Effect of temperature on the extraction of rare earth elements by alkylammonium salts

The extraction of rare earth elements in the cerium subgroup by tri-n-octylammonium nitrates in the temperature range 283-3280K is discussed. The effects of the temperature dependence of the distribution coefficients on the nature of the extracted metal, the nature and concentration of the salting out agents, and additions of complexone to the aqueous phase were studied. In the majority of systems considered the distribution coefficients and separation factors decreased with an increase in temperature. The temperature dependence are given in the form D = a + b/sup ./ (1/T). The results are interpreted qualitatively, taking into account the contributions of the different factors to the enthalpy change during the extraction reaction