Modeling and equilibrium studies on the recovery of praseodymium (III), dysprosium (III) and yttrium (III) using acidic cation exchange resin

In this research, the possibility of using hydrogenated Dowex 50WX8 resin for the recovery and separation of Pr(III), Dy(III) and Y(III) from aqueous nitrate solutions were carried out. Dowex 50WX8 adsorbent was characterized before and after sorption of metal ions using Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques. Sorption parameters were studied which included contact time, initial metal ion concentration, nitric acid concentration and adsorbent dose. The equilibrium time has been set at about 15.0 min. The experimental results showed that the sorption efficiency of metal ions under the investigated conditions decreased with increasing nitric acid concentration from 0.50 to 3.0 M. The maximum sorption capacity was found to be 30.0, 50.0 and 60.0 mg/g for Pr(III), DY(III) and Y(III), respectively. The desorption of Pr(III) from the loaded resin was achieved with 1.0 M citric acid at pH = 3 and found to be 58.0%. On the other hand, the maximum desorption of Dy(III) and Y(III) were achieved with 1.0 M nitric acid and 1.0 M ammonium carbonate, respectively. The sorption isotherm results indicated that Pr(III) and Y(II) fitted with nonlinear Langmuir isotherm model with regression factors 0.995 and 0.978, respectively; while, Dy(III) fitted with nonlinear Toth isotherm model with R(2) = 0.966. A Flow sheet which summarizes the sorption and desorption processes of Pr(III), DY(III) and Y(III) using Dowex 50WX8 from nitric acid solution under the optimum conditions is also given.