Performance Evaluation of Azadirachta indica as a Corrosion Inhibitor on Mild Steel

Abstract

This study explores the performance evaluation of Azadirachta indica (Neem) leaf extract as a corrosion inhibitor for mild steel  in 1 M H₂SO₄. The Azadirachta indica (Neem) leaves were sourced at the University of Nigeria, Nsukka. The leaves were prepared using extraction method. The leaf extract was subjected to metallurgical analysis such as phytochemical , pH where the values were determined ,  Fourier Transform Infrared Spectroscopy (FTIR) analysis was used to determine the functional groups that are associacted the extract. The Spark Analytical instrument was used to determine the chemical composition of the mild steel. The mild steel samples were subjected to further analyses through the use of scanning electron microscope (SEM)  attached Energy Dispersive Spectroscopy (EDX). This analytical technique was used to deterimne the morphology and elemental wt% in the samplee. The X-ray diffraction technique was used to determine the crystal structures. The weight loss mesurment  experiment was performed for 240hours because it gives a clear , measurable corrosion signal, reflects realisitc industrial exposure, and aligns with standard pratices in the field, making the results both reliable and comparable to existing research.  The results revealed that the extract significantly decreases corrosion, with inhibition efficiencies of up to 64.58% at 10 ml and 98.46% at 30 ml of H₂SO₄ concentration. The extract shows high inhibition efficiency, reaching up to 98.46% at a H₂SO₄ concentration of 30 ml. The Fourier Transform Infrared Spectroscopy (FTIR) analysis reveals the presence of Hydroxyl (OH) groups, Carbonyl (C=O), Amines (N-H) groups, and Aromatic (C=C) in the protective film formed by the leaf extract. The crystalline structure revealed by X-ray Diffraction (XRD) analysis includes peaks that correspond to many substances, including Fe(MgSO₄), FeS₂, Fe(ZnSO₄), CaCO₃, Fe₂O₃, and other compounds. According to the Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDX) analysis, the examined samples' shape and elemental weight (%) concentration are revealed. The presence of some compounds, such as Alkaloids (0.6%), flavonoids (5.8%), saponins (1.5%), tannins (3.6%), and phenols (7.8%) was confirmed by the phytochemical analysis. The leaf extract and 1M of H₂SO₄ were tested for acidity using a pH meter. According to the study, the leaf extract of Azadirachta indica shows promise as an eco-friendly corrosion inhibitor for mild steel in acidic environments, providing a possible industrial solution. The phytochemicals present provided the protective coating that forms on the mild steel surface,  as the extract functions as a mixed-type inhibitor. The study shows how Azadirachta indica leaf extract can be used to prevent mild steel from corroding in 1M H₂SO₄ with respect to time and increasing concentration; the extract's inhibitory action improves greatly and better; the 30 ml concentration showed the maximum inhibition efficiency (%IE). According to these results, the leaf extract of Azadirachta indica shows promise as a natural corrosion inhibitor for mild steel in acidic conditions.