Kinetics of cotton cellulose hydrolysis using concentrated acid and fermentative hydrogen production from hydrolysate

The kinetics of cotton cellulose hydrolysis using concentrated sulfuric acid and the performance of fermentative hydrogen production from the hydrolysate in the batch system was carried out in this study. Effects of sulfuric acid concentrations, cotton cellulose concentrations and operating temperatures on the cotton cellulose hydrolysis were investigated. It was found that cotton cellulose can dissolve completely in sulfuric acid concentration above 55% (by volume) at room temperature. The reduced sugar yields were varied from 64.3 to 73.9% (g R-sugar/g cotton cellulose) with the initial cotton cellulose concentrations of 30–70 g/L at a temperature of 40 °C.The reduced sugar concentrations and the initial pH of biohydrogen production were investigated at 37 °C. It was found that the optimal values of the hydrogen yield and substrate utilization were 0.95 mol H2/mol R-sugar and 98% with an initial pH of 8.2, when substrate concentration was fixed at 20 g R-sugar/L. The maximum hydrogen yield was 0.99 mol H2/mol R-sugar at a substrate concentration of 15 g R-sugar/L. Using the Gompertz Equation Model simulation, the maximum hydrogen production rate was 253 mL H2/h/L at a substrate of 30 g/L and initial pH of 8.4.