在原碲酸盐水溶液中用臭氧氧化Pr(Ⅲ)和Tb(Ⅲ)

在原碲酸盐水溶液中,用臭氧氧化Pr(Ⅲ)和Tb(Ⅲ),得到了相应的四价化合物。由紫外和可见吸收光谱证明了溶液中Pr(Ⅳ)和Tb(Ⅳ)的存在。动力学研究发现Pr(Ⅳ)和Tb(Ⅳ)在碱性溶液中的还原反应是拟一级反应,其半衰期分别为18′14″和2.65天。测定了有络合剂存在时,不同浓度Tb(Ⅳ)溶液的电位,测得Tb(Ⅳ)/Tb(Ⅲ)电对在该条件下的克式量电位是+0.953V。

THE OXIDATION OF TRIVALENT PRASEODYMIUM AND TERBIUM WITH OZONE IN AQUEOUS ORTHO-TELLURATE SOLUTION

It has been presented in this paper that Pr (Ⅳ) and Tb(Ⅳ) were prepared by oxidation of the corresponding trivalent species with ozone in aqueous ortho-tellurate solution. By means of ultraviolet and visible absorption spectroscopy, the existence of Pr(Ⅳ) and Tb(Ⅳ) in the solution has been proved. The characteristic absorption peaks for Pr(Ⅳ) are at 280, 447, 475 and 490nm, and that for Tb(Ⅳ) is at 360 nm. Kinetic studies on the solutions of Pr(Ⅳ) and Tb(Ⅳ) showed that the reductions of Pr(Ⅳ) and Tb(Ⅳ) in alkali aqueous solutions are pseudofirst-order reactions. The half-lives of Pr(Ⅳ) and Tb(Ⅳ) in these solutions are 18′14° and 2.65 days respectively. The potentials of the solutions which contained various concentrations of Tb(Ⅳ) in the presence of the complexing reagent have been measured and it has been found that under this condition the formal potential of the Tb(Ⅳ)/Tb (Ⅲ) couple is +0.953 V.