Synergistic Corrosion Inhibition Effects of Coptis Extract/Berberine and Thiourea on the Corrosion of Mild Steel in Carbon Dioxide Saturated Brine Solution

Abstract

The synergistic inhibition effects of the coptis extract (CP)/berberine (BB) and thiourea (TU) on the corrosion of mild steel in 3% NaCl solution saturated with CO2 at 60 °C was investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) methods. CP and BB act as moderate inhibitors, and inhibition efficiency of the former is higher than that of the latter. The adsorption of them obeys Langmuir adsorption isotherm. The inhibition performance was significantly improved by the combined use of them with TU, and obvious synergistic corrosion inhibition effect was achieved.