STATISTICAL MODELLING AND OPTIMIZATION OF THE CONCENTRATION OF BIO-ETHANOL FROM WASTE PEELS OF MANIHOTESCULENTA CRANTZ USING RESPONSE SURFACE METHODOLOGY

Abstract

In this study, the optimization of the concentration of bio-ethanol from waste peels of Manihotesculenta Crantz (cassava) was carried out. The acid hydrolysis process was optimized using Response Surface Methodology (RSM). Central Composite Design (CCD) was employed to study the effect of hydrolysis temperature, pH, and acid concentration and also, for optimization of the bio-ethanol concentration from the peels of Manihotesculenta C. The anaerobic fermentation process was carried at room temperature (≈300C) for four days. Prior to this, the fermentation media was prepared by culturing yeast to ferment the sugar rich liquid. A quadratic statistical model was developed for the acid hydrolysis process and then validated. The model gave a significant p-value < 0.05 and also showed an insignificant lack of fit. The model predicted that at optimum acid concentration of 1.2 % v/v, temperature of 131.8 0C and pH of 5.3, a maximum bio-ethanol concentration of 24.48 g/L should be obtained. The prediction of the model was validated by a triplicate set of experiments carried out at the predicted optimum parameters which yielded an average value of 24.41 g/L for the bio-ethanol concentration. The results obtained indicate the viability of Manihotesculenta Crantz peels as a bio-fuel feedstock and corroborates the efficiency of CCD in determining the optimum values of the process parameters for the acid hydrolysis step of the bio-ethanol production process. Keywords: Hydrolysis, bio-ethanol, optimization, Response Surface Methodology, model