Recovery of rare earth elements from waste phosphors using phosphonic acid-functionalized silica adsorbent

Recovery of rare earth elements from secondary sources is crucial to promote environmental sustainability and ensure the responsible utilization of natural resources. In this study, we showed a potential application of a silica-based adsorbent with immobilized fragments of aminobis(methylenephosphonic acid) for selective recovery of rare earth elements from acidic solutions, such as leaching solution of red lamp phosphor waste. The adsorption behavior of the material was studied in the dispersive solid phase extraction mode from model aqueous solutions that had an excess of 22 interfering ions in 0.5 mol/L NaCl. The results demonstrate reversible adsorption and outstanding kinetic characteristics of the adsorbent. The complete absorption of 14 rare earth elements occurs in less than 5 min under acidic conditions (with pH above 2.0). This method resulted in a 100-fold increase in the content of rare earth elements extracted from leachate.