Adsorption and Inhibitive Properties of Camellia Sinensis for Mild Steel in 0.5M HCl and 0.8M H2SO4

Abstract

The effect of Camellia Sinensis (green tea) extract as a ‘green’ inhibitor on mild steel corrosion in 0.5M HCl and 0.8M H2SO4 was studied at ambient temperature. Weight loss/corrosion rate and potential measurement techniques were used for the experimental work. The results were further analyzed using the two-factor ANOVA. Potential measurement was performed using a digital voltmeter and a saturated calomel reference electrode. Results obtained showed effective corrosion-inhibition of the extract on the mild steel test-specimens in the different concentrations of HCl and H2SO4 used. There was increasing inhibition performance with increasing concentration of inhibitor. In 0.5M HCl, 100% green tea gave the optimal performance with weight loss and corrosion rate of 246mg and 0.63 mm/yr respectively. A similar result was observed in 0.8M H2SO4 where 100% green tea gave the best results of 1226 mg weight loss and 3 mm/yr corrosion rate. ANOVA test confirmed the results at 95% confidence, and further showed that concentration of green tea extract had greater effect on potential and weight loss measurements. The Gibb’s free adsorption energy signified physisorption in HCl and chemisorption in H2SO4 as the adsorption mechanism of plant extract molecules on the metal surface