Upgrading of Bio-oil: Removal of the Fermentation Inhibitor (Furfural) from the Model Compounds of Bio-oil Using Pyrolytic Char

To effectively transform sugar-enriched bio-oil to fuel ethanol, it is important to develop a cost-effective approach to the removal of the fermentation inhibitors. In this study, pyrolytic char from biomass pyrolysis was utilized to remove the representative fermentation inhibitor (furfural) in order to develop a new method to upgrade the bio-oil, which can then be used to produce bioethanol. As the bio-oil compound is complex, the method was initially explored using model compounds. The properties of the pyrolytic char (bamboo charcoal) were first analyzed and the effects of various experimental parameters on the adsorptive removal of furfural were evaluated. Results showed that temperature has little effect on the adsorption of furfural. Because of the pi-pi interaction between the adsorbent and adsorbate, the bamboo charcoal tends to adsorb furfural despite the presence of sugar. The kinetic mechanism of furfural onto the pyrolytic char was proposed. The intraparticle diffusion model revealed that the pore diffusion (from macropore to micropore) is the main rate-controlling step in the adsorption process of furfural. Results confirmed that pyrolytic char is an effective and promising adsorbent for the removal of furfural from bio-oil with minimal loss of sugars.