Temperature effect on U(VI) sorption onto Na-bentonite
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Ziqian Yang
Abstract
U(VI) sorption on a purified Na-bentonite was investigated from 298±2 to 353±2 K by using a batch experimental method as a function of pH, U(VI) concentration, carbonate concentration and solid-to-liquid ratio (m/V). The data at 298±2 K could be well described by a surface complexation model (SCM) with a complex located on layer sites (X2UO2) and three complexes located on edge sites (≡SOUO2+, ≡SO(UO2)3(OH)5, and ≡SO(UO2)3(OH)72−). The intrinsic equilibrium constants (Kint) of the surface reactions at 333 ± 2 and 353±2 K were obtained by fitting U(VI) sorption curves vs. pH on the Na-bentonite. The model enables U(VI) sorption in the presence of carbonate (pCO2=10−3.58 atm) to be described without considering any ternary surface complexes involving carbonate, except for underestimation around pH 7 (6<pH<7.5). The standard enthalpy changes (ΔrHmθ) of the surface reactions were evaluated from the Kint values obtained at three temperatures (298±2, 333±2 and 353±2 K) via the van´t Hoff equation. The proposed SCM and ΔrHmθ of the surface reactions enable U(VI) sorption on the Na-bentonite at other temperatures to be predicted.
© by Oldenbourg Wissenschaftsverlag, Lanzhou, Germany
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Artikel in diesem Heft
- New cross section measurements for the production of the Auger electron emitters 77Br and 80mBr
- Development of a SISAK extraction system for chemical studies of element 108, hassium
- Spectroscopic study on the mononuclear hydrolysis species of Pu(VI) under oxidation conditions
- Origin assessment of uranium ore concentrates based on their rare-earth elemental impurity pattern
- Performance of the mesh-type liquid cadmium cathode structure for the electrodeposition of uranium from the molten salt
- Temperature effect on U(VI) sorption onto Na-bentonite
- Rapid separation method for actinides in emergency soil samples
- Effect of solvent on the extraction of lanthanides with picrolonic acid
- Separation and purification of no-carrier-added arsenic from bulk amounts of germanium for use in radiopharmaceutical labelling
- Labelling and optimization of PHOTOFRIN® with 99mTc
- Appreciation to Referees
