Enhancement of rotary evaporation on the purification of poplar prehydrolysis liquor and preparation of xylo-oligosaccharide

Purification is an important approach to improve the added value utilization of xylo-oligosaccharides with 2–4 degree of polymerization (XOSDP 2–4) in pre-hydrolysis liquor (PHL). In order to improve the purification efficiency of PHL, rotary evaporation was explored to promote the inhibitor removal in poplar PHL. Influence of rotary evaporation on the composition and properties of PHL were investigated. After evaporation-Ca(OH)2-AC purification, the xylo-oligosaccharide in the purified PHL could be used to prepare XOSDP2−4 by enzymolysis of xylanase. The results showed that there was no loss of the total xylose/xylo-oligosaccharides during the rotary evaporation process, and evaporation also promoted the removal of lignin from PHL during the subsequent Ca(OH)2 and activated carbon (AC) treatment process, and the lignin removal increased from 57.80 % to 71.91 %. Furthermore, the furfural and acetic acids in PHL were separated and removed by condensation with the yields of 90.84 % and 23.63 %, respectively. 63.75 % of the XOSDP 2–4 yield was obtained after rotary evaporation-Ca(OH)2-AC purification and enzymolysis of xylanase based on the total xylose/xylo-oligosaccharides of the purified PHL with an increase of 25.12 % compared to the Ca(OH)2-AC purified PHL.