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  • Author or Editor: E. Schmid x
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Abstract  

We present a new gluing construction for semimodular lattices, related to the Hall-Dilworth construction

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Abstract  

The nitrate salt solution of the secondary amine Amberlite LA-1 in organic solvents extracts uranium(IV) from aqueous nitric acid solutions. The distribution ratio of uranium(IV) reaches a maximum at an equilibrium nitric acid concentration of 8.5M in the aqueous phase. Addition of n-octanol to the organic phase decreases, and the addition of nitrate to the aqueous phase increases the uranium(IV) distribution ratio. The extraction of uranium(IV) is fast and the equilibrium distribution is reached within less than one minute. At low uranium(IV) concentrations (<6·10−3 M) the distribution ratio is independent of the uranium(IV) concentration. At high uranium(IV) loadings of the organic phase an extrapolation gives a mole ratio of amine: uranium(IV)=2∶1. A double logarithmic plot of the dependence of the uranium(IV) distribution ratio vs. the LA-1 concentration in the organic phase gives a curve with a slope of two when polar diluents for LA-1 are used. This slope of two and the shapes of the absorption spectra of the organic phase from 400 to 700 nm make it very probable that uranium(IV) exists in the organic phase as a hexanitrato complex.

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Abstract  

The distribution of uranium(IV) between aqueous nitric acid solutions and solutions of the nitrate salt of the primary amine Primene JM-T in various diluents is described. The influence of the concentration of the acid, nitrate and perchlorate in the aqueous phase is studied, taking into account the complex composition of uranium(IV) in the aqueous phase and the acid content of the organic phase. The uranium(IV) extraction may be explained by the competition between metal complex and nitric acid for the extracting agent. The absorption spectra of the organic phase and the results of maximum loading experiments indicate that the uranium(IV) species in the organic phase is the bis-alkylammonium-hexanitrato-uranium(IV) complex [(RNH3)2U(NO3)6].

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Abstract  

The influence of ethanol on the distribution of thorium(IV) and uranium(VI) between solutions of nitric acid and solutions of Amberlite LA-2, Trilaurylamine and Aliquat 336-nitrate has been investigated. Increasing amounts of nitric acid and ethanol in the aqueous phase cause an increase of the acid concentration in the organic phase. This concentration can be calculated by a given formula for Amberlite LA-2. The distribution of acid and ethanol is discussed. The distribution ratios of thorium(IV) and uranium(VI) are changed by adding ethanol to the liquid-liquid-system. This can be explained by the shift of the equilibrium of the metal nitrate complexes and by the enhanced extraction of acid.

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Abstract  

The influence of acetone on the extraction of Th(IV) and U(VI) from aqueous solutions of nitric acid by solutions of Amberlite LA-2 and trilaurylamine in cyclohexane has been investigated. The partition of nitric acid and acetone between the two phases is discussed. The change of the distribution ratios of Th(IV) and U(VI) by adding acetone to the liquid-liquid-system is explained by the shift of the equilibrium of the metal nitrate complexes and by the increase of the concentration of nitric acid in the organic phase.

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Abstract  

The distribution of acid, water, methanol, ethanol and acetone between mixed aqueous-organic nitric acid solutions and solutions of trilaurylammoniumnitrate in cyclohexane has been investigated. The distribution of acid rises with increasing concentrations of nitric acid, methanol, ethanol and acetone in the mixed aqueous-organic phase. The effect of the organic additives in increasing the distribution of the acid is methanol<ethanol<acetone. The concentration of nitric acid in the organic phase can be calculated by a formula similar to that describing the extraction from pure aqueous solutions. The distribution curves of water, methanol and ethanol resemble each other, all of them showing a minimum, when the distribution ration is plotted versus the nitric acid concentration in the mixed aqueous-organic phase. The acetone distribution decreases steadily with increasing nitric acid concentration. The shape of the curves is briefly discussed.

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Abstract  

The influence of methanol on the distribution of thorium(IV) and uranium(VI) between aqueous solutions of nitric acid and solutions of Amberlite LA-2, trilaurylamine and Aliquat-336-nitrate has been investigated. The amount of acid in the organic phase increases with increasing concentration of nitric acid and methanol in the aqueous phase. The concentration of acid in the organic phase can be calculated by a given formula for Amberlite LA-2. The distribution of methanol is discussed. The distribution of thorium(IV) and uranium(VI) changes, when methanol is added. This is explained by the shift of the equilibrium of the metal complex and by the enhanced extraction of acid.

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Abstract  

The heat capacities of eight chlorine boracites T3B7O13Cl (T=Cr, Mn, Fe, Co, Ni, Cu, Zn or Mg) have been measured in the temperature range 2 to 100 K. Magnetic phase transitions occur below 20 K in the compounds studied except in the two non-magnetic substances Zn3B7O13Cl and Mg3B7O13Cl. The magnetic specific heat capacities give information on magnetic ground state of the transition metals and the entropy related to the phase transitions.

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