EGEE 439
Alternative Fuels from Biomass Sources

5.3e Organic Solvation Processes

5.3e Organic Solvation Processes

The next process type is using an organic solvent, such as the Organosolv (OS) process or the Cellulose solvent- and Organic Solvent-based LIgnocellulose Fractionation (COSLIF) process. For the OS pretreatment, the main mechanism involves the dissolution of lignin by organic solvent and then re-precipitation by adding an antisolvent, such as acidified water. This method was first introduced as a pulping method for papermaking. The organic solvents commonly used are acetone, ethanol, methanol, etc., in an aqueous solution of 20-60% water. Key parameters include temperature, residence time, chemical addition, and the water concentration. The effect is to: separate lignin from lignocellulosic biomass; solubilize hemicellulose; and increase pore size and surface area in the cell wall. Figure 5.24 shows a schematic of a process diagram for OS pretreatment.

 Organosolv (OS) process flow diagram
Figure 5.24: Organosolv (OS) process flow diagram*.
Credit: Pan et al., 2006. Biotechnol Bioeng. , 94: 851-61

Another organic solvent based process is cellulose-solvent and organic-solvent lignocellulose fractionation (COSLIF). For this process, an organic solvent is introduced to dissolve cellulose prior to Organosolv processing. Figure 5.25 shows a schematic of COSLIF processing.

 Cellulose-solvent and organic-solvent lignocellulose fractionation (COSLIF) diagram Before and after COSLIF images
Figure 5.25: Cellulose-solvent and organic-solvent lignocellulose fractionation (COSLIF) diagram and resulting effects.
Credit: Zhang et al., 2007. Biotechnol. Bioeng., 97: 214–223