| Abstract:The hydrothermal combined with acidic deep eutectic solvent (DES) treatments were used to pretreat Paulownia to obtain high xylose yield and enzymatic hydrolysis efficiency. Firstly, tartaric acid (TA) assisted hydrothermal pretreatment was utilized to treat Paulownia. The effects of temperature (120-160oC), time (15-120 min), and TA concentration (0-10 wt %) on xylose yield were examined. Result showed that the optimal hydrothermal pretreatment conditions were 140 °C, 60 min and 4 wt% TA, resulting in a maximum xylose yield of 80.5%. Subsequently, the hydrothermal residue was subjected to post-treatment with deep eutectic solvent (DES) composed of choline chloride and lactic acid operated at 90-150 oC for 2-8 h. The study revealed that the combined hydrothermal and DES treatments effectively removed hemicellulose and lignin, leading to increased crystallinity, surface roughness, specific surface area and accessibility of the treated Paulownia. The optimal DES post-treatment conditions were determined to be 130 °C for 6 h. Under the optimal treatment conditions, the removal rates of hemicellulose and lignin reached 100.0% and 89.7%, respectively, with a cellulose retention rate of 77.3% and an enzymatic hydrolysis efficiency of 85.2%, which was 4.6 times higher than that of raw paulownia wood. |