【摘要】 采用批式法和溶剂萃取法,研究了Np在Np-水-膨润土平衡体系中的形态及价态分布以及pH值对形态及价态分布的影响。结果表明:在Np-水-膨润土平衡体系中,水相中的Np全部为Np（Ⅴ）,固相中的Np为Np（Ⅳ）、Np（Ⅴ）;pH=8⁹时,随着pH值的升高,固相中Np的比例升高,pH>9时,固相中Np的比例降低;随着CO3_<sup>2-浓度的升高,固相中Np的比例降低。PHREEQCI计算结果表明:pH<9时,Np在水相中的主要形态为NpO⁺₂,pH>9时NpO₂OH逐渐成为Np在水相中的主要形态;在高CO₃^2-浓度条件下,NpO₂（CO₃）₂^3-、NpO₂（CO₃）^5-₃是Np在水相中的主要形态;pH值对Np在水相和固相中的价态分布无影响。更多还原

【Abstract】 The speciation and valence distributions and effect of pH on the speciation and valence distributions of Np in the balanced system of Np-groundwater-bentonite were studied by batch experiments and solvent extraction methods.The results indicate that the valence of Np in groundwater is penta-valent state,and tetra-and penta-valent states were obtained on bentonite.With the increase of pH,the percentage of Np（Ⅴ）in bentonite increases at first and then decreases at pH>9.With the increase of CO₃^2-,the percentage of Np（Ⅴ）in bentonite decreases.The calculation results of PHREEQCI show that NpO⁺₂is the main speciation of Np at pH<9,and NpO₂ OH at pH>9.NpO₂（CO₃）₂^3-and NpO₂（CO₃）^5-₃are the main speciations of Np at high concentration CO₃^2-solution.The valence of Np is not affected by pH.更多还原