Highly effective mild steel corrosion inhibition in 1 M HCl solution by novel green aqueous Mustard seed extract: Experimental, electronic-scale DFT and atomic-scale MC/MD explorations

The inhibitory behavior of Mustard seed extract for mild steel (MS) in HCl solution was explored. The extract structures were studied by FT-IR analysis connected with UV-Vis spectroscopy. The surface studies were accomplished using contact angle and SEM/AFM tests. The corrosion studies were scrutinized utilizing electrochemical techniques of weight loss, impedance spectroscopy (EIS), and potentiodynamic polarization at different temperatures (25, 35, 45 and 55 degrees C) and extract concentrations. To corroborate experiments, detailed theoretical studies were conducted. The EIS examination proved the maximum inhibition efficiency of 94% for 200 mg.L-1 of the extract. By enhancing the solution temperature, the steel resistance against corrosion decreased, and the efficiencies of 93, 90, 91, and 93% were obtained at 25, 35, 45, and 55 degrees C, respectively. Potentiodynamic polarization results demonstrated that the steel corrosion happened under control of anodic and cathodic reactions even at higher temperatures. The weight loss analysis proved 97% inhibition efficiency for the acid solution containing 200 mg.L-1 extract. The study of the adsorption isotherms showed that the adsorption of Mustard seed extract molecules was in the line of Langmuir isotherm. Electronic/atomic simulations proved the adsorption of Mustard seed extract molecules onto the steel substrate. (C) 2019 Elsevier B.V. All rights reserved.