EFFECTIVE ALKALINE PEROXIDE OXIDATION PRETREATMENT OF SHEA TREE SAWDUST FOR THE PRODUCTION OF BIOFUELS: KINETICS OF DELIGNIFICATION AND ENZYMATIC CONVERSION TO SUGAR AND SUBSEQUENT PRODUCTION OF ETHANOL BY FERMENTATION USING Saccharomyces cerevisiae

Abstract

Shea tree sawdust delignification kinetic data during alkaline peroxide pretreatment were investigated at temperatures of 120 °C, 135 °C, and 150 °C. The activation energy during delignification was 76.4 kJ/mol and the Arrhenius constant was calculated as 8.4 x 106 per min. The reducing sugar yield for the treated to the untreated biomass was about 22-fold. Enzymatic hydrolysis conditions studied were; time (72 h and 96 h), substrate concentration (20, 30, 40, and 50 g/L), and enzyme loadings (10, 25, 40, 50 FPU/g dry biomass), which showed the optimum conditions of 96 h, 40 g/L, and 25 FPU/g dry biomass at 45 °C hydrolysis temperature. At the optimized enzymatic hydrolysis conditions, the reducing sugar yield was 416.32 mg equivalent glucose/g treated dry biomass. After 96 h fermentation of treated biomass, the ethanol obtained at 2% effective cellulose loading was 12.73 g/L. Alkaline peroxide oxidation pretreatment and subsequent enzymatic hydrolysis improved the ethanol yield of the biomass.