Extraction of phenols from bio-oil aqueous fraction by hydrophobic ionic liquids
Jingjing Deng, Zejun Luo, Chu Wang, Xi-feng ZHU
Abstract
Acetic acid, phenol, guaiacol and 4-methylguaiacol in bio-oil aqueous fraction were extracted and separated experimentally with the choice of hydrophobic ionic liquid [Bmim][NTf 2 ] as extractant. The effects of extraction time and extractant dosage on the extraction efficiency were explored. With the help of density functional theory (DFT) calculations, the interaction mechanism between [Bmim][NTf 2 ] and phenol was also clarified. The results showed that under the optimal extraction condition ( m IL / m W = 0.4, extraction time = 5 min), the extraction efficiencies of acetic acid, phenol, guaiacol and 4-methylguaiacol in the aqueous fraction were 2.71%, 95.41%, 92.04%, and 97.98%, respectively. It was indicated that [Bmim][NTf 2 ] had better selectivity and superior extraction efficiency for phenols in bio-oil aqueous fraction. The results of DFT calculation demonstrated that the strong hydrogen bonding interaction as well as weak vdW interaction between [Bmim][NTf 2 ] and phenols played an important role in extraction and dephenolization of bio-oil aqueous fraction. The phenols in [Bmim][NTf 2 ] can be effectively removed by alkali washing treatment to achieve recovery of [Bmim][NTf 2 ] and next high efficiency extraction.