Abstract
The long-term stability of superoxide ion (O2•−) with four ionic liquids (ILs), namely 1-(2-methoxyethyl)-1-methylpiperidinium tris(pentafluoroethyl)trifluorophosphate [MOEMPip][TPTP], 1-(3-methoxypropyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide [MOPMPip][TFSI], N-ethyl-N,N-dimethyl-2-methoxyethylammonium bis(trifluoromethylsulfonyl)imide [N112,1O2][TFSI], and ethyl-dimethyl-propylammonium bis(trifluoromethylsulfonyl)imide [EDMPAmm][TFSI], was studied for up to 24 h using two-second intervals. This was achieved by chemical generation of O2•− by dissolution of potassium superoxide salt in dimethyl sulfoxide and the subsequent addition of the IL. The decrease in the concentration of O2•− after the introduction of the IL was monitored using a UV-vis spectrophotometer. The ammonium-based ILs were found to be more stable than piperidinium-based ILs. To the best of our knowledge, this was the first time that O2•− stability with ILs has been monitored continuously for up to 24 h. This should provide a better insight into the stability and kinetics of O2•− for industrial applications and its role in energy-storage devices. The most appropriate IL as a medium was [EDMPAmm][TFSI], and O2•− generated in this IL was used to destroy nearly 90% of thiophene.
Keywords:
Reactive oxygen species; Kinetics; Deep eutectic solvents; Green solvents; Desulfurization; Potassium superoxide; Hazardous material
