Eco-conscious corrosion inhibitor synthesis via Soxhlet extraction: experimental study in HCl 1M and theoretical analysis using DFT and MC simulations

Abstract

This study investigates the inhibitory potential of a hydroalcoholic extract from tea waste, using the Soxhlet method, against C38 corrosion in hydrochloric acid. Electrochemical tests, including EIS and PDP, evaluated the impact of extract concentration and immersion time on corrosion inhibition. SEM/EDS analysis was performed to examine the adsorption process. The results show that inhibitor concentration significantly affects corrosion inhibition, with inhibitory efficiency (IE) values up to 97.98% according to IE and Tafel curves. Increasing extract concentration enhances corrosion inhibition via surface adsorption, following the Langmuir model, resulting in a gradual increase in charge transfer resistance over time. Maximum inhibitory efficiency is reached after 6 hours, demonstrating time-dependent corrosion inhibition. SEM analysis confirms the adsorption mechanism. In summary, this study highlights the inhibitory potential of green tea waste extracts against C38 steel corrosion in hydrochloric acid, suggesting sustainable corrosion protection methods. Theoretical methods, including DFT and MC approaches, were used to analyse the interactions between hydrochloric acid, water, and the iron surface, as well as the adsorption of catechin on Fe (110) and Fe2O3 (110) surfaces. DFT results align well with MC simulations and experimental measurements, revealing a significant correlation between molecular structure and inhibitory efficacy.