Advancing enzymatic hydrolysis efficiency of poplar sawdust through alkaline deep eutectic solvent pretreatment crafted from cetyltrimethylammonium bromide and ethanolamine

This work successfully developed an alkaline deep eutectic solvent (DES) composed of cetyltrimethylammonium bromide (CTAB) and ethanolamine (EA), and systematically evaluated its performance in the pretreatment of poplar sawdust (PS). The characterization of DES indicated an extensive hydrogen-bonding network and exceptional thermal resilience. Through optimization of key pretreatment parameters, the most effective pretreatment conditions were determined to be a molar ratio of CTAB to EA at 1:8, a temperature of 160 °C, and a time of 90   min. Under these optimized conditions, the DES demonstrated remarkable fractionation performance, achieving efficient delignification (64.2%) and substantial xylan extraction (92.4%). Ultimately, the enzymatic hydrolysis achieved an exceptional efficiency of 83.9%. Structural analyses unveiled that the pretreatment profoundly amplified substrate accessibility and elevated the crystallinity index of cellulose, while simultaneously achieving efficient cleavage of pivotal interunit linkages and aromatic frameworks embedded within lignin. The dominant mechanism underpinning enhanced efficiency centered on the disruption of lignin-driven supramolecular aggregation and the potentiation of intermolecular hydrogen bonding networks, thereby enabling a more thorough and effective disassembly of the lignocellulosic architecture. This remarkable enhancement in saccharification performance not only established a robust sugar platform for ethanol fermentation from PS but also delivered profound theoretical insights and critical technological advancements for the realization of high-value biorefinery systems leveraging other hardwood feedstocks.