Highly efficient green corrosion inhibitor for mild steel in sulfuric acid: Experimental and DFT approach

Abstract

Chemical corrosion inhibitors are commonly used for protecting the metallic surface from corrosion. But these chemical inhibitors pollute the environment and make the residual water unfit for use. In contrast, green corrosion inhibitors (GCI) i.e., plants and their products are environment-friendly in nature and contribute towards sustainable developments. Petals of B. glabra were investigated as GCI for mild steel at different concentrations and temperatures by polarization, impedance spectroscopy, and gravimetric methods. SEM and metallurgical microscopy were used for the surface studies. Henry and Langmuir adsorption isotherms were used for adsorption studies. A computational (DFT) study was performed to augment experimental data. B. glabra shows 93.13 ± 0.02% corrosion inhibition efficiency for mild steel in 1.0 M H2SO4. The thermodynamic, kinetic, and DFT studies of the inhibitor/mild steel interface help in understanding the adsorption and corrosion mechanism. A relation between inhibition efficiency obtained from theoretical and experimental techniques was established. Waste water was analyzed for its biochemical assay after gravimetric studies, and was found within permissible limits. B. glabra extract was proved to be an effective GCI for protecting mild steel from acid corrosion and hence contribute towards sustainable developments by using natural material (plants and their products) without polluting the environment.