皂化酸性磷酸酯萃取稀土离子过程中有机相的FTIR光谱表征

FTIR Characterization of Extracted Organic Phase in Saponified Organophosphoric Acid System Containing Lanthanide

研究了不同浓碱皂化的Ｄ２ＥＨＰＡ－正庚烷体系萃取一系列稀土离子（Ｌａ￣（３＋）→Ｌｕ￣（３＋），放射性的Ｐｍ 除外）过程中有机相的ＦＴＩＲ光谱变化规律．结果表明：Ｄ２ＥＨＰＡ萃取稀土离子后，Ｐ＝Ｏ基团的红外吸收频率降低，吸收强度升高，说明Ｐ＝Ｏ基团与稀土离子发生配位；红外光谱研究结果还表明：不同稀土离子与Ｐ＝Ｏ配位能力有差别，从Ｌａ￣（３＋）→Ｓｍ￣（３＋）配位能力依次增大，从Ｓｍ￣（３＋）→Ｌｕ￣（３＋）则呈下降趋势，对同一个稀土离子来说，随着有机相中稀土离子含量的增加，有机相微乳液中Ｈ＿２Ｏ的含量减小，萃取过程伴随有破乳发生．

FTIR spectroscopy was used to investigate the coordination interaction of D2EHPA [di(2-ethylhexyl) phosphoric acid] with lathanide(Ⅲ)series(La(3+)→Lu(3+), except radioactive promethium ). P=O band shifts to the lower frequency when D2EHPA is saponified with concentrated basic solutions (NaOH,KOH or NH3· H2O).The coordination sequence of Na+,K+ and NH with P=O group is NH+ >Na+ >K+. The frequency of P=Oband in the extracted organic phase containing RE-D2EHPA complexes shifts to the lower wavenumbers as the lanthanide(Ⅲ)loading increases in organic phase,and the intensity of P=O band increases. FTIR spectra results show that the coordination ability of lanthanide(Ⅲ)series with P=O group is as follows:La3+<Ce3+<Pr3+<Nd3+<Sm3+>Eu3+>…>Lu3+, namely,the complexation intreaction of Sm3+ with P=O is the strongest.In addition,the w/o microemulsion was gradually destructed with the entrance RE3+into the organic phase.