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Abstract  

Radioactive impurities of153,159Gd were determined as160Tb and154Eu by pressurized displacement chromatography. They were separated by pressurized elution chromatography with α-hydroxyisobutyric acid-ascorbic acid system. As the result, radiochemically pure153,159Gd was obtained.

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Abstract  

Sorption of thorium (IV) on goethite was investigated as a function of contact time, pH, ionic strength, anions, solid-to-liquid ratio (m/V) and Th(IV) concentration using batch technique. The results showed that the sorption of Th(IV) was strong pH-dependence, and increased from ~10 to ~100% over the pH range of 2.0–4.0, and then kept a constant level in the higher pH range. The sorption of Th(IV) increased with increasing m/V and independent of ionic strength. It was clear that phosphate and FA significantly enhanced Th(IV) sorption on goethite. The sorption and desorption isotherms were investigated at pH 2.90 ± 0.05 and analyzed with Freundlich and Langmuir models, respectively. Compared to Langmuir model, Freundlich model could fit the experimental data better, according to the high relative coefficients.

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Abstract  

We have performed a large number of batch sorption experiments of uranyl onto SiO2 and examined the effects of nitrate or ionic strength, phosphate, fulvic acid(FA), phthalic acid (PH), salicylic acid (SA), and catechol (CA) on the uranyl sorption onto SiO2. Three sorption edges and three sorption isotherms at ionic strengths 0.05, 0.1, and 0.5 mol/L KNO3 were used to investigate the effect of ionic strength or nitrate on the sorption and the Langmuir, Freundlich, and Dubinin-Radushkevich models are used to simulate the sorption isotherms, respectively. Five sorption edges in the presence of phosphate, FA, PH, SA, and CA were compared with that in the absence of complexing ligand. The results suggest that the effect of complexation of uranyl with nitrate on the uranyl sorption can be negligible and the sorption can be described Freundlich and D-R model very well. The positive effect of phosphate on the uranyl sorption was found, though the extent of effect was decreased with increasing pH. The positive effect and the negative effect of FA on the uranyl sorption were found at low pH and high pH ranges, respectively. The sorption edge of uranyl sorption remained unaffected in the presence of PH in the pH 2–10. In the presence of SA, the no effect and the negative effect on the uranyl sorption were, respectively, found at low pH and high pH ranges. The negative effect of CA on the uranyl sorption was found in the pH 2–10.

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Abstract  

Sorption of Th(IV) on Zr2O(PO4)2 as a function of contact time, reaction temperature, pH, ionic strength and solid-to-liquid ratio (m/V) is studied under ambient condition by using batch technique. Effects of fulvic acid (FA), phosphate, sulfate and citrate on Th(IV) sorption are investigated in detail. A pseudo-second-order rate equation is used to simulate the kinetic sorption. The removal of Th(IV) increases with increasing pH and hardly depends on ionic strength. Sorption of Th(IV) increases with increasing m/V and reaction temperature. The presence of FA and phosphate enhances the sorption of Th(IV) on Zr2O(PO4)2 while sulfate and citrate decrease the sorption. The Langmuir and Freundlich models are used to simulate the sorption isotherm of Th(IV) on Zr2O(PO4)2 at different temperatures. The thermodynamic data (i.e., ∆H 0, ∆S 0, ∆G 0) are calculated from temperature dependent sorption isotherms. The results suggest that the sorption process of Th(IV) on Zr2O(PO4)2 is spontaneous and endothermic.

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Abstract  

Metal ions sorption can be significantly affected by the presence of other sorbates, especially of complexing ligands. In this study, the effect of Se(IV) on Eu(III) sorption onto TiO2 at different pH and Eu(III) concentration was investigated. Se(IV) was found to enhance Eu(III) sorption as a function of Se(IV) concentration. Constant capacitance model was successfully used to interpret the sorption experimental data. The solubility product of Eu2(SeO3)3 at ambient temperature was investigated to highlight the sorption mechanism of ternary sorption system. The pK sp value of Eu2(SeO3)3 was found to be 31.51 ± 0.95.

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Abstract  

For the selective extraction of Am(III) and Eu(III), quadridentate divalent phenolic Schiff bases-bis-salicylaldehyde ethylenediamine (H2salen) was investigated as a kind of extractant. The influences of alkaline cation, inorganic anion, ionic strength, pH and the concentration of H2salen on the distribution ratio of Am(III) and Eu(III) were investigated in detail. As a result, Am(III) and Eu(III) made anionic 1:1 complexes with the ligand (H2salen) and could be extracted into nitrobenzene as ion-pairs with a suitable monovalent counter anion in the aqueous solution, the extracted species were possibly of the type Am(H2salen) Eu(salen)Cl and Eu(H2salen)Cl3, respectively. The extractability of Eu(III) was significantly stronger than that of Am(III) and the maximum separation factor, SF(Am/Eu), was 96 at pH 4.0. The results indicated that H2salen had good selectivity for Am(III) and Eu(III).

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Abstract  

Two open-chain crown ethers 2,2'-(ethylenedioxy)bis[(8-quinolyloxymethyl)benzene], (L1), and 2,2'-(ethylenedioxy)bis[(8-quinaldyloxymethyl)benzene], (L2) have been prepared and characterized by using elemental analysis, IR spectra, 1H NMR spectra and positive-ion FAB mass spectra. The extraction of UO2 2+ and Th4+ by both open-chain crown ethers, L1 and L2 in chloroform as a diluent was studied at 25 °C. Extraction distribution ratios (D) of UO2 2+ and Th4+ were investigated as a function of pH, lithium picrate concentration, and extractant concentration. Based on the expertimental results, it was found that 1 : 1 complexes were formed involving either UO2 2+ or Th4+ with L1, and Th4+ with L2. The extractability of L1 for Th4+ is significantly higher than that for UO2 2+, the extractabilities of L1 and L2 for Th4+ being almost identical. L1 and L2 used here are not feasible for industry because of their relatively low extractabilities for Th4+ at pH<2.0 and for UO2 2+ at the extraction conditions used in this work.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Xiaobei Zheng
,
Feng Dong
,
Jing Yang
,
Xiaojiang Duan
,
Tingting Niu
,
Wangsuo Wu
, and
Jianjun Wang

Abstract  

This work reports the synthesis and preliminary biodistribution results of [131I]SIB-PEG4-CHC in tumor-bearing mice. The tributylstannyl precursor ATE-PEG4-CHC was synthesized by conjugation of ATE to amino pegylated colchicine NH2-PEG4-CHC. [131I]SIB-PEG4-CHC was radiosynthesized by electrophilic destannylation of the precursor with a yield of ~44%. The radiochemical purity (RCP) appeared to be >95% by a Sep-Pak cartridge purification. [131I]SIB-PEG4-CHC was lipophilic and was stable at room temperature. Biodistribution studies in tumor-bearing mice showed that [131I]SIB-PEG4-CHC cleared from background rapidly, and didn’t deiodinate in vivo. However, the poor tumor localization excluded it from further investigations as a tumor-targeted radiopharmaceuticals.

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Abstract  

Effects of pH, Eu(III) concentration, ionic strength, temperature and humic acid (HA) on Eu(III) sorption to iron oxides were investigated in detail. The sorption of Eu(III) to iron oxides was significantly dependent on pH and weakly dependent on ionic strength, and higher temperature was gainful to Eu(III) sorption. In the presence of HA, Eu(III) sorption was enhanced significantly at low pH; whilst obvious negative effect was observed in higher pH range. Below 12 mg/L HA, HA could obviously enhanced Eu(III) sorption to iron oxides, nevertheless Eu(III) sorption decreased steeply with increasing HA while HA exceeded 12 mg/L. The results were helpful for understanding radionuclides behaviors in natural environment.

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