Authors:Qi Tao, Hongping He, Ray Frost, Peng Yuan, and Jianxi Zhu
Anionic surfactant and silane modified layered double hydroxides (LDHs) were synthesized through an in situ coprecipitation
method. The structure and morphology were characterized by XRD and TEM techniques, and their thermal decomposition processes
were investigated using infrared emission spectroscopy (IES) combined with thermogravimetry (TG). The surfactant modified
LDHs (H-DS) shows three diffractions located at 1–7° (2θ), while there is only one broad reflection for silane grafted LDHs
(H–Si) in this region. The morphologies of the H-DS and H–Si show fibrous exfoliated layers and curved sheets, respectively.
The IES spectra and TG curves indicate that alkyl chain combustion and dehydroxylation are overlapped with each other during
heating from 373 to 723 K in H-DS and to 873 K in H–Si. Sulfate anion transformation process occurs at 473 K in H-DS and 523 K
in H–Si. The derivant of sulfate can exist even above 1073 K. After further decomposition, the metal oxides and the new type
of Si–O compounds are formed beginning at around 923 K in silane modified sample.
Authors:Liu Wen-Tao, Zeng Shan, Yang Yan-Zhao, Han Jian, Zhu Tao, and Luo Chang-Hong
The i-butyldodecylsulfoxide (BDSO) was synthesized. The extraction of uranium(VI) has been carried out with BDSO in toluene from various HNO3 concentrations. It was found that the distribution ratio increases with increasing nitric acid concentration up to 3.0 mol/l and then decreases. The distribution ratios also increase with increasing extractant concentration. The extracted species appears to be UO2(NO3)2·2BDSO and the equilibrium constant value is 15.2. The influence of temperature, sodium nitrate and oxalate concentrations on the extraction was also investigated, and the thermodynamic functions of the extraction reaction were obtained.
Authors:Zeng Shan, Yang Yan-zhao, Zhu Tao, Han Jian, and Luo Chang-Hong
The parameters affecting the formation of the microemulsion were investigated and the microemulsion region was determined. The extraction of uranium(VI) from HNO3 solution into a water in oil microemulsion was studied. The effects of the concentration of extractant (TRPO), the volume ratio of oil to water and the acidity of outer water phase on the extraction equilibrium of uranium(VI) are discussed and the appropriate conditions are obtained. The result showed the microemulsion has great efficiency for uranium(VI) extraction.
Authors:Li Lin, Yang Yan-Zhao, Zeng Shan, Zhu Tao, and Sun Si-Xiu
The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP)
and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid,
sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change
for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol
and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar
ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO2(NO3)2 . BDSO . TBP.