二(2-乙基己基)二硫代次膦酸对硝酸溶液中Am3+和Eu3+的萃取

以正十二烷作稀释剂, 研究了二(2-乙基己基)二硫代次膦酸(D2EHDTPA)对HNO₃溶液中Am³⁺和Eu³⁺的萃取行为. 考察了酸度、 萃取剂及N{\mathrm{O}}_3^{-}浓度和皂化度对萃取的影响. 在考察的pH范围(2.5~4.5)内, D2EHDTPA萃取Am³⁺和Eu³⁺的分配比(D)随pH值增大而增加; pH=3.65时, 分离因子(SF_Am/Eu)值达到最大(4000). 随D2EHDTPA浓度的增加, D_Am和D_Eu值均增加. 斜率分析表明, D2EHDTPA萃取Am³⁺和Eu³⁺主要形成3:1和2:1型的萃合物. N{\mathrm{O}}_3^{-}未直接参与D2EHDTPA对Am³⁺和Eu³⁺的萃取反应. D2EHDTPA经NaOH皂化后, 萃取能力显著增强, SF_Am/Eu值提高到10⁴量级, 萃取容量约为理论值的60%. 此外, 使用高分辨质谱、 红外光谱和等温微量热滴定方法研究了D2EHDTPA与Eu³⁺的配位化学行为, 得到了金属离子与配体的组成比、 络合物稳定常数以及配位热力学参数ΔH, ΔS和ΔG值.

Extraction of Trivalent Americium and Europiumfrom Nitric Acid Solution with Di(2-ethylhexyl)dithiophosphinic Acid†

The extraction of Am³⁺ and Eu³⁺ from HNO₃ solution with di(2-ethylhexyl)dithiophosphinic acid(D2EHDTPA) were investigated using n-dodecane as diluent. Influences of acidity, ligand concentration, N{\mathrm{O}}_3^{-} concentration and saponification on the extraction of Am³⁺ and Eu³⁺ were evaluated. The distribution ratio values of both Am³⁺ and Eu³⁺ increased with increasing pH values from 2.5 to 4.5, and also with increasing the ligand concentration from 0.10 mol/L to 0.50 mol/L. The maximum value of separation factor(SF_Am/Eu) can reach 4000 at pH=3.65. Slope analyses indicated the main formation of 3:1 and 2:1 complexes of D2EHDTPA with Am³⁺ and Eu³⁺, respectively. The nitrate ion did not take part in the extraction reaction of D2EHDTPA with Am³⁺ or Eu³⁺. The extractability of D2EHDTPA was significantly enhanced through the saponification with NaOH solution. SF_Am/Eu values could be improved to the magnitude of 10⁴, and the extraction capacity was approximately 60% of the theoretical value. Furthermore, the complexation behaviors of D2EHDTPA with Eu³⁺ were also investigated by electrospray ionization mass spectrometry(ESI-MS), Fourier transform infrared(FTIR) and isothermal titration calorimetry(ITC). The composition and stability constants(lgβ) of the complex of D2EHDTPA with Eu³⁺, as well as the thermodynamic parameters(ΔH, ΔS and ΔG) were obtained.