الفهرس | Only 14 pages are availabe for public view |
Abstract According to the Annual Report of Waste Management statistics in Egypt, issued 2013, Egypt has generated a total of 89.03 million tons of solid wastes. Agricultural wastes are widely available in Egypt and produced at an annual rate of more than 46.7 million tons /year . These wastes can be used normally as animal feed and/or fertilizers. Nevertheless, the majority of this value-added waste is left to be rot or burned in the open air after harvesting. Thus, utilization of this waste, which is a form of biomass, for industrial purposes and as a source of green energy stands in the center of environmental and economical viewpoints. Sugarcane Bagasse (SCB) is considered as one of the abundant types of agricultural wastes. SCB is a recalcitrant material, composed of cellulose, hemicellulose and lignin. It is organized in a complex network as recalcitrant lignocellulosic material, which could be successfully degraded using appropriate pretreatment technique into fermentable sugars, and eventually ethanol, i.e., green energy. The two-stages pretreatment process using freezing and alkaline agents efficiently separated the three main components of SCB. Freezing treatment played a preliminary role in breaking the linkages between components using acetate buffer solution (pH 4.6) for 2 h at -20°C and solid: liquid ratio of 1:25 (w/w) % . However, freezing pretreatment resulted in relatively low glucose yield and scarification ratio of 307.52 mg/g native SCB and 48.5%, respectively, where no total reducing sugars (TRS) was obtained. Therefore, alkaline pretreatment of the frozen-pretreated SCB was required. Further alkaline hydrogen peroxide (AHP) pretreatment was performed for the frozen-fractionated SCB at -20 °C and 2 h with assistance of Box–Behnken Design response surface methodology. The investigated key parameters were hydrogen iii peroxide concentration H2O2 (3, 5.5 and 8 % v/v), temperature (25, 42.5 and 60 °C) and pretreatment duration (1, 3 and 5 h). The results revealed that the statistical modelling was able to predict the response of glucose yield and TRS production with R2 = 0.8221 and 0.8814, respectively. After the optimization of (RSM), a model predicted the optimum values of glucose yield and TRS production of (886.507 mg/g native SCB and 1.44 mg/mL), respectively; confirmed by the experimental analysis (888.5 mg/g native SCB and 1.32 mg/mL), respectively. The coincided saccharification ratio was 97.5%. These results were obtained at H2O2 of 3 % (v/v), 56.93 °C and 1 h which were 2.88 and 2.01 times higher than that obtained from the freezing pretreatment for glucose yield and saccharification ratio respectively |