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In order to examine the chemical form of uranyl species in 1-ethyl-3-methylimidazolium(EMI) based ionic liquids,UV-visible absorption spectra of solutions prepared by dissolving [EMI] 2 [UO2Cl4] into a mixture of EMICl and EMIBF 4(50:50 mol%) were measured.As a result,it was confirmed that uranyl species in the mixture of EMICl and EMIBF 4 existed as [UO2Cl4]2-.Cyclic voltammograms(CVs) of [UO2Cl4]2-in the mixture were measured at 25 ℃ using a Pt working electrode,a Pt wire counter electrode,and an Ag/Ag + reference electrode(0.01 M AgNO 3,0.1 M tetrabutylammonium perchlorate in acetonitrile) in a glove box under an Ar atmosphere.Peaks corresponding to one redox couple were observed around-1.05 V(Epc) and-0.92 V(Epa) vs.ferrocene/ferrocenium ion(Fc/Fc +).The potential differences between two peaks(Ep) increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s-1,while the(Epc+Epa)/2 value was constant,-0.989 V vs.Fc/Fc + regardless of the scan rate.Furthermore,the diffusion coefficient of [UO2Cl4]2-and the standard rate constant were estimated to be 3.7 × 10-8 cm 2 s-1 and(2.7-2.8) × 10-4 cm s-1 at 25 oC.By using the diffusion coefficient and the standard rate constant,the simulation of CVs was performed based on the reaction,[UO2Cl4]2-+ e = [UO2Cl4]3-.The simulated CVs were found to be consistent with the experimental ones.From these results,it is concluded that [UO2Cl4]2-in the mixture of EMICl and EMIBF 4 is reduced to [UO2Cl4]3-quasi-reversibly at-0.989 V vs.Fc/Fc +.
In order to examine the chemical form of uranyl species in 1-ethyl-3-methylimidazolium (EMI) based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI] 2 [UO2Cl4] into a mixture of EMICl and EMIBF 4 (50:50 mol%) were measured. As a result, it was confirmed that uranyl species in the mixture of EMICl and EMIBF 4 existed as [UO2Cl4] 2-.Cyclic voltammograms (CVs) of [UO2Cl4] 2-in the mixture were measured at 25 ° C using a Pt working electrode, a Pt wire counter electrode, and an Ag / Ag + reference electrode (0.01 M AgNO 3, 0.1 M tetrabutylammonium perchlorate in acetonitrile) in a glove box under an Ar atmosphere. Peaks corresponding to One redox couple were observed around -1.05 V (Epc) and-0.92 V (Epa) vs. ferrocene / ferrocenium ion (Fc / Fc +). The potential differences between two peaks (Ep) increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s-1 while while (Epc + Epa) / 2 value was constant, -0.989 V vs. Fc / Fc + regardless of the scan rate. Stillrther, the diffusion coefficient of [UO2Cl4] 2-and the standard rate constant were estimated to be 3.7 × 10 -8 cm 2 s-1 and (2.7-2.8) × 10 -4 cm s-1 at 25 o C. By using the diffusion coefficient and the standard rate constant, the simulation of CVs was performed based on the reaction, [UO2Cl4] 2- + e = [UO2Cl4] 3-. The simulated CVs were found to be consistent with the experimental ones. is meant that [UO2Cl4] 2-in the mixture of EMIC1 and EMIBF4 is reduced to [UO2Cl4] 3-quasi-reversibly at-0.989 V vs. Fc / Fc +.