The extraction of thorium(IV) was investigated using two types of W/O microemulsion,one of which was formed by a surface-active saponified extractant sodium bis(2-ethylhexyl) phosphate(NaDEHP) and the other was formed by a mixture of an anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate(AOT) and an extractant bis(2-ethylhexyl)phosphoric acid(HDEHP) as the cosurfactant.The extraction capacities of the above two systems were higher than that of the HDEHP extraction system.High concentration of NaNO 3 showed no influence on the extraction in the NaDEHP based W/O microemulsion system,whilst reduced the extractability in the AOT-HDEHP W/O microemulsion system.The mechanism in acidic condition was demonstrated by the log-log plot method.The structure of the aggregations and the water content in the organic phase after extraction were measured by dynamic light scattering and Karl Fischer water titration,respectively.It was found that NaDEHP based W/O microemulsion broke up after extraction,while AOT-HDEHP W/O microemulsion was reserved.
The study of cyclodextrin nanotubes is a significant topic among the self-assembly behaviors of cyclodextrins.We report herein the interaction of 2,5-bis(5'-tert-butyl-2-benzoxazoyl)thiophene(BBOT) with α-,β-,γ-cyclodextrins(CDs).It has been discovered that the reaction patterns of BBOT with CDs are remarkably different.α-CD forms a simple inclusion complex with BBOT in a stoichiometry of 1:2(guest:host).β-CD forms a 1:1 inclusion complex with BBOT at its low concentration.At higher concentration of BBOT,the nanotube and secondary assembly of β-CD are formed.As for γ-CD,the nanotube and secondary assembly are formed within the whole concentration range of BBOT studied.The structure of γ-CD nanotubes is different from that of β-CD nanotubes to a certain extent.
ZHANG JingJing,SHEN XingHai,WU AiHua,ZHANG ChunFen,CHEN QingDe & GAO HongCheng Beijing National Laboratory for Molecular Sciences
The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluoromethyl)sulfonyl]imide (C2 mimNTf2 ). The concentrations of both the cation C2 mim + and the anion NTf2 in aqueous phase were detected. The con-centration of NTf2 in the aqueous phase decreased as Sr2+ or Cs+ exchanged into the IL phase. Addition of C2 mim + or NTf2 as well as the variation of the solubility of C2 mimNTf2 influenced the extraction efficiency of Sr2+ or Cs+ .
The extraction of strontium ions using DCH18C6 as the extractant and various ionic liquids (ILs) as solvents has been investigated. The distribution ratio of Sr2+ can reach as high as 103 under certain conditions, much larger than that in DCH18C6/n-octanol system. The extraction capacity depends greatly on the structure of ionic liquids. In IIs-based extraction systems, the extraction efficiency of strontium ions is reduced by increasing the concentration of nitric acid and can also be influenced directly by the presence of Na+ and K+ in the aqueous phase. It is confirmed that the extraction proceeds mainly via a cation-exchange mechanism.
