Enhanced Enzymatic Hydrolysis Of Sugar Beet Pulp By Aqueous Ammonia Pretreatment

Cellulosic ethanol, with the advantages of renewable resource, cleanliness and safety, is the mainstream direction of new energy development and has been obtained extensive attention from countries and enterprises around the world. Sugar beet pulp, byproducts derived from sugar beet industry, is deemed as the potential feedstocks for the cellulosic ethanol production. However the low enzymatic hydrolysis of cellulose severely restricted the development of cellulosic ethanol production. Hence various pretreatments were established and used in ethanol production.In this study, aqueous ammonia pretreatment of sugar beet pulp at low temperature were established. The cellulose conversions of sugar beet pulp were analyzed. The effects of the pretreatment on the chemical composition, physical structure, and cell wall morphology were discussed.The effects hydrochloric acid pretreatment, aqueous ammonia pretreatment, ammonium oxalate pretreatment and pectinase pretreatment on cellulose conversions of sugar beet pulp were compared. The optimal process of aqueous ammonia pretreatment of sugar beet pulp at low temperature was established. The effects of the pretreatment on the chemical composition, physical structure were discussed. And the changes of cell wall morphology were characterized by fluorescence microscopy, scanning electron microscopy, confocal laser scanning microscope in different level. The main conclusions are as follows:1. Aqueous ammonia pretreatment at low temperature was established. The cellulose conversion of sugar beet pulp could reach to 63.72%, which was 82.47% higher than that of raw material, under pretreatment condition of 10% aqueous ammonia, at 80℃, for 6h, with solid to liquid ratio of 1:20.2. The chemical compositions of sugar beet pulp were changed by aqueous ammonia pretreatmet, the linkage of lignin and hemicellulose was broken and 48.95% neutral detergent was degraded, yet the content of cellulose was increased.3. The porosity and specific surface area of sugar beet pulp were increased, which resulted in the exposure of crystalline cellulose and mechanical tissue of sugar beet pulp.4. The aqueous ammonia pretreatment destroyed cell wall of sugar beet pulp, enlarged the intercellular space and changed cell size. The lignin and hemicellulose were removed based on the analysis of fluorescence microscopy. The cellulose became rough and crushed based on the analysis of electron microscopy.