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Abstract  

In this paper, the sorption of Co(II) from aqueous solution to Ca-montmorillonite was studied under ambient conditions by using batch technique. The effects of contact time, solid content, pH, ionic strength and temperature on the sorption of Co(II) to Ca-montmorillonite was also investigated. The results indicated that the sorption of Co(II) was strongly dependent on pH values. The sorption was dependent on ionic strength at low pH values, but independent of ionic strength at high pH values. Outer-sphere surface complexes were formed on the surface of Ca-montmorillonite at low pH values, whereas inner-sphere surface complexes were formed at high pH values. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were used to simulate the sorption isotherms of Co(II) at three different temperatures. The thermodynamic parameters (ΔH 0, ΔS 0 and ΔG 0) were calculated from the temperature dependent sorption isotherms, and the results indicated that the sorption reaction of Co(II) to Ca-montmorillonite was an endothermic and spontaneous process. The high sorption capacity of Co(II) on Ca-montmorillonite suggests that the Ca-montmorillonite is a suitable material for the preconcentration and solidification of radiocobalt from aqueous solutions.

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Abstract  

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.

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Abstract  

The synergistic extraction of uranium(VI) from aqueous nitric acid solution with mixtures of bis(hexylsulfinyl)ethane (BHxSE) and petroleum sulfoxides (PSO) in 1,1,2,2-tetrachloroethane was studied. It has been found that the maximum synergistic extraction effect occurs when the molar ratio of PSO to BHxSE is close to 1. The composition of the complex of synergistic extraction was estimated as UO2(NO3)2 .BHxSE.PSO. The formation constant of the complex was equal to KBP = 4.23±0.03. The effects of extractant, nitric acid, salting-out agent, and complex anion concentrations and temperature on the extraction equilibrium of uranium(VI) were also studied.

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Abstract  

The kinetics and mechanism of uranium(VI) extraction from nitric acid solution by bis(octylsulfinyl)methane (BOSM) are studied with the method of stationary interface cell. The effects of temperature, extractant and nitric acid concentrations are discussed. The results showed that the extraction process is controlled by the following reaction: UO2(NO3)2 + BOSM(i)k1 k-1UO2(NO3)2BOSM(i). The variation of enthalpy associated with the extraction is -22.1±2.1 kJ/mol.

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Acta Chromatographica
Authors: Shaoshi Wen, Zixin Zhang, Xiaopeng Chen, Jinchang Liu, Haiyang Yu, Lifeng Han, Lijun Jin, Yi Zhang, and Tao Wang

Uric acid (UA) is the final product of purine metabolism in humans. Elevated serum UA levels lead to the development of hyperuricemia, gout, kidney diseases, and metabolic syndrome. Accurate determination of UA plays a critical role in clinical diagnosis and laboratory investigation. An ultra-performance liquid chromatography (UPLC) with ultraviolet detection method has been developed and validated for UA analysis. Separation was achieved by a Waters ethylene bridged hybrid (BEH) Amide column (50 mm × 2.1 mm i.d., 1.7 μm) with acetonitrile and 0.1% acetic acid in deionized water in the proportion of 90 to 10 (v/v) as the mobile phase. The limit of detection and limit of quantification were 0.09 and 0.18 μmol/L, respectively. The method was validated by evaluating recovery (98.37–104.20%), accuracy (0.47–0.90%), and precision (1.24–1.81% for intra-batch and 1.76–3.98% for inter-batch). This method was then applied to UA determination in rat serum of hyperuricemia model. The results from UPLC, high-performance liquid chromatography (HPLC), and uric acid kits (phosphor-tungstic acid-based kit and uricase-based kit) were compared. The UPLC results were in very good agreement with HPLC. The developed method could be employed as a useful tool for the determination of UA in biofluids.

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