Leaching Kinetics of Yttrium and Europium Oxides from Waste Phosphor Powder

Phosphor powder sample was characterized, and the leaching kinetics of yttrium, and europium in hydrochloric acid were investigated. Under optimized leaching conditions, 98% Y and 97% Eu were extracted, and a reaction curve was generated using the percentage of extraction as a function of time and temperature. Based on R 2 values, shrinking spherical particle and shrinking core model were not applicable. SEM analysis also confirmed shrinking core behavior was not applicable due to the lack of core–shells in the leach residue. The kinetic data were best fitted by a logarithmic rate expression of the empirical model. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298–343 K.