Sequential extraction of hemicelluloses and lignin for wood fractionation using acid hydrotrope at mild conditions

Sequential fractionation (SF) of woody biomass using acid hydrotrope p-toluenesulfonic acid (p-TsOH) as reaction medium was investigated. Hemicellulosic sugars, lignin, and cellulose-rich solid were harvested as the main products from the stepwise deconstruction of biomass as results of hemicelluloses hydrolysis and subsequent lignin dissolution. The first step of SF employed 2wt% p-TsOH, far below the minimum hydrotrope concentration (MHC) of 11.5wt%, and reached 23.5 % of biomass dissolution with 55.1 % removal of xylan from wood at 120 °C for 2 h. The second step of SF was characterized with mild conditions of 100 °C, 40wt% p-TsOH, and one hour, and achieved 83 % lignin dissolution with well-preserved structure. The obtained cellulose-rich solid from SF showed a high crystallinity index of 73.3 % and a complete recovery of glucan. This means excellent performance of SF for sustainable bio-refining.