Confirmation of radicals auto-generated in [Bmim][PF6]/[C16mim][PF6]/water reverse micelles and the radical quantification based on the 1,1-diphenyl-2-picrylhydrazine (DPPHH) spectroscopic probe.

Abstract

Ionic liquids (ILs) which belong to the molten salt of a high ionic environment exhibit a number of unique properties, including the formation of various heterogeneities in their microemulsion. We found that auto-generated radicals within a [Bmim][PF₆]/[C₁₆mim][PF₆]/PBS reverse micelles (IL-RMs) and then the radicals were quantified in this study. For the radical confirmation, EPR spectroscopy with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) free radical scavenger was carried out. A spectroscopic chemical probe of 1,1-diphenyl-2-picrylhydrazine (DPPHH) was employed to quantify the radicals in the IL-RM systems. The mechanism of the radical generation was also proposed. The DPPHH probe method is simple, rapid, and sensitive to quantify free radicals in the IL-RM systems. Finally, IL-RMs were successfully applied to degrade Rhodamine B (Rho-B) dye with low degradation cost, simple operation, short time consumption, and remarkable degradation effect. The results show a near 100% degradation rate for 10 μmol·L^-1 Rho-B in the IL-RMs system with pH 7.4 PBS containing 1 mmol·L^-1 chloroacetic acid as an aqueous phase.