Abstract:

Separation of phenols from oil via forming deep eutectic solvents (DES) is an efficient method. During the extraction, however, oil entrainment occurs, which influences the separation efficiency. In this work, the effects of added choline chloride (ChCl) amount, extraction temperature and concentration of straight-chain paraffin in model oil on the separation of phenols and oil entertainment in DES phase via forming DES were investigated. Toluene solution with 200 g·L^-1 phenol was used as model oil and ChCl was used as extraction agent. The results showed that the separation efficiency of phenol from model oil increased with the increase of addition of ChCl and the increase of addition of ChCl could also reduce the entrainment of toluene in DES phase. The effect of temperature on the separation of phenol was not significant. The entrainment of toluene increased with the increase of temperature at low ratios of added ChCl to phenol; while it did not change significantly at high ratios of added ChCl to phenol. The entrainment of toluene was reduced with the increase of the concentration of aliphatic hydrocarbon. With ChCl as extraction agent, typically, the separation efficiency of phenol was 95% and the entrainment of toluene was 15% at 25℃ and mole ratio of ChCl to phenol of more than 0.6. Toluene could be removed completely within 60 min with nitrogen purging at 70℃.

Key words: deep eutectic solvent, phenol-oil mixture, separation, entrainment

摘要：

采用季铵盐与酚形成低共熔溶剂(DES)从含酚的混合物中萃取分离酚是一种有效的油酚分离方法, 然而分离过程中, 中性油的夹带会影响分离效率。以含苯酚200 g·L^-1的甲苯溶液作为模拟油酚混合物, 氯化胆碱(ChCl)作为分离剂, 研究了氯化胆碱的加入量、萃取温度(25～55℃)及模拟油中直链烷烃的浓度等因素对酚的萃取分离及中性油夹带的影响。结果表明, 随着ChCl加入量增大, 酚萃取率升高, 中性油的夹带量减少;ChCl过量时, 酚的萃取量恒定且达到极大值, 中性油夹带量恒定且夹带量最小;萃取温度对酚的萃取率影响不大, 对中性油的夹带量在ChCl加入量不足时随温度升高而增多, 当ChCl加入量足量时与温度变化关系不大;模拟油中直链烷烃的浓度不影响萃取效率, 浓度越高, 甲苯夹带越少。以ChCl萃取含苯酚200 g·L^-1的甲苯溶液, 在萃取温度25℃、ChCl加入量大于0.6(与酚的摩尔比)的条件下, 苯酚萃取率达95%, 甲苯夹带率为15%, 70℃条件下氮气吹扫60 min内可将DES中甲苯完全去除。

关键词: 低共熔, 油酚混合物, 分离, 夹带