A study on the photo-reductive precipitation rate of europium sulfate from rare earth mixture by addition of hydrogen peroxide

Abstract

The influence of H2O2 on the photo-reductive precipitation of Eu3+ from a solution containing Sm3+, Eu3+ and Gd3+ was investigated. The solution contains isopropanol as a reduction agent, ammonium sulfate as a precipitation agent, and hydrogen peroxide as an acceleration agent of precipitation rate. A mercury lamp emitting a wavelength of 254 nm was used as a light source. Adding a small amount of H2O2 considerably increased the photo-reductive precipitation rate of Eu3+. OH radicals obtained from the photodecomposition of H2O2 oxidized isopropanol into the radical (CH3)2C’OH and the resulting radicals reduced Eu3+ rapidly. It was found that the organic radical has the ability to reduce only Eu3+ in the solution containing Sm3+, Eu3+ and Gd3+. The precipitation yields of Eu, Sm and Gd were about 99%, 10% and 4%, respectively. It was also found that the Sm and Gd were not photo-reduced and co-precipitated with Eu.