Fractionation of lignin and fermentable sugars from wheat straw using an alkaline hydrogen peroxide/pentanol biphasic pretreatment.

To breakthrough the delignification saturation point (DSP) of alkaline hydrogen peroxide (AHP) pretreatment, a biphasic AHP/pentanol (AHPP) pretreatment was proposed in this work. The temperature and H₂O₂ concentration were evaluated. Under the optimal conditions (110 °C, 2h, 4% H₂O₂), 70.73% of lignin was removed, which was increased by 11.65% than the traditional AHP pretreatment, indicating successful overcoming of the DSP by adding pentanol. 85.74% and 88.62% of glucan and xylan digestibility were achieved, respectively, which increased by 7.41% and 5.87% as compared to AHP pretreatment. Furthermore, the lignin extracted from the organic phase accounted for 38.51% of the delignification, and it had a low molecular weight, effectively preserving the β-O-4 bonds. Finally, satisfied pentanol recovery (77.91%) and delignification (57.19%) along with excellent glucan (76.11%) and xylan (77.52%) digestibility were reached after fourth recycling of AHPP pretreatment. Therefore, AHPP pretreatment was a promising method for biomass valorization within biorefinery concept.