Protection performance of Azadirachta indica leaf essential oil on corrosion of plain carbon steel in weak HCl and NH₄Cl

Department of Mechanical Engineering, Covenant University, Ogun State, Nigeria

^* Corresponding Author: tolu.loto@gmail.com

Abstract

Azadirachta indica leaf essential oil (ADI) was assessed for its corrosion protection properties on plain carbon steel within 0.5 M HCl, 3.74 M NH₄Cl, 1 M HCl, and 5.61 M NH₄Cl. Weight loss data indicates ADI exhibited strong inhibition properties in HCl, with peak performance of 97.53% and 97.55% at 5% ADI. The results indicates strong molecular interaction between protonated ADI molecules and the charged steel surface. ADI showed poor inhibition at 1-4% ADI within NH₄Cl, at values below 50%. At 5% ADI concentration, the data considerably rose to 78.52% and 78.0% after 312 h. This shows ADI performance in NH₄C is significantly concentration dependent which limits it versatility compared to its performance in HCl solution. Standard error for ADI performance within 0.5 M HCl were extreme, suggesting thermodynamic stability of inhibitor molecules. Standard error were lower in 1 M HCl, 3.74 M NH₄Cl, and 5.61 M NH₄Cl. Numerical data showed a portion of ADI protection performance values generally exceeded 70%. Statistical analysis showed immersion duration was more dominant on the performance of ADI compared to ADI concentration, while ADI concentration wasmore influential in NH₄Cl.