Evaluation of bio-hydrogen production using rice straw hydrolysate extracted by acid and alkali hydrolysis

This study was conducted to investigate the properties of hydrolysates obtained from acid and alkali hydrolysis and to evaluate the feasibility of employing them for bio-hydrogen production. High sugar concentrations of 16.8 g/L and 13.3 g/L were present in 0.5% and 1.0% H2SO4 hydrolysates, respectively. However, H2SO4 hydrolysis resulted in large amounts of short-chain fatty acids (SCFAs) and furan derivatives, which were removed by detoxification. In bio-hydrogen production, 1.0% H2SO4 hydrolysate showed a 55.6 mL of highest hydrogen production and 1.14 mol-H2/mol-hexose equivalentadded of hydrogen yield. In control and 1.0% NaOH hydrolysate, 29.7 mL and 36.9 mL of hydrogen were pro-duced, respectively. Interestingly, relatively high acetate and butyrate production resulted in lactate reduction. Also, NH4OH hydrolysate produced less than 10 mL of hydrogen. Thus, these results indicate that hydrogen production and metabolite distribution can vary depending on the sugars and by-product composition in the hydrolysate. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.