Complex formation of trace elements in geochemical systems—VI: Study on the formation of hydroxo fluoro mixed ligand complexes of the lanthanide elements in fluorite bearing system

The complexation of the rare elements Ce, Eu, Tb and Yb in fluorite bearing model solution of the pH 5–9 and the pF 2–5 has been studied by means of the distribution method. Hydroxofluoro mixed ligand complexes were found to be the most important species formed at pH 7 and pF 3 which are the relevant values of hydrothermal fluorite bearing solutions. The stability constants and the distribution of these complexes as a function of pH and pF were determined.