A combined experimental and theoretical study of green corrosion inhibition of mild steel in HCl solution by aqueous Citrullus lanatus fruit (CLF) extract

The potentiality of Citrullus lanatus fruit (CLF) extract containing several phytochemicals (e.g., citrulline, hesperetin, resveratrol and riboflavin) for mitigating the corrosion of mild steel specimens in subjection to 1 M HCl was assessed from integrated experimental and electronic/atomic level theoretical perspectives. The corrosion inhibition characteristics were examined applying electrochemical (EIS and polarization) and surface morphological (SEM, AFM, contact angle) techniques. Additionally, the presence of major phytochemicals in CLF extract was explored by FT-IR spectroscopy combined with UV-Visible analyses. Based on electrochemical results, with the use of 800 ppm CLF extract 91% inhibition capacity was derived. The potentiodynamic polarization clarified the mixed inhibition effect of CLF extract with prevalence cathodic inhibition. Also, the graphical SEM/AFM results disclosed that the interactions of CLF extract molecules with steel surface greatly influenced the prevention of surface damage. The outcomes resulted from molecular simulation and quantum mechanics analyses further reflected the CLF extract compounds adsorption on steel surface. (C) 2019 Elsevier B.V. All rights reserved.