibitors, at their optimal concentrations, approximately doubled the polarization resistance of carbon steel in the sodium chloride environment. In the long-term immersion test, nortriptyline exhibited significantly better performance, with an inhibition efficiency of ۸۳%, compared to ۵۰% for bismuth subcitrate. Therefore, it can be concluded that nortriptyline is a more suitable option than bismuth subcitrate for long-term corrosion inhibition.

کلیدواژه ها:

Inhibitor ، Expired drug ، Bismuth Subcitrate ، Nortriptyline ، Polarization ، Electrochemical impedance ، بازدارنده ، داروی منقضی شده ، بیسموت ساب سیترات ، نورتریپتیلین ، پلاریزاسیون ، امپدانس الکتروشیمیایی