Protection of carbon steel against corrosion in hydrochloric acid solution by some synthesized cationic surfactants

Abstract

A series of some cationic surfactants was synthesized namely: N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(dodecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (DDAC); N,N,N-tris(hydroxymethyl)-2- oxo-2-(2-(2-(tetradecanoyloxy) ethoxy) ethoxy) ethanaminium chloride (TDAC) and N,N,Ntris( hydroxymethyl)-2-oxo-2-(2-(2-(hexadecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (HDAC). Their chemical structures were characterized using FTIR and ¹HNMR spectroscopy. Corrosion inhibition performance of these compounds on carbon steel in 0.5 M HCl was studied using weight loss and potentiodynamic polarization methods. It was seen that the three synthesized cationic surfactants decreased the corrosion rate of mild steel in acidic medium due to the adsorption on the metal surface. And it was found that the inhibition efficiency increased with increasing the inhibitor concentration. The adsorption of inhibitors on the carbon steel surface obeys modified Langmuir equation which named Villamil isotherm adsorption. Polarization curves show that the synthesized inhibitors are mixed-type inhibitors in 0.5 M HCl. ΔG_ads⁰ were ranged from–31.65 to–33.40 kJ mol^–1 which indicate that the adsorption process is mixture between physical and chemical adsorption.