EFFECT OF CONCENTRATION, CONTACT TIME AND TEMPERATURE ON INHIBITORY POTENTIAL OF GREEN INHIBITORS CASE STUDY: ZEA MAYS COBS EXTRACT ON MILD STEEL

Abstract

The inhibitive effects of acid extracts of Zea may scobs on the corrosion of mild steel in 1M H₂SO₄ solution were investigated. Experiments were performed by varying immersion period, concentration of the inhibitor and the reaction temperature. The inhibition efficiency of the extract obtained from weight loss method was found to increase with increase in concentration of the extracts. The highest inhibition efficiencies observed was at 0.4 % (v/v) which was 89.68%.The results showed that the corrosion rate of mild steel in 1M H₂SO₄acid decreased with increase in extract concentration. Thermodynamic studies revealed a mechanism of physical adsorption of plant extract on the surface of the metal. The data obtained were fitted into Langmuir isotherm, the energy of activation (E_A) was found to decrease from 22.01kJmol^-1 to 5.15 kJmol^-1 with increase in inhibitor concentration of extract. The calculated values of Gibbs free energy are in range of -10.24 kJmol^-1 to -11.28 kJmol^-1 for the extract. The Kinetic studies of the reaction process revealed a first order reaction.