Thermodynamic Characteristics of Camel’s Urine as an Inhibitor for Mild Steel in 1.5 M H₂SO₄ Acid Solution

Abstract

Problem statement: The corrosion inhibition of mild steel in 1.5 M H₂SO₄ by Camel’s Urine (CU) addition was evaluated at five different temperatures in the range from 30-70°C by weight loss measurements. CU acts as a good inhibitor for the corrosion of mild steel in 1.5 M H₂SO₄. The value of inhibition efficiency increases with increasing both inhibitor concentration and solution temperature. Approach: The adsorption of CU constituents on the mild steel surface obeys the Langmuir adsorption isotherm suggesting a monolayer adsorption of CU species. Thermodynamic parameters for CU adsorption and mild steel corrosion were evaluated. The negative values of (ΔG^o_ads) emphasize the spontaneity of the adsorption process and stability of the adsorbed layer. Results: The estimated high, positive value of ΔH^o_ads ensures that CU species is adsorbed chemically on mild steel surface. All values of E^*_app for mild steel corrosion in inhibited solutions were lower than that for the uninhibited solution indicating the occurrence of chemisorption mechanism. Conclusion: The surface morphology of mild steel in absence and presence of inhibitor revealed that with increasing both CU concentration and solution temperature, mild steel surface is modified and looks smooth. Good correlation between the inhibitor constituents and its inhibitory action was obtained.