Poplar hemicellulose

Cellulose-, hemicellulose- and lignin-rich biomass (e.g., forest trees, typically eucalyptus, poplar and similar fast-growing trees). 

Steam-aqueous fractionation of poplar wood was performed at the University of Sherbrooke, Canada using a continuous Stake II unit. This treatment led to solubilization, afier washing, of 30% of the biomass into a hemicellulose-rich aqueous solution, which contained 32,1% of solutes of the elemental formula CH1.35O0.67-These solutes were mostly oligomeric pentosan and a small amount of dissolved lignin. 

Glucuronoxylan (15-30%) is the major hemicellulose of hardwoods such as birch, eucalyptus and poplar/aspen. It is similar to grass xylan, but lacks the arabinofuranosyl decoration (Figure 4.44). 

In ARP pretreatment of hybrid poplar, deUgnification is increased with the treatment severity, but xylan removal occurs only to a certain extent. Increase of temperature from 175 to 195 °C in ARP does not affect xylan/lignin removal in hybrid poplar, yet the glucan digestibility of treated solid is increased. This is caused by an increase of cellulase accessibility to cellulose created by breakage of certain bonds and reconfiguration of the components in hemicellulose-lignin matrix. Crystallinity index of hybrid poplar increases after the ARP treatment. It is primarily caused by the removal of amorphous components,... 

In SAA treatment, higher amount of hemicellulose is retained than in ARP because of lower severity of SAA. The SAA is more effective for LL hybrid poplar than HL hybrid poplar. 

The first smdy on PHA biosynthesis from the pentoses xylose and arabinose stemming from the hemicellulose fraction of poplar wood was done by Bertrand et al. (1990) with Pseudomonas pseudoflava ATCC 33668 (today known as... 

The homogeneous acylation of the hemicellulose is mostly carried out in the solvent iV,/V-dimethylformamide (DMF) in combination with LiCl. Hemicellulose extracted from poplar wood chips was acylated with various carboxylic acid chlorides in DMF/LiCl applying triethylamine and 4-N,N-dimethylaminopyridine (DMAP) as base and catalyst (J, Table 1). Depending on... 

Sun, RunCang Fang, J.M. Tomkinson, J. Hill, C.A.S. Esterification of hemicelluloses from poplar chips in homogeneous solution of N,N-dimethylformamide/Lithium chloride. J. Wood Chem, Technol 1999,19(4), 287-306. 

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