Neem Leaf Extract as a Corrosion Inhibitor on Mild Steel in Acidic Solution

Abstract

The influence of neem leaf extract on corrosion inhibition of mild steel in 0.1 M HCl solution was studied using the weight loss method. Neem leaf extract which contains the double bond, carbonyl groups, and aromatic rings functional group as shown by the GCMS, phytochemical test, and FTIR analyses is one of the good natural plant extract that can be used as corrosion inhibitor. The weight loss on surface of mild steel at various inhibitor concentrations was determined. The highest inhibition efficiency of 93.24% was achieved using the neem leaf extract as corrosion inhibitor. Adsorption mechanism was investigated using Langmuir, Temkin, and Freundlich isotherms. Inhibitor adherence on the mild steel surface was spontaneous with the negative Gibb’s free energy value obtained. The mixed type adsorption mechanism (physisorption and chemisorption) is proposed for the inhibitor adsorption on mild steel surface. The inhibitor was adsorbed on the mild steel surface through adsorption of the phytochemical components on the surface of mild steel which protects the metal surface from corroding. The corrosion rate decreases from 0.001 to 0.0002MPY with increase in inhibitor concentrations and exposure time.