An investigation of some Schiff bases as corrosion inhibitors for austenitic chromium-nickel steel in H2SO4

The corrosion inhibition of austenitic chromium-nickel steel by two Schiff bases, N-(1-toluidine)salicylaldimine and N-(2-hydroxyphenyl)salicylaldimin e, was investigated in sulphuric acid medium. The effect of concentration a nd temperature on inhibition properties was determined. It was found that w hen the concentrations of inhibitor were increased the inhibition efficienc ies (eta) and surface coverage (theta) increased. Some thermodynamic parame ters such as free energy of adsorption, DeltaG(ads)degrees, and enthalpy, D eltaH, were determined for the Schiff bases. Experimental results agree wit h the Temkin isotherm for N-(1-toluidine)salicylaldimine, but the Langmuir isotherm is more appropriate for N-(2-hydroxyphenyl)salicylaldimine.