Solid-liquid extraction for yttrium recovery using porous polymeric resin (XAD-7) functionalized with D2EHPA

Abstract

The recovery of yttrium is proposed by applying a solid–liquid extraction process using di-2-ethyl hexylphosphoric acid (D2EHPA) as extracting agent. The extracting agents were supported on a macro porous polymeric resin XAD-7 (solid phase). Yttrium ions extraction and discharge tests were performed, firstly from a synthetic aqueous solution of 100 mg/L Y (liquid phase) at 25 °C with stirring. The effects of pH of aqueous solutions bearing yttrium, volume fraction of extracting agents and the solid/liquid (S/L) ratio on the yttrium recovery were studied. The most favorable conditions for yttrium ions extraction are: 20 vol% D2EHPA functionalized resin, pH = 1.5 and an S/L ratio of 10 mg/mL. The discharge of yttrium ions was done under the same conditions of extraction stage, using a 2 mol/L [H2SO4] as stripping solution. Up to 80 % yttrium is extracted, while 75 % yttrium is recovered in the striping solution. In all experiments, the reaction equilibrium is reached after 20 min, and the kinetics for the extraction stage was determined as a second-order model. Also, experiments were carried out to discharge the yttrium-loaded resins, and it has been determined that the best pH value to strip the Y ions is 1.5. Cyclic tests of extraction and discharge for yttrium ions show that the functionalized resin can work at least five cycles without decreasing its efficiency. Finally, the proposed process was tested in a real solution with Y ions from a waste fluorescent lamp powder leached in H2SO4, demonstrating the ability to effectively recover yttrium, separating it from various metals from the studied residue.