A Novel Functionalized Ionic Liquid for Highly Selective Extraction of TcO4.

Due to the highly acidic and high-salinity nature of the high-level radioactive waste liquid (HLLW), selective extraction of TcO4- from HLLW remains to be a challenging task. Traditional anion exchangers show low selectivity and unsatisfactory extraction performance due to the lack of functional groups that can interact strongly with TcO4-. In this work, a tailor-made binding site was constructed by decorating two acetamide functional groups on imidazolium cation to fabricate a new Tc separation material, which exhibits high selectivity. Unlike most reported Tc separation materials, which can only perform well under low acidic, neutral, or alkaline conditions, this material still has good extraction performance in highly acidic solutions. In the simulated high-level waste liquid of 3 M nitric acid, the extraction efficiency of 0.5 mol/L organic phase for Tc can reach 96.5% through the first-stage extraction. Our theoretical simulations suggest that ReO4-/TcO4- anions were adsorbed on the top of the imidazolium ring during the extraction process, with p-π and p-p interactions acting as the driving forces.

Highly Efficient Uptake of TcO4 - by Imidazolium-Functionalized Wood Sawdust.

99Tc is a radioactive fission product, mainly in the form of TcO4 -, with good solubility and mobility in the environment. The development of effective and inexpensive materials to remove TcO4 - from nuclear industry wastewater or contaminated water is significant. Wood sawdust is a byproduct of the wood processing industry and is an abundant, low-cost, and sustainable material. The mesostructure of wood consists of numerous hollow cells that are joined endwise to form an interconnected channel matrix capable of rapid transfer of ions. Imidazolium-functionalized wood sawdust (IM-WS) was synthesized using natural wood sawdust by a two-step reaction. It has excellent properties of TcO4 -/ReO4 - adsorption including rapid adsorption dynamics (30 s to equilibrium), good adsorption stability (pH 3-9), high selectivity (adsorption of 45.4 Re % in 1000 times excess of NO3 - ions, 76.6 Re % in 6000 times excess of SO4 2- ions, and 92.2 Tc % in a simulated mixed solution; after adsorption, the concentration of TcO4 - decreased to 0.056 ppb from the initial concentration of 12.09 ppb in 1000 times excess of SO4 2-), and in particular low production costs. These characteristics give it great prospects for low-level radioactive wastewater treatment and environmental remediation.

Preparation of a mesocellular siliceous foam supported lanthanide-sensitive polymer for the selective adsorption of lanthanides.

A ship in bottle nanocomposite was fabricated as a novel adsorbent for lanthanides by immobilizing a lanthanide-sensitive polymer into mesocellular siliceous foam (MCF). The MCF was used as a novel carrier for immobilization of the polymer, and the polymer was synthesized via in situ ring-opening polymerization of 2-methyl-2-oxazoline (MOL) and divinylbenzene (DVB) in the presence of MCFs. The substantially physically modified MCF-based composite exhibited superior adsorptivity and selectivity to lanthanides due to its exceptional properties, which was employed for lanthanide adsorption from aqueous solution by a facile solid-liquid separation procedure. The adsorption of lanthanides by the composite was systematically studied including adsorption parameter investigation and adsorption mechanism evaluation. The adsorption isotherms and kinetics were also investigated and proved to follow the Langmuir model and the pseudo-second-order model. The adsorption thermodynamics study indicated that the adsorption process was thermodynamically favorable, endothermic and spontaneous. The prepared inorganic-organic hybrid composite has superior selectivity and specificity to lanthanides, which can be used for lanthanide enrichment and separation of lanthanides from actinides.

Solvent extraction of lanthanides and yttrium from aqueous solution with methylimidazole in an ionic liquid.

1-Methylimidazole (1-MIM) and 2-methylimidazole (2-MIM) are miscible in water and imidazolium based ionic liquids (ILs), and can coordinate with soft metal ions. This paper reports a novel solvent extraction process for trivalent lanthanides and yttrium from aqueous solutions into ILs, which was promoted by a hydrophilic 1-MIM or 2-MIM. Slope analysis confirmed that MIM in ILs formed a 1 : 1 complex with La(3+) and Y(3+) and a 1 : 4 complex with Eu(3+) and Lu(3+), depending on the atomic number of the metal and the metal-ligand interactions that have been characterized by FTIR spectroscopy and ESI-MS. The effect of nitrate concentration on the extraction of lanthanides with 1-MIM in ILs was analysed. It indicated that nitrate anions were involved in the extraction process. Under the same conditions, the extraction of lanthanides with MIM into n-pentanol was carried out. The extractability was by far lower than that obtained in ILs. Both cationic exchange and neutral solvation mechanisms occurred in ILs and only the neutral solvation mechanism occurred in n-pentanol, which were demonstrated by the extraction tests and the structure of extracted species determined by ESI-MS. The competitive extraction in ILs showed good selectivity for lanthanides compared to alkali metals and alkaline earth cations. After extraction, lanthanides could be stripped very easily from the ionic liquid phase with dilute nitric acid. From the temperature dependence data, the thermodynamic parameter values (ΔH, ΔS and ΔG) were calculated. The results indicated that the extraction reactions were spontaneous and went through an endothermic process.

Determinations of the inclusion complex between gossypol and beta-cyclodextrin.

Features of the inclusion complex between gossypol (Gos) and beta-cyclodextrin (CD), such as its aqueous solubility, association constant, characteristics in the solid state and crystalline morphology, as well as the stoichiometry of this complex have been determined. The phase-solubility diagram drawn using UV detections belongs to an AN-type. Fluorescence detection and calculation with the modified Benesi-Hidebrond equation provide an 1:2 stoichiometry for the complex. Its apparent stability constant has been determined to be 3,203 M(-1) by fluorescence technique and confirmed by the calculation from UV spectroscopy. X-ray powder diffractions (XRD) and Scanning Electron Microscopy (SEM) observations showed a clear difference in the crystal morphology of the complex from those of both Gos and beta-CD.

Study on structure and characterization of inclusion complex of gossypol/beta cyclodextrin.

The inclusion complex of beta-cyclodextrin with gossypol was synthesized by using a convenient method of microwave irradiation. The structure of the complex was determined by 1H NMR, IR spectroscopy, and as well as the elemental analysis; the thermal stability was studied by means of differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The association constant between gossypol and beta-cyclodextrin measured via UV spectroscopy was 4462M(-1) at room temperature, following stoichiometry 1:2.