Unraveling the synergistic effect of cationic and anionic salt on the corrosion inhibition performance of Garcinia gummi-gutta leaf extract against mild steel in HCl medium

Abstract

Corrosion is a global concern as it poses major economic losses and safety concerns. An effective remedial measure has been the use of green corrosion inhibitors. Even though green corrosion inhibitors are nontoxic and biodegradable; its corrosion inhibition efficiency is less when compared to conventional synthetic inhibitors. The present work provides experimental evidences regarding the synergistic effect of cationic or anionic salt towards augmenting the corrosion inhibition efficiency of green inhibitors. Precisely, a thorough comparative analysis of the corrosion inhibition potential of the plant extract with either cationic or anionic salts has been carried out that provides sound basis for the effective industrial use of the technology. The corrosion inhibition performance of Garcinia gummi-gutta leaf extract along with 10 mM KI and 10 mM zinc acetate by weight loss method and electrochemical technique was analyzed. It was found that 6000 ppm plant leaf extract with KI has a corrosion inhibition efficacy of 97% and 91.6%, as analyzed by electrochemical impedance (EIS) and potentiodynamic polarisation (PDP) studies respectively. When combined with zinc acetate, 6000 ppm plant leaf extract exhibits an inhibitory efficacy of 89.7% and 84%, under EIS and PDP analysis respectively. UV Visible Spectroscopy was used to affirm the strong interaction of ionic salts with the heteroatom present in plant leaf extract and surface characterization using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) indicated the formation of protective layer of the plant extract on the mild steel surface. The findings support the notion that KI is more effective than zinc acetate at enhancing Garcinia gummi-gutta leaf extract's capacity for corrosion inhibition.