~(99)Tc在Fe,Fe_2O_3和Fe_3O_4上的吸附行为研究
Study on Adsorption of ~(99)Tc on Fe, Fe_2O_3 and Fe_3O_4
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摘要: 用批式法研究了大气条件下99Tc在Fe,Fe2O3和Fe3O4上的吸附行为,考察了吸附平衡后溶液中99Tc的存在价态。实验结果表明:随着溶液pH值(5~12)、CO2-3浓度(1×10-8~1×10-2mol/L)的增大,99Tc在Fe上的吸附比减小;溶液pH值、CO2-3浓度的变化基本不影响99Tc在Fe2O3和Fe3O4上的吸附;99Tc在这3种吸附材料上的吸附行为均可用Freundlich吸附等温式表示;当Fe作吸附材料时,吸附平衡后99Tc主要以Tc(Ⅳ)的形式被吸附,当Fe2O3和Fe3O4作为吸附材料时,99Tc主要以Tc(Ⅶ)的形式被吸附。Abstract: The absorption behavior of ~(99)Tc on Fe, Fe_2O_3 and Fe_3O_4 powders from aqueous ~(99)TcO~-_4 (solutions) is studied by batch method in atmospheric conditions. After the adsorption reaches (equilibrium), the valence state of ~(99)Tc in the aqueous solution is examined by extraction with tetraphenylarsonium chloride. The experimental results show that the adsorption ratio of ~(99)Tc on iron powders decreases with the increase of pH (in the range of 5~8) and of CO~(2-)_3 concentration (in the range of 1×10~(-8)~1×10~(-2) mol/L). In opposite, the two factors have no significant influence on the absorption of ~(99)Tc on both Fe_2O_3 and Fe_3O_4 powders. The adsorption isotherms of ~(99)TcO~-_4 on Fe, Fe_2O_3 and Fe_3O_4 powders can be well described by the Freudlich's equation. The major valence state of ~(99)Tc is deduced to be Tc(Ⅳ) when iron powders is used as the absorbent. In the case of Fe_2O_3 or Fe_3O_4 as an absorbent, the ~(99)Tc remains as the TcO~-_4 form.