UO2＋, which is extracted from the aqueous phase into the 1-ethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide（C2mim NTf2） ionic liquid ph^ase with octyl（phenyl）-N,N-diisobutylcarbamoylmethylphosphine oxide（CMPO）, can be stripped by supercritical CO2. Trioctylphosphine oxide（TOPO）, the modifier added to the supercritical CO2 phase, enhances the stripping efficiency by up to 99%.
Two single crystals [Ln（TBPO）4（NO3）2]NTf2 （Ln = Eu, Gd） were prepared and characterized by element analysis, single crystal X-ray diffraction, PXRD, FT-IR, TGA and fluorescence spectroscopy. The two compounds have similar coordinate structures, in which the central metal ion is coordinated by four TBPO（Tri-n-butylphosphine oxide） molecules and two bidentate nitrates, while NTf2^-（bis（trifluor-（bis（trifluoromethylsulfonyl）imide anion） acts as the counter anion. The packing modes of the two crystals are same. The two single crystals are the focus on 8-coordinate tetra-TRPO complexes（TRPO is Trialkyphosphine oxides）.
Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO2 nanospheres（φ：30-50 nm,wall thickness：8-15 nm,and cavity diameter：10-20 nm）.The effect of HCOONH4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed.
The strontium ions extracted from the aqueous phase into 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(C_2mimNTf2) with dicyclohexyl-18-crown-6(DCH18C6) was stripped effectively by supercritical CO_2(sc-CO_2).Hexafluoroacetylacetone(HFAA)-acetonitrile was found to be an excellent modifier of sc-CO_2 to enhance the stripping efficiency.In the orthogonal array design(OAD),OA_(25)(5~5)matrix was employed to optimize the stripping of Sr(Ⅱ) from the DCH 18C6-C_2mimNTf_2 system.Effects of five experimental factors:temperature,pressure,concentration of HFAA,static and dynamic extraction times as well as each factor at five-levels on the stripping of Sr(Ⅱ) were optimized.The effects of these parameters were treated by the analysis of variance(ANOVA).The results showed that Sr(II) could be nearly 100%extracted from the IL phase at 308 K,30 MPa,40 min of dynamic extraction and 60 mmol·L^(-1) HFAA in acetonitrile,respectively.Finally,the stripping mechanism was studied by ESI-MS.
