Optimization and inhibitive effects of Sweet Potato Leaf Extract (SPLE) on mild steel

Abstract

Weight loss and electrochemical techniques were used to evaluate the inhibition efficiency of sweet potato leaf extracts (SPLE) as inhibitor on mild steel in phosphoric acid. Box Behnken design was used to examine the interactions of these variables: acid concentration (0.5–1.5 M); time (5–10 days); inhibitor concentrations (0.3–0.9 g/L) and temperature (30–60 °C) respectively. Polarization and Electrochemical impedance and were used to measure the inhibition efficiency. The surface morphology of coupons was analysed using Scanning Electron Microscope (SEM). The experimental data was statistically analysed and regression equation was generated for inhibition efficiency. The weight loss measurement revealed that extract acts as an inhibitor for mild steel in phosphoric acid and decreases rate of corrosion. The results of inhibition efficiency derived from polarization studies and impedance analyses agree. The validated experiment's coupon created a better protected inhibitive layer than coupon of the best process level as observed from experimental design, according to SEM analysis. It can be concluded that the extract operated as an inhibitor by producing outer film on the surface of mild steel