Mathematical Modelling and Corrosion Inhibition Studies of Psidium guajava Extracts on Mild Steel in Industrial Environments

This study investigated the effect of Psidium guajava extracts as a green corrosion inhibitor on mild steel in different media (0.5 M NaOH and 1.0 M NaOH) environments. The mild steel samples were preweighed in each of the media with different inhibitor concentrations. The logarithmic, quadratic and cubic models were developed using a computer-aided statistical modelling technique. A critical analysis of the different models in terms of the coefficient of determination (R2) value shows that the cubic models had the best correlation of 1.0 (perfect correlation). Consequently, the various cubic model equations for corrosion rate profiles of leaf extracts in 0.5 M and 1.0 M NaOH environments were further transformed into two generalized forms using MATLAB 15.0 and the cubic model equations with a coefficient of determination (R2) value of 1.0 showing perfect correlation of the data obtained. Confirmatory, corrosion rates were calculated using the developed equations, compared with the experimental data and found satisfactory. The predicted corrosion rate of the samples was found to be close to the experimentally observed values. The results of the model equations showed that the trend represented in the experimental data was almost perfectly captured by the cubic function. The results show good potential for application in nanomaterials, metallurgical systems, biostructure and manufacturing industries. Therefore, controlling the corrosion of mild steel through novel inhibitor systems and developing a modelling tool that can mimic the exact corrosion process instead of costly experiments are important contributions of the work.