Cross-linked poly(N-alkyl-4-vinylpyridinium) iodides as new eco-friendly inhibitors for corrosion study of St-37 steel in 1 M H2SO4

Abstract

Cross-linked poly (N-alkyl-4-vinylpyridinium) iodides abbreviated as P4-VPMI, P4-VPOI and P4-VPDI, were synthesized from quaternization of poly(4-vinyl pyridine) cross-linked with 2% DVB, by three alkyl iodides [methyl iodide (MI), octan iodide (OI) and decan iodide (DI)] in acetonitrile at room temperature. Then, their effect as new eco-friendly polymeric inhibitors was investigated in the corrosion process of St-37 in 1 M H2SO4. Formation of the inhibitors was approved by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR) techniques. Furthermore, their inhibition performance was studied using weight loss measurements, potentiodynamic polarization (tafel), and electrochemical impedance spectroscopy (EIS). By comparison of the inhibitive behavior of three inhibitors using mentioned methods and according to the obtained results, it was clearly found that, by adding all inhibitors into the corrosive solution (1 M H2SO4) and also with increasing of the inhibitors concentration, the steel corrosion is greatly reduced. The results also showed that, inhibition efficiency (%E) was decreased by increasing the length of carbon chain of the alkyl group. Therefore among the three inhibitors, P4VPMI with a concentration of 0.04 g l−1 has the best inhibition effect on the corrosion of St-37. Furthermore, the value of $$\Delta G^{0}$$ is found to be − 30.75 kJ mol−1; probably means that the adsorption of the inhibitors on St-37 surface involves both physical and chemical adsorption.