Evaluating two new synthesized S–N Schiff bases on the corrosion of copper in 15% hydrochloric acid

The inhibiting action of two new Schiff bases namely SB1: 2-({-1-methyl-3-[(2-sulfanylphenyl)imino]butylidene}amino)-1-benzenethiol and SB2: 2-({-1,2-diphenyl-2-[(2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenethiol on the corrosion of copper in hydrochloric acid has been studied. The Schiff bases were synthesized and studied as inhibitors for corrosion of copper. Results of electrochemical impedance and Tafel polarization measurements consistently identify both compounds as good inhibitors. Impedance spectroscopy revealed that the corrosion of copper in hydrochloric solution was influenced to some extent by mass transport since the Warburg impedance was observed in some cases. Polarization curves indicate that both studied Schiff bases act as mixed type (cathodic/anodic) inhibitors. Differences in inhibition efficiency between SB1 and SB2 are correlated with their chemical structures. Langmuir isotherm is found to provide an adsorption description of Schiff bases.