Ce_3(PO_4)_4在酸性溶液加热条件下化学形态转化及机理研究

Study on chemical morphological conversion and mechanism of Ce_3(PO_4)_4 in the acid solution under the heating condition

磷酸高铈（Ce3（PO4）4）是一种难溶于水的化合物，本文测定磷酸高铈在常温pH=0．4的Ksp值为1～8×10^-34，但在测定过程中发现Ce3（PO4）4的溶解度受温度变化的影响较大，尤其在50℃以上时，Ce3（PO4）4饱和溶液体系中的Ce^4＋、PO4^3-和pH值均变化异常。根据测得的Ce^4＋、PO^3-浓度以及pH值，推断出50℃以上时Ce3（PO4）4转化为Ce（HPO4）2，并建立了相应的转化机理，测定出Ce（HPO4）2的Ksp为3～7×10^-13。

Ce3 （PO4）4 is a compound which dissolved difficultly. Its Ksp has not been reported yet. In this paper its Ksp was determined which was about 1 ～ 8 × 10^-34 under the room temperature. The solubihty of Ce3 （ PO4 ）4 changed greatly at different temporatures,espoctaUy when the temperature was above 50℃, pH and density of Ce^4＋ ,PO4^3- in saturated solution of Ce3 （PO4 ）4 changed greatly. According to density of Ce^4＋ ,PO4^3- and pH, it was infered that Ce3 （PO4 ）4 turn into Ce（ HPO4 ）2 above 50℃ ,Ksp of Ce （HPO4）2 was 3 ～7 × 10^-13 and corresponding transformation mechanism was set up.