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  • Author or Editor: Xin Jin x
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Abstract  

Interfacial tension and interfacial adsorption parameters for benzyloctadecyldimethyl ammonium chloride (BODMAC) in three organic diluents were determined and interpreted. The interfacial activity of BODMAC is affected by the type of the organic diluent and the composition of the aqueous phase. The general order of interfacial activity of BODMAC is n-heptane (5% isobutanol) > carbon tetrachloride > chloroform. The effectiveness of adsorption of BODMAC is not only dependent on the organic diluent, but also on the inorganic electrolytes in the aqueous phase.

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Abstract

Two crystal samples, sodium 5-methylisophthalic acid monohydrate (C9H6O4Na2·H2O, s) and sodium isophthalic acid hemihydrate (C8H4O4Na2·1/2H2O, s), were prepared from water solution. Low-temperature heat capacities of the solid samples for sodium 5-methylisophthalic acid monohydrate (C9H6O4Na2·H2O, s) and sodium isophthalic acid hemihydrate (C8H4O4Na2·1/2H2O, s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 379 K. The experimental values of the molar heat capacities in the measured temperature region were fitted to a polynomial equation on molar heat capacities (C p,m) with the reduced temperatures (X), [X = f(T)], by a least-squares method. Thermodynamic functions of the compounds (C9H6O4Na2·H2O, s) and (C8H4O4Na2·1/2H2O, s) were calculated based on the fitted polynomial equation. The constant-volume energies of combustion of the compounds at T = 298.15 K were measured by a precise rotating-bomb combustion calorimeter to be Δc U(C9H6O4Na2·H2O, s) = −15428.49 ± 4.86 J g−1 and Δc U(C8H4O4Na2·1/2H2O, s) = −13484.25 ± 5.56 J g−1. The standard molar enthalpies of formation of the compounds were calculated to be Δ f H m θ (C9H6O4Na2·H2O, s) = −1458.740 ± 1.668 kJ mol−1 and Δ f H m θ(C8H4O4Na2·1/2H2O, s) = −2078.392 ± 1.605 kJ mol−1 in accordance with Hess’ law. The standard molar enthalpies of solution of the compounds, Δ sol H m θ(C9H6O4Na2·H2O, s) and Δ sol H m θ(C8H4O4Na2·1/2H2O, s), have been determined as being −11.917 ± 0.055 and −29.078 ± 0.069 kJ mol−1 by an RD496-2000 type microcalorimeter. In addition, the standard molar enthalpies of hydrated anion of the compounds were determined as being Δ f H m θ(C9H6O4 2−, aq) = −704.227 ± 1.674 kJ mol−1 and Δ f H m θ(C8H4O4Na2 2−, aq) = −1483.955 ± 1.612 kJ mol−1, from the standard molar enthalpies of solution and other auxiliary thermodynamic data through a thermochemical cycle.

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Summary  

The solvent extraction of uranium(VI) from concentrated chloride solutions by quaternary salt benzyloctadimethylammonium chloride (BODMAC, R4NCl) in three diluents was studied. The composition of the extracted species was R4N. UO2Cl3and (R4N)2 . UO2Cl4in the three diluents investigated. The dependence of the distribution ratios on the concentration of hydrochloric acid, extractant, salting-out agents and temperature was investigated. The extraction efficiency of BODMAC strongly depends on the nature of the diluent. The presence of Mg(SO4)2basically alters the sequence of diluent extraction efficiency.

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Abstract  

The mechanism of solvent extraction of gold(III) in hydrochloric acid media with quaternary ammonium salt octadecyl dimethyl benzyl ammonium chloride dissolved in chloroform was studied. The influences of temperature, NaCl and HCl concentraction on the extraction equilibrium were also investigated. The extraction reaction is exothermic ( H° = -28.53±0.15 kJ/mol) and log K ex = 5.47±0.04.

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Abstract  

The recovery of uranium(VI) from chloride solution using a liquid emulsion membrane (LEM) technique was studied. The emulsion is constituted by the quaternary salt of benzyloctadecyldimethyl ammonium chloride (BODMAC, R4NCl) as a carrier, kerosene as organic diluent, Span 80 as emulsifying agent and 0.5 mol/l Na2CO3 as stripping phase. The important variables affecting the LEM permeation process such as the concentrations of extractant, internal strip phase, types of organic diluent, and the presence of magnesium chloride or magnesium sulfate were investigated. It was found that, at a given condition, the maximum extraction rate of uranium(VI) reached 80%. The emulsion was stable at low pH in the presence of certain amounts of electrolytes such as NaCl and MgCl2.

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A rapid and simple analytical method based on matrix solid-phase dispersion combined with liquid chromatography coupled with tandem mass spectrometry has been developed by using bamboo charcoal as a dispersive adsorbent to simultaneously determine tetrabromobisphenol A (TBBPA) and hexabromocyclododecane diastereoisomers (HBCDs) in soil. The factors influencing the performance of the proposed method were investigated and optimized in detail, and the matrix effects were evaluated. Under optimum conditions, the proposed method showed good linearity within the range of 0.8–80 ng g−1 and limits of detection of 4–75 pg g−1 (S/N = 3). The satisfactory recoveries of TBBPA ranging from 72.8% to 92.5% and HBCDs ranging from 76.8% to 102.2% were obtained with relatively standard deviation (RSD) ranging from 3.4% to 9.8%. The proposed method has been successfully applied to analyze TBBPA and HBCDs in actual soil samples from the Yellow River Delta in China.

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Abstract  

The mechanism of solvent extraction of uranium(VI) from highly concentrated chloride solution with a quaternary ammonium salt, benzyloctadecyldimethylammonium chloride (BODMAC, R4NCl), dissolved in chloroform was studied. The compositions of the extracted species were R4N.UO2Cl3 and (R4N)2 .UO2Cl4. The extraction process is exothermic (ΔH° = -8.42±0.54 KJ/mol). Kex 1 and Kex 2 are calculated to be (3.62±0.55).10-2 and (1.06±0.17).103, respectively. In the extraction process, a W/O uranium(VI) rich emulsion solution has been formed between the organic and aqueous phases, its volume increased with the increase of BODMAC in the system. The influences of temperature, NaCl, MgCl2 and MgSO4 concentrations on the extraction equilibrium were also studied.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Ye Yu-xing, Hu Jin-xin, Huang Zi-lin, Shi Wei-qun, Wu Guang-min, Tang Hong-bin, Zhu Wen-bin, Wang Xiao-rong, Zhao Hu-gen, Dong Yu, Sheng Dong, Luo Fang-xiang, and Zhao Yan-ju

Abstract  

The partitioning of actinides from simulated high level liquid waste (HLLW) originated from the Purex process has been studied using a mixture of dihexyl N,N-diethylcarbamoylmethyl-phosphonate (DHDECMP) and tributylphosphonate (TBP) in kerosene (OK). The distribution ratios of actinides were investigated as a function of a number of parameters such as the concentration of nitric acid, salting-out reagent, Gd(III) in the aqueous phase, extractant in the organic phase, and temperature. The extraction complexes, extraction reaction constant k, and thermodynamic parameters H, G and S were determined. The extraction of actinides from simulated HLLW by DHDECMP-TBP/OK has been carried out using a miniature countercurrent centrifugal contactor. The results show that the removal efficiency of actinides is greater than 99.9%. A conceptual flowsheet for the removal of actinides from HLLW is proposed.

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