【摘要】 结合静态批实验研究pH、离子强度对放射性核素63 Ni(Ⅱ)在高岭土上的吸附行为的影响,同时采用扩散层模型与FITEQL 4.0软件对吸附数据进行拟合研究。宏观的实验结果表明:放射性核素63 Ni(Ⅱ)在高岭土上的吸附在pH<8.5条件下受离子强度的影响,而在pH>8.5时不受离子强度的影响;放射性核素63 Ni(Ⅱ)的吸附在低pH条件下以阳离子交换和外层络合作用占主导,而在高pH时以内层络合作用为吸附的主要机理。研究结果对于评估放射性核素63 Ni(Ⅱ)在高岭土的吸附行为和形态分布、准确预测其在环境介质中的迁移与转化行为具有极其重要的现实意义。更多还原

【Abstract】 The uptake of radionuclide on kaolinite has been investigated extensively due to its low penetrability and high sorption capacity.Herein,kaolinite was characterized by acid-base titration.The uptake behavior of 63Ni(Ⅱ) on kaolinite as a function of pH and ionic strength was studied by using batch technique under ambient conditions.The experimental data of 63Ni(Ⅱ) sorption on kaolinite was obtained using the diffuse layer model combined with the FITEQL 4.0 program and the consecutive acidity constants as pKa were optimized simultaneously.The uptake of 63Ni(Ⅱ) on kaolinite contains ≡XONi+ species at low pH values and ≡YONi+ species at high pH values.Macroscopic experiment results show that the uptake of 63Ni(Ⅱ) is greatly dependent on ionic strength at pH<8.5,and independent of ionic strength at pH>8.5.At low pH,the uptake of 63Ni(Ⅱ) is predominated by ion exchange and/or outer-sphere surface complexation with Al3+/H+ on kaolinite surface,whereas inner-sphere surface complexation is the primary uptake mechanism at high pH values.The macroscopic uptake data of 63Ni(Ⅱ) surface speciation at the kaolinite/water interface should be significant to evaluate and predict the migration and uptake behavior of 63Ni(Ⅱ) in environment mediums.更多还原