(335g) Extraction of Inhibitory Compounds Presented in Lignocellulose Hydrolysate with Selected Solvents

Pretreatment of lignocellulosic biomass, especially those using acids and water, leads to degradation of sugars and release of lignin based products (phenolic compounds). These compounds inhibit the fermentation and hence detoxification of hydrolysate is required. Phenolic compounds, even present in small quantity are highly toxic. This work explores the use of selected organic solvents for extraction of inhibitors commonly presented in lignocellulosic hydrolysates. Partition coefficient was obtained for all the solvents after mixing and incubating at 30oC for 24 h. Further, operating conditions (temperature, incubation time, and solvent to aqueous phase ratio) were optimized for enhanced extraction. Among the eight solvents tested, hexanol, octanol, and isooctyl alcohol exhibited much higher partition coefficients (>6) than the other five for phenolic compounds extraction. However, their partition coefficients were low for furfural, HMF, and acetic acid. Hence operating conditions (temperature and solvent to aqueous phase ratio) were optimized for improved separation of these compounds. Temperature was found having no significant effect on the partition coefficient. However, high solvent to aqueous phase ratio enhanced the separation. Further, the possibility of continuous extraction was tested with the best solvent (hexanol) by studying the effect of incubation time on extraction. It was observed that incubation time have insignificant effect on extraction. Thus these solvents might be utilized for continuous extraction of inhibitors from hydrolysates prior to fermentation.