Separation of chemical groups from bio-oil water-extract via sequential organic solvent extraction

• Sequential extraction separated chemicals in bio-oil into different groups.
• Chloroform extracted 62 wt.% of furans, ketones, alcohols and phenolics.
• Ethyl acetate extracted 62 wt.% of acetic acid.
• Sequential extraction concentrated levoglucosan to 53 wt.% in final aqueous phase.

The chemical complexity of bio-oil aqueous phase limits its efficient utilization. To improve the efficiency of the bio-oil biorefinery, this study focused on the separation of chemical groups from the bio-oil water-extract via sequential organic solvent extractions. Due to their high recoverability and low solubility in water, four solvents (hexane, petroleum ether, chloroform, and ethyl acetate) with different polarities were evaluated, and the optimum process conditions for chemical extraction were determined. Chloroform had high extraction efficiency for furans, phenolics, and ketones. In addition to these classes of chemical, ethyl acetate had a high extraction efficiency for organic acids. The sequential extraction using chloroform followed by ethyl acetate resulted in 62.2 wt.% of original furans, ketones, alcohols, and phenolics being extracted into chloroform, while 62 wt.% acetic acid was extracted into ethyl acetate, leaving behind a high concentration of levoglucosan (∼53.0 wt.%) in the final aqueous phase. Chemicals separated via the sequential extraction could be used as feedstocks in a biorefinery using processes such as catalytic upgrading of furans and phenolics to hydrocarbons, fermentation of levoglucosan to produce alcohols and diols, and hydrogen production from organic acids via microbial electrolysis.

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