Orthogonal array design for the optimization of stripping Sr(Ⅱ) from ionic liquids using supercritical CO2

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.

Stripping of uranium from an ionic liquid medium by TOPO-modified supercritical carbon dioxide

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%.

Adsorption of cesium using mesoporous silica gel evenly doped by Prussian blue nanoparticles

In this paper,a novel mesoporous silica gel evenly doped by Prussian blue nanoparticles(PBMSG) was successfully synthesized by using N,N-dimethylamide as template with a large Barrett-Emmett-Teller(BET) surface area of 505 m^(2)/g and an average pore size of 2.9 nm.The static adsorption experiments showed that the equilibration time of PBMSG for Cs^(+) was about 30 min.The adsorption isotherm of PBMSG for Cs^(+) accorded with Langmuir model and the theoretical maximum adsorption capacity was80.0± 2.9 mg/g.When the initial concentration of Cs^(+) was 1.00 mg/L,the adsorption partition coefficient Kd could reach 3.5 × 10^4 mL/g After adsorption,Cs+ could be eluted by dilute hydrochloric acid(pH2) with an efficiency of 89.8%,while no K^(+),Fe^(3+),Fe^(2+) was eluted.PBMSG exhibited good selectivity toward Cs^(+) and Rb^(+).In the presence of high concentration of K^(+),the selective adsorption of PBMSG could change the mass ratio of K^(+),Rb^(+) and Cs^(+) from 96.63:0.83:1.00-1.12:0.73:1.00.The separation of Cs^(+) and Rb^(+) from K^(+) with similar concentration(100 mg/g) was realized by column experiment.This indicated that PBMSG was suitable for rapid recovery of low concentration of rubidium and cesium from complex matrixes,such as wastewater and salt lake brine,etc.

Preparation and characterization of a novel single crystal ofTh(Ⅳ) with cucurbit[6]uril

One single crystal based on Th4＋ and cucurbit[6]uril （CB6） in nitric acid aqueous solutions was synthesized by slow evaporation method. The single crystal was characterized by elemental analysis, single crystal X-ray diffraction, XRD, FT-IR and TGA. The complexed cation of Th4＋ is a ten coordinated structure, in which the central thorium ion is coordinated by six monodentate water molecules and two bidentate nitrates. While CB6, as a second-sphere ligand, coordinates with the water molecules of [Th （NO3）2（H2O）6]2＋ through the formation of hydrogen bonding. Two other nitrate ions act as the counter anions. Besides, there are two free water molecules in the crystal system. The formation of the Th4＋-CB6 complex can contribute to the study of the coordination of CB6 and the extraction of Th4＋ in HN03 system