Efficient extraction and recovery of xylan and lignin from rice straw using a flow-through hydrothermal system

Two-Stage Fractionation of Sugarcane Bagasse by a Flow-through Hydrothermal/Ethanosolv Process

“…The efficiency of the fractionation process in terms of the removal, recovery, and yield of hemicellulose and lignin achieved in our study and in previous works with pretreatment of different biomasses using the flow-through concept is summarized in Table . The hemicellulose removal, lignin removal, and lignin yield obtained from this study using two-stage fractionation by hydrothermal treatment with acid supplementation and the subsequent ethanosolv process using a flow-through reactor were comparable to those previously reported using bagasse and other raw material sources (rice straw, corn stover, poplar wood, softwood, and Miscanthus giganteus) in organic and aqueous systems, which led to varying process efficiencies in a range of 27.7–100.0%. ,− ,− Compared to the one-stage process, the two-stage flow-through fractionation by hydrothermal and ethanol processes in this study offered high efficiency and selectivity for sugarcane fractionation and facilitated recoveries of hemicellulose and lignin along with the cellulose-enriched fraction under the optimized experimental conditions in the presence of the acid promoter in the first hydrothermal step.…”

“…Increasing the temperature in the range from 150 to 190 °C under conditions with no supplemented acid resulted in an increase in the total hemicellulose and cellulose fractions. This could be related to an increase in the autoionization of water to acidic hydronium ions (H 3 O + ) under harsher conditions, which promoted the release of acetic acid and uronic acid from the hemicellulose structure . This led to more breakdown of the biomass structure and release of the hydrolyzed sugar products to the liquid phase.…”

“…This could be related to an increase in the autoionization of water to acidic hydronium ions (H 3 O + ) under harsher conditions, which promoted the release of acetic acid and uronic acid from the hemicellulose structure. 16 This led to more breakdown of the biomass structure and release of the hydrolyzed sugar products to the liquid phase. According to these results, the efficiency of hemicellulose and removal in the solid phase including the yield and recovery of biomass components in the liquid fraction is summarized in Table 1.…”

“…A flow-through process is a conceptual configuration where the liquid solvent or water flows through the solid biomass in the extractor unit under conditions with controlled temperature, pressure, and liquid hourly space velocity (LHSV). Advantages of the flow-through process compared to the batch process include the following: no need for an additional step for solid/liquid separation, an increase in mass and heat transfer, improvement of hemicellulose and lignin removals, reduction of undesirable byproducts from sugar degradation or extracted solvents, and allowance of a more straightforward scaling up process based on the control of LHSV and L/D aspect ratio. , For instance, the flow-through process, namely, the Lignol process (US patent 2013/0172628), can be applied for commercial production of biorefinery products based on using an aqueous-ethanol mixture with an acid catalyst for separation of cellulose with high purity . Until now, there have been very few reports on flow-through systems for biomass fractionation, mostly by one-step hydrothermal or organosolv processes. − However, the efficiency of biomass fractionation in previous works was still limited due to the solubility of hemicellulose and lignin fractions in different aqueous/solvent phases.…”

“…Advantages of the flow-through process compared to the batch process include the following: no need for an additional step for solid/liquid separation, an increase in mass and heat transfer, improvement of hemicellulose and lignin removals, reduction of undesirable byproducts from sugar degradation or extracted solvents, and allowance of a more straightforward scaling up process based on the control of LHSV and L/D aspect ratio. 16,17 For instance, the flow-through process, namely, the Lignol process (US patent 2013/0172628), can be applied for commercial production of biorefinery products based on using an aqueousethanol mixture with an acid catalyst for separation of cellulose with high purity. 18 Until now, there have been very few reports on flow-through systems for biomass fractionation, mostly by one-step hydrothermal or organosolv processes.…”