Inhibition of corrosion of mild steel by sodium n,n-diethyl dithiocarbamate in hydrochloric acid solution

Abstract The effect of sodium n,n-diethyl dithiocarbamate (SDEDTC) on the corrosion of mild steel in 0·5 mol L-1 HCl solution was studied using weight loss and potentiodynamic polarisation methods. Experimental data revealed that SDEDTC acted as an inhibitor in the acid environment and, furthermore, that the compound was a mixed type inhibitor, predominating as a cathodic inhibitor. It was found that the inhibition efficiency increased with an increase in SDEDTC concentration at temperatures in the range 303–333 K. The experimental data for the inhibitor fitted the Flory–Huggins adsorption isotherm and the El–Awady thermodynamic kinetic model. The corrosion inhibition mechanism of SDEDTC on mild steel in HCl solution was also investigated by infrared spectra and electron probe microanalysis methods. The process of inhibition is attributed to the formation of an adsorbed film on the metal surface, which protects the metal against corrosive agents.