Corrosion inhibition and adsorption studies by Pogostemonquadrifolius methanolic stem extract (PQMSE) on mild steel in 1M HCL

Abstract

Pogostemon quadrifolius methanolic stem extract (PQMSE) has been investigated as non toxic green corrosion inhibitor for mild steel in 1 M HCl. Corrosion rates were evaluated at 303 K, 313 K and 323 K by weight loss method at varying inhibitor concentrations. Using electrochemical impedence spectroscopy (EIS) and polarisation techniques, corrosion studies were done at 303 K in various inhibitor concentrations. Adsorption studies were also conducted to study the mechanism of corrosion inhibition. Scanning electron microscopy (SEM) and Fourier – transform infrared (FT-IR) spectroscopy were used to study the surface morphology of mild steel. Electrochemical studies reveal that PQMSE exhibit excellent corrosion inhibition efficiency and it function as a mixed type of inhibitor at 303 K. The surface interaction of PQMSE on mild steel in 1 M HCl was obeying Langmiur adsorption isotherm at all studied temperatures.