Solubility Polytherms from 25 to 75°C for Aqueous Systems of Lanthanum or Gadolinium Iodide with Potassium or Ammonium Iodide

Solubility in the (La,Gd)I3-(K,NH4)I-H2O systems was studied by the isothermal method over the temperature range 25-75°C. The solubility isotherms at 25, 50, and 75°C have a eutonic character. Regions of crystallization were determined for LnI3 · nH2O, where Ln = La or Gd and n = 3, 4, 6, or 9. Raising the concentration of a lanthanide iodide has a salting-out effect on potassium and ammonium iodides.