CORROSION INHIBITION OF ZINC IN HYDROCHLORIC ACID MEDIUM USING UREA INHIBITOR

Abstract

The corrosion behavior of Zn in 1 M HCl solution containing various concentration of Urea range (10-3→ 5x 10-3) M at temperature range (285-328) K was investigated. The corrosion inhibitive action of Urea on Zinc metal was studied using weight loss measurement and analytical titration of the amounts of dissolved Zinc in acidic solution in presence and absence of Urea , the results showed that Urea caused to protection efficiency reached to 88% when (50)mM Urea concentration was used . The coverage (θ) of metal surface by Urea could be obtained from the rate of corrosion in the presence and absence of Urea in the acid solution. A linear relationship was found to exist between the value of (C/ θ) and the corresponding Urea concentration (C) indicating that the inhibition action to occur via adsorption mechanism. Changes in the free energy, enthalpy and entropy associated with Urea adsorption have been determined. Apparent energies of activation have been calculated for the corrosion process of Zinc in the acid from corrosion rates and Arrhenius Plots.