Studies on Thermal Stability, Shelf Life and Electrochemical Measurement of Methanol Extract of Air Dried Alchornea Laxiflora Leaves in Corrosion Prevention

Abstract

The aim of this study was to determine the thermal stability and shelf life of the extract together with the influence of extract concentration, temperature and pH variation of the acidic medium on the inhibition efficiency using 1.0 M Sodium hydroxide. The dried plant samples were ground, sieved using 0.25µm and then extracted with methanol using maceration method. The phytochemical constituents were analyzed using appropriate methods. The phytochemicals detected were: Alkaloid, saponin, flavnoid, tannin, terpenoid, steroid and cardiac glycoside. Weight loss experiment was performed to ascertain the stability and shelf life of the extract at different storage temperature and time respectively while polarization experiment was used to study the behaviour of the extract on mild steel corrosion at varying concentration of the extract, pH and temperature of the acidic media. It was found that the stability of the extract inhibition efficiency was affected by the mode of storage and the inhibition efficiency decreases with increase in storage temperature of the extract. The life span of the extract was found to be 60 days from its production stage, after this, there was reduction in the inhibition efficiency of the extract. Moreso, the corrosion rate of the mild steel in 1.0 M HCl, monitored by electrochemical measurement revealed that the corrosion rate decreases with increase in the pH, decrease in temperature and increase in concentration of the extract in the acidic solution. Keywords: Phytochemicals, Storage Temperature, Shelf Life, Solution pH 1.