Removal of Benzothiophene by Extraction with Deep Eutectic Solvents[Bmim]Br-Polyalcohol

Deep eutectic solvents(DESs)1-butyl-3-methylimidazolium bromide-polyalcohol([Bmim]Br-polyalcohol)were synthesized from[Bmim]Br and polyalcohol such as ethylene glycol(EG),propylene glycol(PG),glycerol(GL)at a molar ratio of 1:2.[Bmim]Br-2propylene glycol([Bmim]Br-2PG)was characterized with FT-IR spectroscopy and 1H NMR.The removal of benzothiophene(BT)from model oil was investigated by extraction with DES[Bmim]Br-2PG.The results showed that an extraction efficiency as high as 54.1%could be achieved with the solvent in one-stage extraction at 30℃in 30 min with a DES/oil mass ratio of 1:1.Deep desulfurization was realized after five-stage extraction,and sulfur content in model oil was reduced to less than 10μg/g.The used[Bmim]Br-2PG DES was regenerated and showed an extraction efficiency of 50.5%within four recycles.