Studies of Monosaccharide Production through Lignocellulosic Waste Hydrolysis Using Double Acids

A new technology called double acid hydrolysis of lignocellulosic waste for bioethanol production has been proposed via combination of hydrochloric acid and sulfuric acid. Double acid hydrolysis is characterized with several advantages, i.e., low process energy consumption, high monosaccharide concentration and yield, inner recycle of wastewater, and no interference to ethanol distillation from crystal calcium sulfate evolving. On the basis of this hydrolysis technology, industrialization of bioethanol production is promising in terms of both economical and environmental aspects. The effects of reaction temperature and time, acid concentration, and the ratio of liquid to solid biomass (US) on monosaccharide concentration and yield were investigated and the optimum reaction conditions were determined as follows. The temperatures for the first stage hydrolysis and the second stage hydrolysis are 120 and 165 degrees C, respectively. The time for the first stage hydrolysis and the second stage hydrolysis is 25 and 15 min, respectively. Acid concentration is 1 wt %, and US is 8. Under these conditions, the concentration of xylose and glucose can attain values of 34.47 and 40.51 mg/mL, respectively, and the total fermentable monosaccharide concentration and yield can attain 74.98 mg/mL and 76.55%, respectively.