Exploring the potentials of mango-orange leaf extract as an inhibitor on carbon steel in an acidic medium: Optimization, kinetics, and thermodynamics

Corrosion of metals has been described as the destruction and deterioration of metallic material because of its reaction to an aggressive environment. This study investigated the performance optimization, mechanistic, and thermodynamic parameters of the inhibitive properties of the blend of mango and orange leaf extract (MOEx) on a carbon steel surface, and the optimization of the corrosion inhibition process in three different acid concentrations, varying temperature, inhibition concentrations, and exposure time via Response surface methodology (RSM). The functionality, phytochemical groups, surface morphology, and elemental composition of the MOEx were studied using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The effects of optimized variables on corrosion inhibition were examined. The result confirmed optimum inhibition efficiency of 96 % corresponding to MOEx concentration, temperature, and time of 450 ppm, 30 0 C, and 3 h recorded at an optimum acid concentration of 1.3 M of H 2 SO 4 . The mechanistic outcome of the corrosion inhibition occurred via adsorption at R 2 ≤ 0.9938, was also studied by applying the Langmuir, Freundlich, El–Awady, and Temkin's adsorption isotherms. The values of activation energy, enthalpy, and Gibbs’ free energy affirmed the stability of the inhibitor-carbon steel surface at optimum conditions. The investigation has revealed that the blend of mango and orange leaf extract is a promising, scalable corrosion inhibition solution.