ELECTROCHEMICAL AND QUANTUM CHEMICAL ANALYSIS OF THE CORROSION OF MILD STEEL IN THE CRUDE LEAF EXTRACTS OF Cnidoscolus aconitifolius IN HCl MEDIUM
B. U. UGI *
Department of Chemical Sciences, Cross River University of Technology, P.M.B. 1123 Calabar, Nigeria
I. E. UWAH
Department of Pure and Applied Chemistry, University of Calabar, P.M.B. 1115 Calabar, Nigeria
P. C. OKAFOR
Department of Pure and Applied Chemistry, University of Calabar, P.M.B. 1115 Calabar, Nigeria
M. E. OBETEN
Department of Chemical Sciences, Cross River University of Technology, P.M.B. 1123 Calabar, Nigeria
EKERETE JACKSON
Department of Chemistry, University of Uyo, P.M.B. 1017, Uyo, Akwa Ibom State, Nigeria
*Author to whom correspondence should be addressed.
Abstract
Alkaloid and nonalkaloids extracts of Cnidoscolus aconitifolius stem is reported as corrosion inhibitor of mild steel in 1 M HCl. Conventional weight loss measurements, electrochemical and polarization techniques are employed to study the effect on mild steel corrosion in HCl solutions. The weight loss result revealed that both plant extracts are excellent corrosion inhibitors. Electrochemical polarization data revealed mixed mode of inhibition. The increase in % IE with change in concentration of the extracts suggests the strong adsorption of active molecules leading to the formation of a protective layer on the mild steel surface. It was found that adsorption of both stem extracts followed Langmuir adsorption.
Keywords: Weight loss, langmuir isotherm, activation energy, corrosion current density, inhibition efficiency, EIS