Hydrothermal alkaline treatment of lignocellulosic biomass for microcrystalline cellulose generation at subcritical water

• MCC was successfully prepared via removals of hemicellulose and lignin by employing hydrothermal alkaline treatment on the wood waste sawdust. • The increasing operating temperature and/or the prolonged treatment time may enhance the crystallinity index of product. • The combination of alkaline and hydrothermal treatments became a promising technology to isolate non-cellulosic constituents from woody biomass. Like lignocellulosic biomass, wood waste sawdust is rich in cellulose and can potentially be used as a source of microcrystalline cellulose (MCC) production via removal of hemicellulose and lignin constituents. Under hydrothermal alkaline treatment (100 to 140 °C), the breaking in the linkages of lignin and hemicellulose groups may happen, resulting in the solid residue, which is known as a cellulose-rich solid product. Results of FTIR analysis indicated that the removal of non-cellulosic constituents improved with increasing operating temperature and/or the prolonged treatment time. The XRD diffractogram pattern proved that improving the operating parameters (temperature and/or time) may also improve the crystallinity index of the solid product. On the contrary, the yield of the solid product decreases with increasing operating temperature and/or the prolonged treatment time.