疏水性离子液体对生物油水相馏分中酚类物质的萃取研究

Extraction of phenols from bio-oil aqueous fraction by hydrophobic ionic liquids

选用疏水性离子液体[Bmim][NTf2]作为萃取剂,对生物油水相馏分中的乙酸、苯酚、愈创木酚、4-甲基愈创木酚进行萃取分离研究,探究萃取时间、萃取剂添加量对萃取率的影响,并借助密度泛函理论(DFT)计算,阐明[Bmim][NTf2]与酚类化合物间的相互作用机理。研究结果表明,在最佳萃取条件(mIL/mW=0.4、萃取时间=5 min)下,[Bmim][NTf2]对水相馏分中乙酸、苯酚、愈创木酚、4-甲基愈创木酚的萃取率分别为2.71%、95.41%、92.04%、97.98%,表明[Bmim][NTf2]对水相馏分中的酚类化合物有较好的选择性与较高的萃取率;而DFT计算结果显示,[Bmim][NTf2]与酚类物质间较强的氢键吸引作用以及较弱的范德华作用力在萃取脱酚中起着重要作用。通过碱洗处理即可将[Bmim][NTf2]中的酚类化合物有效除去,实现[Bmim][NTf2]的回收与再次高效萃取。

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][NTf2]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][NTf2]and phenol was also clarified.The results showed that under the optimal extraction condition(mIL/mW=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][NTf2]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][NTf2]and phenols played an important role in extraction and dephenolization of bio-oil aqueous fraction.The phenols in[Bmim][NTf2]can be effectively removed by alkali washing treatment to achieve recovery of[Bmim][NTf2]and next high efficiency extraction.