Investigation of organic solvents’ effects on Kenaf (Hibiscus cannabinus L.) biomass conversion in subcritical water

Kenaf biomass was hydrolyzed under subcritical water conditions in the presence of various organic solvents. The solvents tested were tetrahydrofuran (THF), acetone, xylene (mixed isomers) and methanol. The organic compounds released into hydrolysates, total organic contents, water-soluble total phenols, and the molecular weight distributions of the polysaccharides in the hydrolysates, solid residues leftover after hydrolysis and gaseous products formed during the solubilization process were determined. The results showed that organic solvents significantly enhanced the dissolution of kenaf biomass (methanol < (omp)xylene ≤ acetone ~ tetrahydrofuran). The hydrolysis percentage was found to be between 75-82% depending on the type of the solvent. Hydrolysis yield and total organic carbons released into hydrolysates highly differed when the solubilization process was performed under carbon dioxide pressure and this effect considerably varied based on the type of solvent used in hydrolysis process. The main gas product formed during hydrolysis process was carbon dioxide with ~80% composition. Morphological measurements of the solid biomass residues left after hydrolysis showed substantial degradations with increasing number of pores on the biomass surfaces.