The Corrosion Inhibition of The Carbon Steel and Oil Pipelines in 1M HCl by Expired Lactulax and Triazepine Carboxylate Drugs

Corrosion in carbon steel and oil pipelines has adverse economic and environmental effects. Therefore, there is interest in utilizing inexpensive and environmentally friendly materials to prevent and inhibit corrosion. In this study, two expired drugs, Lactulose (La.) and Triazepine Carboxylate (TC), were investigated as potential inhibitors of steel corrosion in 1M HCl. The weight loss method and the potentiometric method were employed to calculate the inhibition efficiency (IEw%) of these compounds. The study examined the effect of inhibitor concentration and temperature on IEw%, and also involved calculating the activation energy and enthalpy change using the Arrhenius equation and transition state theory, according to the weight loss method, La. exhibits higher inhibition efficiency than TC. However, both inhibitors show nearly equal efficiency according to the potentiometric method. La. demonstrates greater stability and efficiency at elevated temperatures, as evidenced by Arrhenius plots and transition state analysis, which also involved calculating activation energy, enthalpy change, and entropy change. The corrosion process and inhibition were monitored by changes in voltage using a voltage and current meter, with Ag/AgCl used as a reference electrode. It was observed that La. exhibits shorter adsorption stability on the surface of carbon steel compared to TC, which contributes to its higher efficiency in inhibiting corrosion.