Experimental and Theoretical Studies on Corrosion Inhibition Effect of Synthesized Benzothiazole Derivatives on Mild Steel in 15% HCl Solution

摘要

Two benzothiazole derivatives, namely, (Z)-5-(4-chlorobenzylidene)-3-(benzo[d]thiazol-2-yl)-2-(4- methoxyphenyl)thiazolidine-4-one (CBTMT) and (Z)-5-(4-methoxybenzylidene)-3-(benzo[d]thiazol- 2-yl)-2-(4-methoxyphenyl)thiazolidine-4-one (MBTMT) were synthesized in the laboratory and theircorrosion inhibition performance on mild steel in 15% HCl solution was studied by means of weightloss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)techniques. The inhibition efficiency of each inhibitor increased with increasing the concentration ofinhibitor. According to weight loss measurements, the inhibitors CBTMT and MBTMT showcorrosion inhibition efficiency of 95.8 and 97.5% respectively, in 150 ppm concentration, at 303 K.Polarization studies showed that corrosion current density decreased in presence of both the inhibitorsin comperision to in absence of inhibitors. The thermodynamic adsorption and activation parameterswere evaluated for corrosion inhibition process.The adsorption of inhibitors on the mild steel surfaceobey Langmuir adsorption isotherm. The surface analysis of uninhibited and inhibited mild steelsamples was performed by scanning electron microscopy (SEM), energy dispersive X-rayspectroscopy (EDX) and atomic force microscopy (AFM). Quantum chemical parameters calculatedby Density functional theory (DFT) were correlated with the experimental results.