Cyanex 923萃取稀土元素的温度效应和热力学函数

Temperature Effect of Extraction of Rare Earth Elements and Thermodynamic Functions with Cyanex 923

研究了温度对纯化和未纯化Cyanex 923萃取Y和镧系元素硝酸盐的影响,计算了萃取反应平衡常数和热力学函数,并探讨了它们与稀土原子序数的递变规律。结果表明:温度由低到高,两者的分配比D都逐渐下降,表明该萃取体系为放热反应。未纯化Cyanex 923比纯化的萃取热效应要小,随原子序数增大,其差别逐渐增大。利用纯化的Cyanex 923随温度变化的规律有可能使Y与镧系元素分离。热力学函数对原子序数作图,可以看到"四分组效应"的存在。

The effect of the temperature on extraction of yttrium and lanthanide nitrates with purification or not purified Cyanex 923 was studied. The equilibrium constant of the extraction and thermodynamic functions were calculated, and the grading rule with the atomic number of rare earths was discussed. The results showed that with the temperature increasing from low to high, the distribution ratio （D） of the two gradually declined, showing that the extraction system was as the exothermic reaction. The heating effect without purification Cyanex 923 was less than that of purified extraction, and its difference increased graduaUy with the atomic number increased. Using the purified Cyanex 923 along with the rule of temperature change is likely to make Y and La separation. ＂Tetrad effect＂ can be seen from the thermodynamic functions to atomic number drawings.