Removal and recovery of triphenylmethane dyes from wastewater with temperature-sensitive magnetic ionic liquid aqueous two-phase system

Abstract

In this report, temperature-sensitive magnetic ionic liquids (MILs) were discovered for the first time. Two polypropylene glycol 400 (PPG400) based temperature-sensitive MILs were synthesized, characterized and successfully applied to construct the first reported temperature-sensitive magnetic ionic liquid aqueous two-phase system (MILATPs). To the best of our knowledge, this proposed temperature-sensitive MILATPs combined the advantages of rapid extraction, organic solvent free for the whole process, magnetic separation and thermo-recovery of MIL in a separation process for the first time. Temperature-sensitive MILATPs were successfully applied for the removal and recovery of three triphenylmethane dyes from wastewater. Phase behaviors and several influencing factors on dye extraction efficiency were detailedly investigated and optimized with good performances. Both high purities of MIL and dye could be ideally recovered simply by heating and the recoveries of dyes were higher than 93%. Additionally, the two MILs could be recycled for at least 6 times with steadily high extraction efficiencies. Furthermore, this novel temperature-sensitive MILATPs had been successfully applied for real industrial dyed wastewater treatment with satisfactory recoveries of both MIL and dye. This novelly proposed temperature-sensitive MILATPs is simple and green method which is showing great potential in a separation-recovery process and the industrial treatment of dyed wastewater.