Rapid recovery of rare earth elements in industrial wastewater by CuFe2O4 synthesized from Cu sludge

This study systematically evaluates the recovery of rare earth elements(REEs) from aqueous solution and industrial wastewater using magnetic nanoparticles CuFe2O4. The industrially manufactured CuFe2O4displays a nonlinear isotherm for REEs adsorption, suggesting limiting binding sites on the CuFe2O4surface. The recovery of REEs increases significantly from 0.1% to 99.99% with increasing pH(2.29-8.15). At room temperature, the maxima recovery rates of Nd, La, and Ce are observed to be in a high capacity of 51.02, 42.02, and 40.16 mg/g, respectively. No significant attenuation of REE adsorption is observed with increasing NaCl concentration from 0.001 to 1.0 mol/L, showing high selectivity of REEs even in such high NaCl concentration matrix. In addition, desorption efficiency increases with the increasing concentration of HNO3in the range of 0.005-0.05 mol/L. When HNO3concentration is over 0.05 mol/L, the desorption efficiency can reach almost 100% in each batch experiment. Importantly, our results show that REEs can be sorbed and recycled from liquid crystal display(LCD) polishing wastewater, suggesting that CuFe2O4may be a good candidate in the efficient and rapid recovery of REEs from industrial wastewater.