INVESTIGATING THE LONG-TERM STABILITY AND KINETICS OF SUPEROXIDE ION IN DIMETHYL SULFOXIDE CONTAINING IONIC LIQUIDS AND THE APPLICATION OF THIOPHENE DESTRUCTION

摘要

The long-term stability of superoxide ion (O-2(center dot-)) 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 ethyldimethyl-propylammonium bis(trifluoromethylsulfonyl)imide [EDMPAmm][TFSI], was studied for up to 24 h using two-second intervals. This was achieved by chemical generation of O-2(center dot-) by dissolution of potassium superoxide salt in dimethyl sulfoxide and the subsequent addition of the IL. The decrease in the concentration of O-2(center dot-) after the introduction of the IL was monitored using a UV-vis spectrophotometer. The ammoniumbased ILs were found to be more stable than piperidinium-based ILs. To the best of our knowledge, this was the first time that O-2(center dot-) stability with ILs has been monitored continuously for up to 24 h. This should provide a better insight into the stability and kinetics of O-2(center dot-) for industrial applications and its role in energy-storage devices. The most appropriate IL as a medium was [EDMPAmm][TFSI], and O-2(center dot-) generated in this IL was used to destroy nearly 90% of thiophene.