PHYTOCHEMICALS AND INHIBITIVE PROPERTIES OF CASHEW EXTRACT AS CORROSION INHIBITOR OF ALUMINIUM IN H2SO4 MEDIUM

Abstract

This work studied the phytochemicals and inhibitive properties of cashew extract as corrosion inhibitor of aluminium in H2SO4 medium. Qualitative and quantitative analyses of the cashew extract were carried out to identify and quantify the phytochemicals for the corrosion inhibition process. Thermometric and gravimetric techniques were employed in the study of corrosion inhibition of aluminium in H2SO4 medium. The inhibition efficiency of the cashew extract was modeled using Response Surface Methodology (RSM) of Design Expert Software 9. It was revealed that phytochemicals of alkaloids, cardiac glycosides, flavonoids, phenolics, phytates, saponins and tanins were present in the cashew extract at various degrees. The cashew extract is predominantly made of flavonoids (425.0mg/100g) followed by alkaloids (221.7mg/100g).Adsorption of the cashew extract on the Al surface obeyed physical adsorption mechanism. Thermometric and gravimetric techniques are in agreement of recording high inhibition efficiencies of 83.7% and 82.5% respectively. The phytochemicals of the cashew extract are good inhibitive agents for the corrosion control process. A quadratic model is adequate for the description of the inhibition efficiency of the cashew extract as a function of inhibitor concentration, temperature and time.