Investigation of corrosion inhibition of mild steel in 1 M HCl by 3-oxo-[1,4]- benzothiazine derivative (T1) using experimental an d theoretical approaches

摘要

(Z)-2-benzylidene-2H-[1,4]benzothiazin-3-one (T1) h as been evaluated as a corrosion inhibitor for mild steel using weight loss and electrochemical polarization (EIS). The study was also complemented by quantum chemica l calculations. The inhibition efficiency (E%) increa sed with increasing (T1) concentration, showing a m aximum E% of 95% at 308 K at 10-3M. The electrochemical study reveals that this compound is an cathodic inhibito r and corrosion current density is the order 120 μ A/cm2 of (T1) at the optimum concentration. EIS res ults show that the change in the impedance parameters (Rct and Cdl) wi th concentration of (T1) is indicative of the adsor ption of molecules leading to the formation of a protective layer on the surface of mild steel. A good fit to L angmuir adsorption isotherm was obtained between surface co verage degree and inhibitor concentration. The resu lts obtained by weight loss measurements are consistent with the results of the electrochemical study. Qua ntum chemical approach used to calculate electronic prop erties of the molecule to ascertain the relation be tween inhibitive effect and molecular structure.