Maximizing Populus tremula biomass conversion: synergistic pretreatment effects on sugars release and lignin recovery

The transition to a forest-based economy relies on sustainable alternatives that can efficiently convert renewable resources into chemical and material products. Sugar-centered wood fractionation processes, also called modern biorefineries, offer significant potential as a renewable precursor for the substitution of petrochemical derivatives. However, unlocking the full potential of advanced biorefineries requires optimized pretreatment strategies to valorize all biomass-side streams. This work evaluated the distinctive and connective applications of nitrogen explosive decompression (NED), protic ionic liquid (PIL), and alkaline pretreatments for the production of monosaccharides, oligosaccharides, and high value lignin from aspen (Populus tremula) biomass within a biorefinery context. Each pretreatment method uniquely influenced biomass fractionation, affecting the hemicellulose and cellulose dissolution, delignification, and the physicochemical properties of the remaining cellulose and lignin components. The findings indicate that PIL pretreatment alone yielded 56% monomeric sugars upon saccharification. Additionally, the combinatorial PIL-NED and Alkaline-NED pretreatment was superior for lignin removal, achieving 68% and 85% delignification while concurrently generating valuable side streams. Henceforth, integrated PIL-NED collaborative approach presents a considerable cost and efficiency advantage over conventional biorefinery pretreatments, offering a promising pathway for the co-production of monosaccharides and high-quality lignin.