Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal

- A novel IL-based technology is developed for removing VOCs from the atmosphere.
- [Bmim][NTf2] is shown to be a promising absorbent for VOC pollutants.
- Absorptivity of [Bmim][NTf2] for toluene is >94% over a wide range of conditions.
- Toluene is easily removed from [Bmim][NTf2] permitting IL reuse in multiple cycles.

A novel method of removal of volatile organic compounds (VOCs) using the ionic liquid [Bmim][NTf2] as an absorbent is developed as a contribution to dealing with recent severe smog incidents in China. The effects of concentration, temperature and flow rates on the ability of [Bmim][NTf2] to absorb VOCs were studied using toluene as a model volatile organic pollutant. The potential of the use of [Bmim][NTf2] as an absorbent for VOCs is shown by the solubility of toluene in the ionic liquid; the absorptivity of the ionic liquid for toluene; and the fact that absorbed toluene can be removed easily from [Bmim][NTf2], permitting recycle of the ionic liquid in multiple reuse phases. The solubility of toluene in [Bmim][NTf2] is 61.5% at 20 °C and atmospheric pressure; the highest absorptivity of [Bmim][NTf2] for toluene is 98.3%, achieved at a toluene concentration of 300 ppm and a flow rate of 50 mL min−1 at 20 °C; and the absorptivity of the ionic liquid is >94% over a wide range of conditions. The ionic liquid can be recovered and recycled in the absorption process at least five times, reducing the reagent cost in the VOC removal process.