Efficient production of glucose by ozone-assisted acid hydrolysis of α-cellulose

Depolymerization of cellulose in lignocellulose into glucose is one of the most essential technologies for transforming lignocellulose biomass into fuels and other bio-based products. In this study, α-cellulose extracted from scutched flax tow was used as the raw material, and ozone pretreatment was used as an auxiliary process for acid hydrolysis to enhance the yield of glucose after depolymerization of α-cellulose. The ozone pretreatment experiment was conducted under conditions of an ozone concentration of 130 mg/L, pH 13.0, and a water pick-up value of 70% for 30 min-120 min, followed by acid hydrolysis treatment. Results showed that after ozone pretreatment, the glucose yield increased from 13.80% to 64.43%. SEM analysis revealed that the surface of α-cellulose treated with ozone exhibited obvious etching, and the content of carboxyl and carbonyl groups increased markedly. In addition, ozone pretreatment could significantly reduce the crystallinity, thermal degradation temperature, degree of polymerization, and molecular weight of α-cellulose. Hydrogen bonding analysis revealed that ozone pretreatment effectively disrupted the hydrogen bonding structure of α-cellulose, resulting in an increase in the content of free hydroxyl groups on the α-cellulose surface. Moreover, with the extension of ozone pretreatment time, the degree of oxidative depolymerization of α-cellulose further deepens. A reaction mechanism for ozone depolymerization of cellulose was proposed based on the observed structural and chemical changes.