Thermodynamic and adsorption studies on the corrosion inhibition of Zn by 2, 2'-Dithiobis(2,3-dihydro-1,3-benzothiazole) in HCl solutions

Abstract

The thermodynamics parameters and adsorption mechanism of 2,2'-dithiobis(2,3-dihydro-1,3-benzothiazole), DDBT, as a corrosion inhibitor for zinc in 0.5 M HCl solution were studied by different techniques. The used organic compound was prepared in our lab by a transformation reaction for thiol compound in the presence of ammonium per-sulfate. Potentiodynamic polarization, thermometric and gravimetric techniques, as well as, scanning electron microscope, SEM surface investigations were employed. The data of different techniques were compatible and confirmed the inhibition effect of DDBT. The potentiodynamic polarization data disclosed that the DTDBT molecules behave as a mixed-kind inhibitor. The different thermodynamic parameters about the corrosion and adsorption processes such as Ea, ∆Ha, ∆Sa, ∆G°ads, ∆H°ads and ∆S°ads were deduced to suggest the inhibition mechanism. The DDBT molecules are adsorbed on the Zn surface confirming the Langmuir isotherm model obeying a mixed mechanism (physical and chemisorption).