Novel use of kitchen waste: protection of boiler quality steel from corrosion in acidic media using onion waste

An eco-friendly approach to inhibit the corrosion of boiler quality (BQ) steel by onion waste in acidic media was investigated. The extract from onion peel was characterized using the conventional extraction method and was characterized using HPLC. The efficacy of the onion peel extract (OPE) as a green corrosion inhibitor was studied using the weight loss method and a variety of electrochemical techniques, including open-circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The Tafel polarization revealed that at 200 mg L-1 of onion peel extract (OPE), corrosion current density was reduced maximum in both 1 (M) HCl and 0.5 (M) H2SO4 media. From the electrochemical impedance spectroscopy studies, the maximum inhibition efficiencies of 91.30% and 90.71% were found at 200 mg L-1 in 1 (M) HCl and 0.5 (M) H2SO4, respectively. The Langmuir isotherm was determined to be the best-fitting model, and the thermodynamic parameter, such as free energy Delta G degrees(ads), was computed, which indicated the physisorption of OPE onto the BQ surface. In theoretical investigations, density functional theory DFT was used to determine the adsorption efficiency and reactive sites of the OPE molecule by exploring various quantum chemical parameters.