Solvent-Enabled Nonenyzmatic Sugar Production from Biomass for Chemical and Biological Upgrading

We recently reported a nonenzymatic biomass deconstruction process for producing carbohydrates using homogeneous mixtures of γ-valerolactone (GVL) and water as a solvent. A key step in this process is the separation of the GVL from the aqueous phase, enabling GVL recycling and the production of a concentrated aqueous carbohydrate solution. In this study, we demonstrate that phenolic solvents—sec-butylphenol, nonylphenol, and lignin-derived propyl guaiacol—are effective at separating GVL from the aqueous phase using only small amounts of solvent (0.5 g per g of the original water, GVL, and sugar hydrolysate). Furthermore, using nonylphenol, we produced a hydrolysate that supported robust growth and high yields of ethanol (0.49 g EtOH per g glucose) at an industrially relevant concentration (50.8 g L−1 EtOH). These results suggest that using phenolic solvents could be an interesting solution for separating and/or detoxifying aqueous carbohydrate solutions produced using GVL-based biomass deconstruction processes.