Herbal expired drug bearing glycosides and polysaccharides moieties as green and cost-effective oilfield corrosion inhibitor: Electrochemical and computational studies

Abstract

Considerable attention has been paid to utilizing eco-friendly and cost-effective corrosion inhibitors in oilfields. Regarding these criteria, the main objective of this work is the evaluation of the corrosion inhibition performance of an expired herbal drug on carbon steel in a 1.0 M HCl solution using electrochemical techniques. It was found that the herbal drug is an effective mixed-type inhibitor and the inhibition efficiency increased with an increase in concentration to achieve 97.5% at 1.2 g/L of the inhibitor. The adsorption model obeys the Langmuir adsorption isotherm out of both polarization and impedance results. Depending on the effect of temperature on the corrosion rate, the activation parameters Ea, ΔHao and ΔSao were estimated and discussed. The structural–corrosion inhibition relationships have been assessed using quantum chemical calculations and Monte Carlo simulations on the chief chemical constituents of the extract. The computational studies confirmed the formation of an adsorbed film on the metal surface through several active centers of polysaccharides and glycosides constituents besides nitrogen atoms of alkylamides ones. Also, they supported the interaction of the unshared electron pairs of O and N atoms with the d-orbitals of Fe which, played a vital role in the adsorption of herbal drug molecules on the carbon steel surface.