Response surface methodology and experimental evaluation of the inhibitory properties of corn leaf extract for aluminum corrosion in acid media

Abstract

Purpose This study aims to develop eco-friendly corrosion inhibitors for aluminum in acidic media by evaluating the corrosion inhibition properties of corn leaf extract (CLE) using response surface methodology (RSM) and experiments. Design/methodology/approach The RSM was combined with experiments to evaluate the corrosion inhibition properties of CLE on aluminum in acid media. Findings The effectiveness of the inhibition increased with increasing inhibitor concentration and time but decreased with increasing temperature. The corrosion inhibition mechanism revealed the corrosion process is spontaneous exothermic physical adsorption. Thermodynamic parameters revealed an activation energy between 32.1 and 24.7 kJ/mol, energy of adsorption between −14.53 and −65.07 and Gibbs free energy of −10.12 kJ/mol which indicated the CLE exothermically spontaneously physisorbed. A model was generated to estimate the effect of the process parameters (inhibitor concentration, reaction time and temperature) using the RSM. Optimization of the process factors was also carried out using the RSM. The percentage inhibition efficiency obtained experimentally (85.61%) was closely comparable to 84.89% obtained by the theoretical technique (RSM). The SEM observations of the inhibited and uninhibited Al samples demonstrated that CLE is an effective corrosion inhibitor for aluminum in acid media. Originality/value Results herein provide novel information on the possible application of CLEs as effective eco-friendly corrosion inhibitors.