Destruction of environmentally hazardous halogenated hydrocarbons in stable ionic liquids with superoxide ion radical

Saleem S. AlSaleem, Waleed M. Zahid, Inas M. Alnashef, Husnain Haider

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Ionic liquids (ILs) have been investigated as a media for destruction of halogenated hydrocarbons (HHCs) because of their affinity to solubilize pollutants, hydrophobicity, ability to generate and maintain free radicals, and long term stability with superoxide ion radical (O2[rad]−). Three HHCs (CCl₄ CHCl3, and CHBr3) were successfully destructed by O2[rad]− in 13 hydrophobic ILs, including two piperidinium (PIP-ILs), four pyrrolidinium (PYRR-ILs), and seven ammonium-cation based ILs (AM-ILs). The effects of contact time and potassium superoxide (KO2) dose on the destruction efficiency were evaluated using analysis of variance. 1-propyl -1- methylpiperidinium, 1-octyl-1-Methylpyrrolidinium, and octyltriethylammonium paired with bis (trifluoromethylsulfonyl) imide were found to be the best performers amongst PIP-ILs, PYRR-ILs, and AM-ILs. CHCl3, CCl₄ and CHBr3 consumed about 8, 11, and 14 KO2/HHC mole ratio to achieve 95% of optimum destruction efficiency. High viscosity was identified as the main drawback of [N8881][Tf2N] and [N4441][Tf2N]. Destruction was moderately fast and steady state efficiency was achieved within 30 min. The strong correlations between empirical polarity ETN of HHCs, work as co-solvents, and destruction efficiencies were obtained with R2 values higher than 0.99. The study presents a useful insight to use ILs as alternative solvents for treatment of hazardous wastes.

Original languageBritish English
Pages (from-to)134-142
Number of pages9
JournalSeparation and Purification Technology
Volume215
DOIs
StatePublished - 15 May 2019

Keywords

  • Ammonium-based ionic liquids
  • Halogenated Hydrocarbons
  • Piperidinium
  • Pyrrolidinium
  • Superoxide ion radical

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