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

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 degrees 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 degrees 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. (C) 2017 Elsevier B.V. All rights reserved.