(548c) Effects of Overliming and Activated Carbon on Carbonyl Inhibitors Removal and Butanol Fermentation in Biomass Hydrolysates

Lignocellulosic biomass as the most abundant sustainable resource can be converted into biofuels by enzymatic hydrolysis and subsequent microbial fermentation. However, considerable amount of inhibitory compounds were generated from the dilute acid pretreatment process. The carbonyl aldehydes and ketones have been suggested to the most potent inhibitors in the biomass hydrolysate, which significantly limit the efficient utilization hemicellulose hydrolysates. This study was aimed at the identification of these carbonyl inhibitors and their removal by overliming and activated carbon. Forty-six carbonyl compounds (including furans, aliphatic derivatives, aromatic monomers and aromatic dimers) were identified as potential inhibitors by gas chromatography-mass spectrometry (GC-MS). It was observed that overliming and activated carbon treatment could remove 73.9% and 82.2% of carbonyl inhibitors, respectively, but the treated hydrolysates were still not fermentable. The sequential overliming and activated carbon removed 92.6% of carbonyl inhibitors and resulted in remarkable fermentability and high butanol yield (0.22 g g^–1 sugar). The organic acid in the prehydrolysates were also analyzed by a liquid chromatography connected to a quadrupole time-of-flight (LC-Q-TOF) mass spectrometer. Activated carbon removed 92.9% phenolic acids, while overliming removed 40.2% of them. This study revealed the distinctive effects of overliming and activated carbon treatments on the prehydrolysates detoxification. Overliming removed more dialdehydes and diketones than activated carbon treatment, while activated carbon removed more phenolic acids than overliming.