Modelling the Inhibitory Effect of Moringa oleifera on Mild Steel Corrosion Using Nonlinear Adsorption, Dose–Response, and Multivariate Statistical Approaches

Abstract

Mild steel corrosion is one of the key problems of the industry as it has an economic effect and can easily be deteriorated in acidic conditions, which requires efficient and sustainable inhibitory measures. The application of synthetic inhibitors is, however, restricted by toxicity, environmental issues and cost, and available research on plant-based inhibitors is largely experimental and has not extensively incorporated the use of sophisticated statistical modelling. This knowledge gap explains why a full modelling framework is necessary to integrate experimental evidence and sound analytical methods to enhance predictions and mechanistic insights. The study purposes were to determine the inhibitory activity of the Moringa oleifera extract on mild steel corrosion by establishing the rate of corrosion, weight loss, the efficiency of the inhibitor, and surface coverage; modeling the adsorption behaviour by employing the Langmuir isotherm; examining the relationships between concentration and response; and selecting the most appropriate modelling framework. Primary experimental data collection was performed by gravimetric and gasometric methods, under controlled laboratory conditions. R version 4.4.3 was used to perform data analysis with linear regression, nonlinear least squares (NLS), log-logistic dose response modelling, Principal Component Analysis (PCA), and Akaike Information Criterion (AIC) to evaluate the model. Results indicate strong inhibition performance, with a significant adsorption constant (K = 1.1916, p = 0.0011) and excellent regression fit (R² = 0.98; F = 366.70; p = 1.31 × 10⁻⁶). In comparison to the linear model, the Langmuir model was better (AIC = -13.9402 vs 46.9929) and PCA showed that 99.40 percent of the variance is described by a single dominant factor. The study concludes that Moringa oleifera is a promising green corrosion inhibitor and the combined modelling method has a strong potential of offering an effective framework of optimising corrosion control measures