The kinetics of ion exchange of Zr/Sn(IV) phosphonate–phosphate hybrid ion exchange materials have been studied with several types of ions of specific interest to nuclear fuel recycling including Nd3+ at 4.5 and 43 mM and NpO2+ at 2.9 mM spanning multiple HNO3 concentrations. In most cases, the equilibrium was reached in less than 12 h. The ion exchange behavior followed that of pseudo first-order adsorption with rates ranging from 0.430–4.10 h−1 to 0.290–0.435 h−1 for Nd3+ and NpO2+, respectively. A separation with both Nd3+ and NpO2+ present was performed, resulting in separation factors of 1.9–12, 1.7–6.6, and 2.0–5.7 at 1 × 10−1, 1 × 10−2, and 1 × 10−3 M HNO3, respectively.
