Corrosion inhibition of mild steel in hydrochloric acid solution by quaternary ammonium salt derivatives of corn stalk polysaccharide (QAPS)

Abstract

Novel phosphorus-free corn stalk polysaccharide (PS) derivatives were prepared using 2,3-epoxypropyltrimethylammonium chloride, N-methyl imidazole, pyridine and epichlorohydrin as starting materials. The corrosion inhibition performance with their adsorption mechanisms for mild steel was studied in 1.0mol/L HCl solution by a series of techniques such as weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), electron scanning microscope (SEM) and XPS analysis. The values of apparent activation energy (Ea) for mild steel corrosion and ΔG0, ΔH0 and ΔS0 were calculated and discussed. The results suggested that the inhibitors were mixed ones with predominant anodic inhibition and the corrosion behavior in the presence of QAPSs can been explained by the adsorption film mechanism. Moreover, the adsorption process obeys Langmuir adsorption isotherm model and the N, C atoms of the heterocycle and the O atom of the hydroxyl group combined with the Fe element from the XPS spectra.