Depolymerization of microcrystalline cellulose by the combination of ultrasound and Fenton reagent

• Fenton reagent was efficient in decreasing the crystallinity of MCC.
• Ultrasound was efficient in decreasing the degree of polymerization of MCC.
• Degree of polymerization greatly affected the enzymatic hydrolysis rate of MCC.
• The highest yield of reducing sugar was obtained from the U/F-pretreated MCC.

In this study, the combined use of Fenton reagent and ultrasound to the pretreatment of microcrystalline cellulose (MCC) for subsequent enzyme hydrolysis was investigated. The morphological analysis showed that the aspect ratio of MCC was greatly reduced after pretreatment. The X-ray diffraction (XRD) and degree of polymerization (DP) analyses showed that Fenton reagent was more efficient in decreasing the crystallinity of MCC while ultrasound was more efficient in decreasing the DP of MCC. The combination of Fenton reaction and ultrasound, which produced the lowest crystallinity (84.8 ± 0.2%) and DP (124.7 ± 0.6) of MCC and the highest yield of reducing sugar (22.9 ± 0.3 g/100 g), provides a promising pretreatment process for MCC depolymerization.