Using UCST ionic liquid as a draw solute in forward osmosis to treat high-salinity water

Yujiang Zhong, Xiaoshuang Feng, Wei Chen, Xinbo Wang, Kuo-Wei Huang, Yves Gnanou, Zhiping Lai

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The concept of using a thermo-responsive ionic liquid (IL) with an upper critical solution temperature (UCST) as a draw solute in forward osmosis (FO) was successfully demonstrated here experimentally. A 3.2 M solution of protonated betaine bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) was obtained by heating and maintaining the temperature above 56°C. This solution successfully drew water from high-salinity water up to 3.0 M through FO. When the IL solution cooled to room temperature, it spontaneously separated into a water-rich phase and an IL-rich phase: the water-rich phase was the produced water that contained a low IL concentration, and the IL-rich phase could be used directly as the draw solution in the next cycle of the FO process. The thermal stability, thermal-responsive solubility and UV-vis absorption spectra of the IL were also studied in detail.
Original languageEnglish (US)
Pages (from-to)1039-1045
Number of pages7
JournalEnvironmental Science & Technology
Issue number2
StatePublished - Dec 28 2015

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KAUST Repository Item: Exported on 2020-10-01


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