The role of organic acid pretreatment in the efficient separation of hemicellulose has been demonstrated. However, the sugar-rich hydrolysates generated during pretreatment remain underutilized. In this study, itaconic acid (IA) was used to pretreat poplar hemicellulose, resulting in efficient separation. Under optimized conditions (5.0% acid concentration, 160 °C, 60 min), the xylose separation yield of the hydrolysate reached 82.21%. Adjusting the ethanol concentration of the aqueous solution resulted in a xylose extraction efficiency of 71.61% for the precipitated hemicellulose. Structural analysis revealed that the glycosidic bonds in hemicellulose were effectively cleaved, while the xylose branches were partially retained. Catalytic degradation mechanism studies indicated that IA suppressed xylose dehydration by forming ester and hydrogen bonds between its carboxylic groups and the hydroxyl groups of hemicellulose. Kinetic analysis showed that the activation energy for xylose degradation (91.98 kJ·mol −1 ) was significantly higher than that for hemicellulose hydrolysis (51.58 kJ·mol −1 ). It indicates that IA pretreatment promoted hemicellulose hydrolysis and effectively inhibited further xylose degradation. The conjugated structure of IA—comprising a carbon–carbon double bond and a carbonyl group—facilitated proton ionization and protected the xylose structure. These findings establish a novel strategy for efficient hemicellulose separation and for constructing sugar platforms enriched with xylose through organic acid pretreatment. • 82.21% of hemicellulose was separated by itaconic acid pretreatment. • The xylose concentration in the hydrolysate was 9.68 g/L, with a content of 81.14%. • The activation energy for xylose degradation is higher than that for xylan hydrolysis. • The dehydration of xylose is inhibited by the combination of itaconic acid and xylose.
Pang et al. (Fri,) studied this question.