Inhibitory effect of expired glavox tablets on A36 carbon steel for optimized service life

Abstract This research delves into the potential of expired Glavox tablets, containing Amoxicillin and Clavulanic acid, as environmentally friendly substances to inhibit corrosion on A36 carbon steel in solutions of 1M HCl and 3.65 wt% NaCl. The findings from weight loss experiments in 1M HCl indicated a decrease in the corrosion rate, dropping from 1.24 mm y −1 for untreated specimens to 0.17 mm y −1 for specimens treated with 7.5 ml of Glavox solution. Similarly, in the 3.65 wt% NaCl solution, the corrosion rate reduced from 0.98 mm y −1 to 0.23 mm y −1 with the same concentration of inhibitor. Electrochemical assessments conducted in the HCl medium unveiled alterations in the corrosion potential (E corr ) from −0.48 V to −0.35 V, and a decline in the corrosion current density (i corr ) from 3.2 mA cm −2 to 0.42 mA cm −2 , indicating a blend of inhibitory characteristics. Within the NaCl medium, E corr transitioned from −0.45 V to −0.30 V, while i corr decreased from 2.9 mA cm −2 to 0.57 mA cm −2 . Studies on adsorption affirmed the robust adsorption capacity of Glavox on the steel surface, aligning well with Langmuir, Freundlich, and Temkin isotherm models. The formation of a barrier of protection on the inhibited samples was revealed by SEM/EDS examination of the surface morphology. The outcomes propose that expired Glavox tablets exhibit efficacy as corrosion inhibitors in acidic and saline settings, attaining an inhibition efficiency of up to 86%, predominantly through adsorption and the formation of a protective film.