Synthesis and construction of a highly potent hybrid organic/inorganic anti-corrosive pigment for effective corrosion control of mild steel in simulated seawater

Abstract

The major goal of this research was development of a corrosion inhibitive pigment based on Neodymium (III)-Benzimidazole (C7H6N2). The chemical composition of the Neodymium-Benzimidazole pigment (Nd-Bi) was investigated by Fourier transform infrared (FT-IR) (spectroscopy) and X-ray photoelectron spectroscopy (XPS). The XPS and FT-IR results indicated strong chelation between Nd-Bi in the hybrid pigment. The ICP and UV–Vis analyses results reflected high release capability of inorganic and organic parts of the pigment in 3.5% NaCl solution and reached to the maximum concentration of 475 mg/L. Also the thermogravimetry analysis (TGA/DTG) results confirmed the chelation between the organic and inorganic parts of the Nd-Bi hybrid pigment. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results revealed that the Nd-Bi hybrid pigment addition to the saline solution yielded the maximum corrosion inhibition efficiency of 83.6% and showed mixed type corrosion inhibitor response. The corrosion resistance of mild steel in the NaCl solution inhibited by 1 g/l Nd-Bi hybrid pigment extract was 9 times greater than the uninhibited steel sample, reflecting the precipitation of a protective film whose composition was analyzed by using scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) analysis, XPS and contact angle measurements. The obtained results from surface characterizations confirmed the formation of a protective film by organic and inorganic parts of Nd-Bi pigment over the mild steel surface.