Preparation and characterization of a solvent impregnated resin for the recovery of rare earth elements from waste recycling solutions.

A new synthetically available resin SIR-SiO2@L was obtained by impregnating hydrophobic silica gel (SiO2@) with 2-(diphenylphosphoryl)-N,N-dioctylacetamide (L). Characterization by BET, FTIR, SEM/EMPA, TGA, and contact angle (CA) measurements confirmed the successful synthesis and surface modification of the SiO2@ and SIR-SiO2@L. The bulk density of SIR-SiO₂@L is 0.79 g/cm³. The interaction characteristics of the SIR-SiO2@L resin with Nd(NO3)3 were studied using IR spectroscopy. The sorption characteristics of the SIR-SiO2@L towards some REE were studied using the extraction chromatography method. In a 1.0 mol/L NH4NO3 solution, the dynamic distribution coefficients were Kd(Y) = 250, Kd(La) = 860, Kd(Nd) = 970, Kd(Pr) = 1300, Kd(Sm) = 1150, Kd(Ho) = 310, and Kd(Dy) = 450 mL/g. Using neodymium as an example, the sorption properties of SIR-SiO2@L were compared with those of known analogs - SIR-LPS-500 L and TRU (TrisKem). The Kd values for Nd are 167, 187 and 410 mL/g for the TRU, SIR-LPS-500 L and SIR-SiO2@L resins, respectively. The feasibility of efficiently separating La/Y and Nd/Dy mixtures into individual components in elution mode using the SIR-SiO2@L sorbent was demonstrated.