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Bi-REX: biomass treatment method with green solvents

BiomassCelluloseChemical extractionDeep Eutectic Solvents (DES)ESTECHZero WasteZero Waste


It is an innovative and sustainable treatment for the recovery of high value biomass products, deriving from agro-industrial processing. It is based on a series of solubilizations and selective precipitations that use water, ethanol and eutectic solvents (DES) as solvents. DES are new eco-friendly solvents consisting of a hydrogen bonding acceptor and various hydrogen bonding donors. With a completely green process, which exploits agricultural biomass, it is therefore possible to obtain raw materials such as cellulose, lignin and silica, which can be used in countless production processes.

Technical features

The proposed process consists of the selective recovery of the biopolymer components and of the silica contained in the following biomasses: rice husk, rice straw, thistle and malt. The process is based on a series of selective precipitations that use water and eutectic solvents (DESs) as solvents which contain choline acetate ([Ch] OAc) as a hydrogen bonding acceptor (HBA), in combination with various bonding donors to hydrogen (HBD), such as glycolic acid (GA), diglycolic acid (DA), levulinic acid (LA) and imidazole (IM). The invention consists in treating the biomass with DES obtaining a precipitate enriched with cellulose and silica and a surnatant containing DES, hemicellulose and lignin. This last fraction can be further separated into lignin and hemicellulose. In principle, DES can be recovered and reused.

Possible Applications

  • Biomass recycling;
  • Extraction of high added value material such as cellulose, lignin hemicellulose and silica.


  • Increase in the degree of crystallinity of cellulose;
  • Separation of silica;
  • DES contain only the elements Carbon, Hydrogen, Oxygen and Nitrogen useful for industrial disposal (combustion);
  • DES halogen free;
  • DES recyclability (closed cycle process).