Phosphate-based phosphor for the urban mining of lanthanides: a case study of samarium

The recycling of samarium ions (Sm3+) from the crystalline NaBaPO4-based phosphor to an optical glass was realized in a green and sustainable way. The solubility of NaBaPO4:Sm3+ luminescent material enables its complete dissolution in water with a small amount of phosphoric acid. By adjusting the pH to alkaline values, a precipitate was obtained. This precipitate was annealed with additional Na2CO3 and NH4H2PO4 and a transparent glass with orange-red fluorescence was obtained, indicating that Sm3+ was successfully recycled from the phosphor to the glass. The recovery efficiency of Sm3+ ions reaches 97.6%. Thus, a facile method to recycle a type of lanthanide from a phosphate-based phosphor for urban mining is reported in this work.