Design of a hybrid organosolv-ionosolv lignin fractionation method and lignin-like polymer synthesis for value added applications

Biofuel technology has been introduced to reduce the reliance on fossil fuels. It is also superior for addressing environmental issues, such as greenhouse gas (GHG) emissions. Biofuel production from lignocellulosic biomass has been attracting attention due to the high abundance of the feedstock and the incredible GHG emission reduction associated with the production process. Ionic liquid pretreament, the ionoSolv process, and organosolv pretreatment are well-known for their selective fractionation performance. The ionoSolv process is able to generate a highly digestible cellulose fraction and the organosolv process is famous for producing high quality lignin as the side product, where the lignin generated is suitable for value-added applications. Here, a hybrid pretreament process has been developed based on these two processes, where two protic ionic liquids and three organic solvents were the selected solvents. The new process has been tested on three classes of feedstocks, miscanthus, pine and agricultural residues. The pretreatment effectiveness was determined by enzymatic saccharification and compositional analysis. The isolated lignin fraction was subjected to HSQC and GPC analysis. For miscanthus, ethanol/butanol-IL process was able to produce a highly digestible pulp with a glucose yield of up to 85%, 10% higher than the standard ionoSolv pulp, due to more profound lignin removal for the hybrid process. The process maintained its functionality with a range of IL acidities, 1.00 to 1.02 (acid/base) and up to 50% wt biomass loading. Similar glucose yield increases were observed for pine, rice husk and bagasse. For the process of two straws, additional hemicellulose releases were detected in enzymatic hydrolysis while the level of glucose yields remained the same as for the ionoSolv ones. HSQC NMR of the lignin indicated that α-alkoxylation took place during ethanol/butanol-IL fractionation, inhibiting lignin condensation. Three major monolignols were synthesised and radical polymerisation induced by horseradish peroxidases was conducted for the monolignols synthesised. The lignin-like polymer was analysed by GPC.Open Acces