Corrosion inhibition of API 5L X56 Steel in HCl solution using expired dolutegravir: evaluation by weight loss and SEM–EDX techniques

Abstract

Corrosion of pipeline steels in acidic environments remains a major industrial concern, particularly during acid pickling, descaling, and oil well acidizing operations. API 5L X56 steel, extensively used in oil and gas transportation, is highly vulnerable to acid-induced corrosion. This study investigates the corrosion inhibition performance of expired Dolutegravir for API 5L X56 steel in 1.0 M HCl using weight loss and SEM–EDX analyses. The results showed that inhibition efficiency increased with inhibitor concentration, reaching a maximum value of 92.3%, indicating strong adsorption of Dolutegravir molecules onto the steel surface. Adsorption isotherm analysis suggests physisorption mechanism. Surface characterization revealed severe degradation in the uninhibited medium, whereas inhibited samples exhibited a smoother morphology with reduced corrosion damage. EDX analysis confirmed the presence of adsorbed protective species on the steel surface. The findings demonstrated that expired Dolutegravir acts as an efficient, eco-friendly, and cost-effective corrosion inhibitor, highlighting its potential application in sustainable corrosion control and pharmaceutical waste valorization.