Use of Ionic Liquid-Based Ultrasound Assisted Liquid-Liquid Extraction of Phenols from Aqueous Fractions of Seed Bio-Oil

The liquid product of the pyrolysis of biomass is a mixture of an organic phase and other aqueous, being the last one rich in phenol monomers which can be used in industrial chemistry as input for plastic and resin production. This work aimed to develop a method for extracting phenols present in the aqueous fraction obtained from the pyrolysis of guava seeds, using ultrasonic assisted liquid-liquid extraction (UALLE) with ethyl acetate and ionic liquids (ILs) as co-solvents (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide (BMIM.NTF2) and 1-butyl-3-methylimidazolinium hexafluorophosphate (BMIM.PF6)). The percentage IL, ultrasonic bath potency, temperature, and pH were studied. Quantification of twelve phenol monomers was performed using gas chromatography-mass spectrometry (GC-MS) and the total phenol concentration (TPC) was performed using UV-Vis spectrophotometer. The ionic liquid BMIM.NTF2 was more efficient for phenol extraction than BMIM.PF6. The phenolic extractions were influenced by the pH of the aqueous fraction (higher extraction yields at pH ≤ 7), and thus, presented recoveries above 80% for both ionic liquids.

生物质热解所得液态产物为有机相与水相的混合体系，其中水相富含苯酚单体，可作为工业化学领域生产塑料与树脂的原料。本研究旨在开发一种提取番石榴籽热解所得水相馏分中酚类物质的方法，采用以乙酸乙酯和离子液体（ionic liquids, ILs）为助溶剂的超声辅助液液萃取（ultrasonic assisted liquid-liquid extraction, UALLE）技术，所用助溶剂包括1-丁基-3-甲基咪唑双(三氟甲磺酰基)亚胺（1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide, BMIM.NTF2）与1-丁基-3-甲基咪唑六氟磷酸盐（1-butyl-3-methylimidazolinium hexafluorophosphate, BMIM.PF6）。本研究考察了离子液体体积分数、超声功率、反应温度及溶液pH值等因素的影响。采用气相色谱-质谱联用仪（gas chromatography-mass spectrometry, GC-MS）对12种苯酚单体进行定量分析，并采用紫外-可见分光光度计（UV-Vis spectrophotometer）测定总酚浓度（total phenol concentration, TPC）。实验结果表明，相较于BMIM.PF6，离子液体BMIM.NTF2的酚类萃取效果更优。酚类萃取效果受水相pH值影响显著，当pH≤7时萃取产率更高；两种离子液体的酚类回收率均可达80%以上。