Research on the Dissolution of Pentosans during Eucalyptus Hydrolysate Pretreatment

Abstract

Hydrolysate pretreatment (HP) uses hot water pre-hydrolysis liquor (HWPL) as partial or full pretreatment medium for biomass. Pentosan dissolution during Eucalyptus HP was studied under holding times between 0 min and 160 min, holding temperatures between 150 °C and 190 °C, a hot water pre-hydrolysate ratio (HWPR) from 20% to 100%, and a fixed liquid to wood ratio of 1:6. Both the pentosan removals in the hydrolysate pretreated solid (HPS) and the hydrolysate pretreatment liquor (HPL) pento-saccharides contents were determined and compared with those of hot water pre-hydrolysis (HWP). When compared to HWP, the HP enhanced pentosan removal from the solid phase, and enriched the saccharides or promoted the in-situ conversion of saccharides into other chemicals in the liquid phase. Pentosan removal in the HPS increased when holding time and temperature were increased. Increasing holding time first increased the pento-saccharide content in the HPL, and then decreased it after reaching the maximum. Elevating the holding temperature increased the pento-saccharide content in the HPL, except for arabino-oligosaccharide. Different HWPR had varying influences on pentosan removal in the HPS and on the saccharides concentration in the HPL. When controlled, HP positively influenced hemicellulose removal from biomass, and increased utilization value of the liquid phase obtained post pretreatment. Dalian, Liaoning, 116034 China; b: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640; * Corresponding authors: 286911185@qq.com; zhoujh@dlpu.edu.cn Keywords INTRODUCTIONFossil fuel resources have been the main energy and chemical source for humans since the Industrial Revolution. However, the availability of fossil fuel resources on earth is limited. Biomass resources are renewable, in contrast to fossil fuel resources, and sustainable management can be obtained in the long term if the biomass is properly utilized (Amidon and Liu 2009). Plant biomass is mainly composed of cellulose, hemicellulose, and lignin (Agbor et al. 2011). Cellulose is a highly crystallized polymer with glucose as the monomer. Hemicellulose is polymerized from several different monosaccharides such as pentoses (arabinose, xylose, etc.) and hexoses (galactose, glucose, mannose, etc.). Lignin is a three-dimensional natural polymer with building blocks of phenylpropane units joined together through ether bonds and carbon-carbon bonds. The existence of complex linkages, caused by physical or chemical action between those three components, makes plant biomass resistant to the production of chemicals or fuel directly (Yedro et al. 2015). PEER-REVIEWED ARTICLEbioresources.com Ma et al. (2017). "Dissolution of pentosans," BioResources 12(2), 3677-3694. 3678Traditionally, hemicellulose is partly dissolved in the pulping effluent during the pulping process and burned to produce heat together with lignin, which dramatically hinders its utilization. In recent years, scientists worldwide have paid increasing a...

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