New azonitrile derivatives as corrosion inhibitors for copper in nitric acid solution

Abstract

The inhibitive effect of new synthesized azonitriles, namely 3-phenyl azo-2-amino-1,1,3-tricyano propene, 3-p-tolyl azo-2-amino-1,1,3-tricyano propene, 3-p-anisyl azo-2-amino-1,1,3-tricyano propene, 3-p-nitro phenyl azo-2 amino-1,1,3-tricyano propene, and 3-p-phenyl carboxylic azo-2-amino-1,1,3-tricyano propene on the corrosion of copper in nitric acid solution was investigated using chemical and electrochemical methods. The inhibition efficiency was found to increase with inhibitor concentration and decreased with rise in solution temperature. Various thermodynamic parameters were calculated and discussed in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied azonitriles acted as mixed inhibitors. The results revealed that these compounds were adsorbed onto the copper surface and the adsorption obeyed the Temkin adsorption isotherm. The quantum chemical calculations were in good agreement with the experimental results.