Microwave-assisted hydrothermal hydrolysis of cellobiose and effects of additions of halide salts

Abstract

Microwave irradiation was compared with induction heating for hydrothermal hydrolysis of cellobiose. Microwave heating improved glucose selectivity and resulted in a pH of the hydrolyzates that was ⩽0.57 units lower than those from conventional heating, which suggests that fewer side-reactions occurred. Halide salts of alkali and alkali earth metals improved microwave-assisted hydrothermal saccharification of cellobiose at lower reaction severity by around 0.3 of logR(0). NaCl addition of ⩾10mM reduced the required microwave output to 58.6-66.2% as compared to conventional microwave-hydrothermal hydrolysis without halide salts. Kinetic analyses revealed that the addition of salt increased the hydrolysis rate by increasing the frequency factor of the reaction. The results showed that microwave irradiation in the presence of microwave-absorbing salts is effective for hydrothermal hydrolysis of carbohydrates.