Optimization of intensified leaching and selective recovery of Y and Eu from waste cathode ray tube phosphor

[Display omitted] •Optimization of leaching of Y and Eu from waste CRT phosphor using RSM.•ANOVA showed the significant effect of temperature and acid concentration.•Complete leaching of Y and Eu was achieved under optimum conditions.•Selective recovery of Y and Eu using precipitation at low solution pH.•Y and Eu from leaching solution were recovered as REE(PO4). The optimization study of rare earth elements (REEs) leaching from electronic waste is imperative for industrial-scale development with cost- and energy-efficient processing. Response surface methodology (RSM) with the principle of central composite design (CCD) was utilized to optimize the Y and Eu leaching process from waste cathode ray tube (CRT) phosphor in subcritical water extraction. The analysis of variance (ANOVA) demonstrated that acid concentration and leaching temperature had a significant effect on the leaching efficiency of Y and Eu in subcritical water extraction. The obtained optimum conditions of Y and Eu leaching from waste CRT phosphor were 1.15 mol/L H2SO4 solution as the leaching agent, 166 ± 1 °C, for 27 min in subcritical water at a 20 g/L of solid to liquid (S/L) ratio. The experiment under optimum conditions resulted in 99.07 % and 99.62 % leaching efficiency of Y and Eu, respectively, which had a relative error of less than 1 % from the value predicted by the model. Selective separation of Y and Eu from the leaching solution was carried out as well and it resulted in 87.72 % and 95.11 % recovery of Y and Eu, respectively. The recovery product consists mainly of REE(PO4). This study could be the alternative process for electronic waste utilization as the secondary resources of valuable rare metals promoting the circular economy.