Solid-Solid Separation of Fluorescent Powders by Liquid-Liquid Extraction Using Aqueous and Organic Phases

Abstract

Two-step liquid-liquid extraction methods using aqueous and organic phases for separation of red (Y2O3: Eu 3+), blue (BaMgAl10O17: Eu 2+) and green (CeMgAl10O17: Tb 3+) fine fluorescent powders were proposed in this paper. At first, the blue powder was extracted selectively into heptane phase using a chelating agent, 2-thenoyltrifluoroacetone (HTTA, CF3COCH2COC4H3S) under alkaline pH condition. Then, chloroform was used for extracting the green powder into the chloroform phase. The red powder separating from the green powder remained in aqueous phase with a depressant, potassium sodium tartrate tetrahydrate (PST, KNaC4H4O6•4H2O). The powders could be well separated in terms of their grade and recovery. The results suggested directions for future research into the recycling of fluorescent powders from fluorescent lights.