Joint action of ultrasonic and Fe³⁺ to improve selectivity of acid hydrolysis for microcrystalline cellulose.

In this study, the combination of Fe(3+)/HCl and ultrasonic treatment was applied to selectively hydrolyze cellulose for the preparation of microcrystalline cellulose (MCC). It was found that the crystallinity and specific surface area of hydrocellulose samples were higher (78.92% and 2.23581 m(2)g(-1), respectively), compared with the method that only used Fe(3+)/HCl catalyst without ultrasonic treatment. Meanwhile, the hydrolysate can be extracted and reused for cellulose hydrolysis for three runs, which was effective in saving the dosage of chemicals and reducing the pollution of the environment without affecting the properties of hydrocellulose. Moreover, the increased concentration of total reducing sugar (TRS) after three runs may be used as a valuable source in biofuels production. The technology of cellulose hydrolysis, by retaining the crystalline region for MCC products while promoting hydrolysis of amorphous region for further utilization is of great novelty, which may prove valuable in converting biomass into chemicals and biofuels, environmentally and economically.