ADSORPTION MECHANISM OF BENZOTRIAZOLE FOR CORROSION INHIBITION OF COPPER-NICKEL ALLOY IN HYDROCHLORIC ACID

Abstract

ABSTRACT The inhibition of copper corrosion by Benzotriazole (BTA) in 5% HCl has been investigated by weight loss technique at different temperatures. Langmuir adsorption isotherm, Freundlich Adsorption Isotherm and Kinetic-Thermodynamic Model were used to describe the adsorption process depending on values of surface converge. Maximum value of surface converge was 0.998 for BTA at 35 o C and 15 g/l inhibitor concentration, while the lower value was 0.868 at 55 C and 1 g/l inhibitor concentration. The films formed on the copper-nickel alloy surface of BTA appeared to obey the Langmuir Adsorption Isotherm more than Freundlich adsorption isotherm. In the other hand, results showed that the Kinetic-Thermodynamic Model was unsuitable to fit the experimental data of the BTA of the present study. Keywords: adsorption isotherms, corrosion inhibition, copper-nickel alloy, benzotriazole, inhibitor efficiency INTRODUCTION Copper and its alloys are commonly employed as a material in heating and cooling systems due to their good thermal conductivity and mechanical properties. Hydrochloric acid pickling is extensively used for the removal of rust and scale on heat transfer in several industrial processes. However, these systems should be regularly cleaned from carbonates and oxides that diminish their heating transmission. Diluted hydrochloric acid is used to clean these surfaces; a corrosion inhibitor is added to avoid the action of this acid on copper. Corrosion inhibitor is a chemical substance when it is added with little concentration to environment effectively checks, decreases or prevents the reaction of metal with environment