13-28: Removal phenolic compounds from ionic-liquid pretreated hydrolysate for succinic acid fermentation

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Heng Shao1, Patricia Relue2, Sasidhar Varanasi3, Bin Li1 and Kelly Marbaugh4, (1)Bioengineering, The University of Toledo, Toledo, OH, (2)Department of Bioengineering, The University of Toledo, Toledo, OH, (3)Chemical and Environmental Engineering, The University of Toledo, Toledo, OH, (4)Bioengineering, University of Toledo, Toledo, OH
Following pretreatment of ligocellulosic biomass, hydrolysate rich in monomeric sugars is produced, but often a broad range of low concentration inhibitors are also present. Solubilized lignin or lignin derivatives, such as phenolic compounds produced with ionic liquid pretreatment are inhibitory to cell growth and productivity.

Actinobacillus succinigeneis 130z is quite flexible in its ability to efficiently produce succinic acid through fermentation of different carbon sources commonly found in hydrolysate. But this strain is very sensitive to some phenolic compounds present in biomass hydrolysate, resulting in dramatically reduced fermentation efficiency and succinic acid yield. This inhibition is more serious in concentrated hydrolysate where both sugars and inhibitors may be 4 to 10 times higher in concentration than in the original hydrolysate. So the detoxification process is required before the fermentation start.

Current methods for removing the phenolic compounds include adsorption on activated carbon or ion-exchange resins. In addition to being expensive, there methods are non-selective and less efficient. Therefore, we propose to use two-phase liquid extraction instead. The phenolic compounds are removed from the aqueous solution and transported to the low-toxic and immiscible organic solvent (e.g. hexane, 2-octanol) containing an extractant, tri-n-octyl phosphine oxide (TOPO). The extracted phenolic compounds can be stripped from the organic into a higher pH aqueous receiving phase to regenerate the organic phase. These three methods, activated carbon, ion-exchange resins and two-phase liquid extraction, will be compared for ionic liquid hydrolysates, with and without concentration, with respect to sugar loss and phenolic compounds removal efficiency to evaluate performance.

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