水溶液中稳定四价镧系化合物的研究(Ⅰ)——在六偏磷酸钠水溶液中稳定Tb(Ⅳ)

STABILIZATION OF TETRAVALENT LANTHANIDE IN AQUEOUS SOLUTION (Ⅰ)——STABILIZATION OF TERBIUM(Ⅳ) IN AQUEOUS HEXAMATEPHOSPHATE SOLUTION

已知镧系元素中铈、镨、钕、铽及镝可形成四价化合物。然而除铈以外,其余的四价化合物多数是用干法或由非水介质中获得的。由标准电极电位E_(M4)^(0)+/M^(3)+可知,铈以外的四价镧系离子在水溶液中很难稳定存在,除非形成足够稳定的络合物。以前曾有过从水溶液中获得Pr(Ⅳ),Nd(Ⅳ)及Tb(Ⅳ)化合物的报导,但均未被后人所重复。

The stabilization of terbium(Ⅳ) with hexametaphosphate in aqueous solution has been studied in the paper. A stable solution of terbium( Ⅳ ) with red brown color was obtained, by dissolving the hydrated oxide of terbi-um(Ⅳ) in sodium hexametaphosphate solution. This solution has a broad band absorption near 375nm, which is considered to be, one of characteristics of terbium(Ⅳ) compounds. The color of the solution of terbium(Ⅳ) will remain unchanged for a long time at 6<pH<13. The red brown solution of terbium(Ⅳ) possesses some colloid properties, i. e. Tyndal effect, electrophoresis and flocculation by adding a small amount of electrolyte. It is confirmed by chemical analysis that the flocculation product is Tb(Ⅳ) hydrated oxide. Thus it can be seen that the stabilization of Tb(Ⅳ) in aqueous solution is due to the formation of colloid solution.