Imidazobenzimidazole hydrochloride derivatives as steel inhibitors in hydrochloric acid

The influence of substituted 2-(4-fluorophenyl)-9-R-imidazo[1,2-a]benzimidazole hydrochloride (where R = -CH 3 (1), -C 2 H 5 (2), -C 2 H 4 N(C 2 H 5 ) 2 (3), -C 3 H 7 (4), -C 4 H 9 (5)) on the corrosion of low carbon steel in 1 M hydrochloric acid solution was studied by gravimetric, temperature-kinetic, polarization, and impedance spectroscopy methods.It was found that the substances studied are effective inhibitors of acid corrosion of low carbon steel.It was shown that the protective effect of substituted imidazobenzimidazole hydrochlorides depends on the nature of the radical (R).Based the protective effect values, the radicals can be arranged in the series: methyl > ethyl  butyl > N,N-diethylethyleneamine  propyl.The protective effect of the compounds depends on the concentration and temperature.It was established that the protective effect of compounds 2-5 increases with increasing temperature.It was shown that the degree of coverage of the steel surface with inhibitors 2-5 increases with temperature.These additives reduce the effective activation energy of the corrosion process.The investigated imidazobenzimidazole derivatives affect the partial electrode reactions of the corrosion process.At the lowest concentration, additives 1-4 reduce the rate of the cathodic and anodic reactions.Additive 5 reduces the cathodic reaction rate and stimulates the dissolution of steel.Introduction of organic additives into the acid leads to a decrease in the corrosion potential of steel.