Pretreatment of vine shoot biomass by choline chloride based 2 deep eutectic solvents to promote biomass fractionation and en-3 hance sugar production

Abstract

Vine shoots hold promise as a biomass source for fermentable sugars with efficient frac-11 tionation and conversion processes. The study explores vine shoots as a biomass source for ferment-12 able sugars through pretreatment with two deep eutectic solvents mixtures; choline chloride: lactic 13 acid 1:5 (ChCl:LA) and choline chloride: ethylene glycol 1:2 (ChCl:EG). Pretreatment conditions, 14 such as temperature-time, solid/liquid ratio, and biomass particle size, were studied. Chemical com-15 position, recovery yields, delignification extent, and carbohydrate conversion were evaluated, in-16 cluding the influence of washing solvents. Temperature and particle size notably affected hemicel-17 lulose and lignin dissolution, especially with ChCl:LA. Pretreatment yielded enriched-cellulose sub-18 strates, with high carbohydrate conversion rates up to 75.2% for cellulose and 99.9% for xylan with 19 ChCl:LA, and 54.6% for cellulose and 60.2% for xylan with ChCl:EG. A 50% acetone:water mixture 20 increased delignification ratios to 31.5%. Results underscore the potential of this pretreatment for 21 vine shoot fractionation, particularly at 30% solids load, while acknowledging the need for further 22 process enhancement