Document Type : Regular Article
Department of Pure & Industrial Chemistry, Faculty of Physical Sciences, University of Calabar, P. M. B. 1115, Nigeria
Chemical/Petrochemical Engineering Department, Rivers State University, Port Harcourt-Nigeria
Alkaloid and Flavonoid extracts of Salvia Officinalis Leaves ( AESOL and FESOL) as eco-friendly corrosion inhibitors of 817M40T Mild Steel in 0.5 M Hydrochloric acid concentrated environment was carried out. Weight loss, Thermometric, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were employed. The corrosion rate values of the alkaloid and flavonoid were seen to be in the decrease from 1.6 – 0.01 and 1.6 – 0.1 while the inhibition efficiency values were in the increase from 79.7 % - 99.3 % and 75.1 % - 93.8 % for alkaloid and flavonoid fractions respectively at concentrations of 150 – 1000 ppm which defined the inhibitors a good inhibitors. A slight effect of temperature on the inhibition process was observed from the thermometric result as temperature was increased owing to strong agitation of heat. Electrochemical data showed that charge transfer resistance and inhibition efficiency were increasing while double layer capacitance and corrosion current density values were decreasing with concentration. A mixed type inhibition was recorded while adsorption process proved that the inhibitors were a monolayer type and physically adsorbed. Thermodynamic data revealed an inhibitor that is stabled, spontaneous, associative and endothermic in reaction.