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

Abstract

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, 2 h, 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.