The aqueous extraction of hemicelluloses has gained an increasing interest with new emerging applications for hemicelluloses in the modern forest-based biorefinery concept. The extraction kinetics play a key role in their industrial utilization as both the reaction rate of the dissolution itself and the hydrolysis kinetics influence the recovery of the desired products. Pressurized hot water extraction of spruce sapwood was investigated in the temperature range 120 degrees C-170 degrees C using a large liquid-to-solid ratio in an intensified cascade reactor system. The results show a complex dependence of the final product on various parameters. A significant temperature dependence of the extraction rate was observed, albeit low influence of the changes in pH. Moreover, a clear dependence of the hydrolysis rate on the temperature and pH was observed. The molar mass of the extracted hemicelluloses was clearly influenced by the internal diffusion limitations, which are dependent on the chip size.
|Tidskrift||Cellulose Chemistry and Technology|
|Status||Publicerad - 2015|