ADSORPTION AND INHIBITIVE EFFECT OF Carica papaya AND Azadirachta indica EXTRACTS ON CORROSION OF ALUMINIUM IN HYDROCHLORIC ACID
Abstract:
The inhibition of aluminium metal from corrosion in 1.85M hydrochloric acid solutions by crude extract of Azadirachta indica and Carica papaya leaves was studied using gasometric technique. Aluminium coupons were immersed in test solutions of uninhibited 1.85 M HCl and those containing extract concentrations of 10%, 20%, 30%, 40% and 50% (v/v) at room temperature. The volume of hydrogen gas evolved as a result of the rate of reaction between aluminium coupons and the acid extracts was recorded. The inhibition efficiency of the extracts was determined and the adsorption isotherm of the process was estimated using four adsorption theories namely; Frumkin, Freundlich, Langmuir and Temkin. It was observed that the plant extract retarded the acid induced corrosion of aluminium and the volume of hydrogen gas evolved reduced with increasing extract concentration. The adsorption studies revealed that Langmuir isotherm is the best model for the adsorption of Azadirachta indica (R2 = 0.999) and Carica papaya (R2 = 1) on aluminium surface. This implied that the adsorption process between Azadirachta indica and Carica papaya extracts with aluminium metal obeys chemisorption.ORDER COMPLETE MATERIAL (CHAPTER 1-5)
