Generation of Superoxide Ion in Pyridinium, Morpholinium, Ammonium, and Sulfonium-Based Ionic Liquids and the Application in the Destruction of Toxic Chlorinated Phenols

Abstract

Generation of superoxide ion (O2•–) was carried out in four ionic liquids (ILs) having the same anion, bis(trifluoromethylsulfonyl)imide [N(Tf)2]−, and different cations, N-hexylpyridinium [HPy]+, N-methoxyethyl-N-methylmorpholinium [MO1,1O2]+, N-ethyl-N,N-dimethyl-2-methoxyethylammonium [N112,1O2]+, and triethylsulfonium [S222]+. Cyclic voltammetry (CV) and chronoamperometry (CA) electrochemical techniques were used in this investigation. It was found that O2•– is not stable in the [HPy]+-based IL. On the other hand, CV showed that the electrochemically generated O2•– is stable in [MO1,1O2]+-, [N112,1O2]+-, and [S222]+-based ILs for the time duration of the experiment. The long-term stability of the generated O2•– was then investigated by dissolving potassium superoxide (KO2) in dimethyl sulfoxide (DMSO) in the presence of the corresponding IL. It was found that ILs containing [MO1,1O2]+ and [N112,1O2]+ offer a promising long-term stability of O2•– for various reactions to be used for several application...