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  • Author or Editor: Zhang Pilu x
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Abstract  

The influence of acidity, hydroxylamine concentration, temperature, and time on the pretreatment effect have been studied. An approximate reaction rate equation of the systems studied has been obtained as follows:r=K[RuNO]2.5[H2NOH]1.3[HNO3]–1.0. The pretreatment effect is obvious at low acidity. which makes the Ru distribution coefficient decrease by ten times.

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Abstract  

The distributions of the chemical states of131I,132I,133I,134I and135I produced by the spontaneous fission of252Cf were investigated by the method of fractional precipitation separation in 6M NH4OH solution followed by measurement of the X-ray spectrum of the samples with a Ge(Li) detector. The iodine fission fragments were separately collected in the matrices of NaNO3, NaCl, dehydrated sodium sulfate, CH3COONa·3H2O, Na3H2IO6, KI and NaIO3 crystals. The results showed that the distribution of the chemical states was the function of the collection time, the nature of matrix materials and the type of iodine isotopes. The relative amount of the reduced states of134I decreased with the increase of collection time in the matrix of NaNO3. The ratio of the amount of reduced states to the total amount of the134I was the highest (50.4%) in NaCl matrix and the lowest (9.4%) in Na3H2IO6 matrix. The relative quantities of reduced states of135I were the highest (58.5% and 97.7%) and that of134I were the lowest (16.9% and 63.1%) in matrices of NaNO3 and NaCl, respectively.

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Abstract  

The distribution of the chemical states of tellurium isotopes produced by252Cf spontaneous fission, collected separately in the matrixes of NaCl, Kl, NaF, CH3COONa·3H2O, Na2SO4 and NaNO3 crystals have been investigated. Two chemical states of tellurium isotopes maintained in these matrixes are Te(IV) and Te(VI). The relationships between the distribution of the chemical states of tellurium isotopes and the produced mode of tellurium, the chemical properties of collection matrixes, the time for collecting fission fragments are studied and the possible mechanism of the interactions of the fission products and the matrixes is discussed. The results show that the distribution of chemical states of tellurium isotopes depends on the chemical properties of the collection matrixes mainly.

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Abstract  

The reduction kinetics of pertechnetate by thiocyanate in perchloric acid is studied by spectrophotometric method. The effect of the concentrations of pertechnetate, hydrogen ion and thiocyanate on the reaction rate is investigated. The kinetic expression at 25°C is: −dC VII/dt=(2.2±0.4)·10−3 [TcO4 ]1.1 [H+]3.2 [SCN]3.3 The effect of temperature on the reaction rate is studied. The activation energy is 91 kJ/mol. The possible mechanism of the reaction is discussed.

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