Synthesis and assessment of Gemini cationic surfactants as inhibitors for corrosion of carbon steel in hydrochloric acid

Abstract

Novel mono, di and tetra cationic surfactant (CS) molecules were synthesized by quaternization reaction of diamide with cetyl-2-chloroacetate with different ratio 1:1, 1:2 and 1:4. The chemical structures of the synthetic compounds were proven by FTIR and 1HNMR. The synthetic cationic surfactants were examined as corrosion inhibitors for carbon steel (CSt) in 1.0 M HCl solutions using chemical and electrochemical measurements. Some surface-active properties were determined and linked to the inhibition process. The inhibition efficiency increases with increasing concentration of CS molecules and decreasing temperature. Potentiodynamic polarization technique showed that the three CS molecules are classified as mixed inhibitors. The inhibition process was explained by its spontaneous adsorption on the surface of CSt, according to Langmuir isotherm. The results confirmed that the cationic surfactants successfully inhibited the corrosion of CSt in the investigated corrosion medium and the inhibition efficiency reached 96.08%.

Keywords

• Cationic surfactants
• carbon steel
• polarization
• corrosion inhibitors
• adsorption