Title
Challenges in understanding the simultaneous aqueous extraction and hydrolysis of spruce hemicelluloses
Authors
JUSSI V. RISSANEN HENRIK GRENMAN CHUNLIN XU JENS KROGELL STEFAN WILLFOR DMITRY YU. MURZIN and TAPIO SALMI

Received March 27, 2014
Published Volume 49 Issue 5-6 May-June
Keywords hemicellulose, aqueous extraction, hydrolysis

Abstract
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 °C 170 °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.