Production of xylooligosaccharides by microwave-induced, organic acid-catalyzed hydrolysis of different xylan-type hemicelluloses: Optimization by response surface methodology

A feasible approach to produce xylooligosaccharides (XOS) using organic acids as catalysts by microwave-induced hydrolysis of different hemicelluloses was developed. The effects of different acids (oxalic acid, maleic acid, citric acid and sulfuric acid), acid concentration, reaction temperature and reaction time on the hemicelluloses hydrolysis were investigated. Results demonstrated that organic acid was more beneficial to the XOS production than the conventional sulfuric acid. Higher acid concentration, higher reaction temperature and longer reaction time accelerated the further depolymerization of XOS to form monosaccharide. Response surface methodology was employed to optimize the reaction conditions (temperature and time) for the production of XOS from beechwood xylan (BX), corncob hemicelluloses (CH) and recovered hemicelluloses from the industrial waste liquor of dissolving pulp (RH), respectively. The predicted highest XOS yields were achieved to 39.31% (126.54 °C-7.95 min), 27.29% (120.00 °C-0 min), 30.32% (122.63 °C-15.85 min), respectively, being close to the experimental value (39.42%, 27.46% and 30.89%) from BX, CH and RH, indicating the fitted models of XOS yield were in good agreement with the experimental results.