Research On Sweet Sorghum Straw Hydrolysis

Sweet sorghum is known as high-energy plant, and has a good prospect in ensuring food security and production of fuel ethanol. Currently, production of the fermentable sugar from sweet sorghum straw is the global interest. So it is necessary to research on sweet sorghum straw hydrolysis.First, pretreatment of sweet sorghum stalk using dilute acid was investigated under mild conditions. Process parameters investigated included reactor temperature, reaction time and acid concentration. Xylose concentration, xylose yield and decomposition products concentration were measured. The highest yield of xylose 77.5% was achieved under optimum conditions. The optimal conditions selected were 0.75%(w/w) acid concentration, 140℃and 10min. Using theses conditions,23.9g/L of xylose concentration,0.98g/L of furfural and 2.52g/L of acetic acid were obtained. The decomposition products concentration is low.In this work, hydrolysis of sweet sorghum bagasse (SSB) residue using dilute acid was investigated. The SSB residue was from pretreatment. The effects of dilute acid hydrolysis were assessed by glucose yield and decomposition products concentration. The highest yield of glucose 70.10% was found at the temperature of 170℃, acid concentration of 1.0% (w/w), and a reaction time of 10min. Meanwhile,0.99g/L of acetic acid,0.22g/L of furfural,0.73g/L of HMF,1.60g/L of LA were obtained under these conditions, which concluded that the decomposition of glucose was slight and confirmed the selectivity of the dilute acid hydrolysis of the SSB residue. The present work aims to take full advantage of the SSB residue and obtain glucose solutions with low concentration of growth inhibitors.Compared with the dilute hydrolysis of cellulose, we also studied the effects of enzymatic hydrolysis. Process parameters included enzyme dosage, the proportion of two enzymes dosage, temperature and pH. The optimal conditions were found at enzyme dosage 75U/g, the proportion of two enzymes dosage of 3:1, temperature of 50℃, pH of 4.5, liquid-solid ratio of 10:1.The enzymatic hydrolysis yield was 85.31% and the glucose concentration was 61.59g/L. The study also showed that the glucose has strong inhibition on enzymatic hydrolysis. In addition, the enzyme catalyst was added in batches, increasing the ultimate enzymatic hydrolysis yield, compared with adding the enzyme at once.This paper also established the kinetic model of dilute acid hydrolysis of sweet sorghum straw. The hydrolysis and degradation rate were as follows:...