Efficient removal of thorium(IV) in aqueous solution using magnetic polyphosphazene (PSD-Fe₃O₄) microspheres

In this paper, a two-step precipitation polymerization method was used to prepare a magnetic poly(cyclotriphosphazene-co-3,3′-sulfonyl dianilide) (MPSD) as an adsorbent for the removal of the radioactive element thorium(IV) in aqueous solution. The magnetic material was characterized and analyzed by FTIR, XRD, SEM, BET and VSM. The experimental results showed that the adsorption capacity of MPSD was 286.7 mg/g when pH was 4.0. And the adsorption process fitted the Langmuir model (R² = 0.9991) and the pseudo-secondary kinetic model (R² = 0.9997). At the same time, the thermodynamic data indicated that the removal of thorium(IV) by MPSD microspheres was a spontaneous endothermic process.