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Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g−1 for initial thorium(IV) concentration 50 mg L−1. When pH = 0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature. [ABSTRACT FROM AUTHOR]

Poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) microspheres (PZA) was based on hexachlorocyclotriphosphazene (HCCP) and 4,4′-diaminodiphenyl ether (ODA). It was synthesized via one-step precipitation method. The PZA microspheres were characterized by FT-IR, XPS, zeta potential and SEM/EDS. Through experimental research, PZA microspheres had the optimal adsorption performance with pH value 3.5, contact time of 60 min, thorium(IV) ions concentration of 30 mg L−1, and PZA microspheres of 10 mg. The maximum adsorption capacity of PZA microspheres for thorium(IV) was 29.04 mg g−1. The adsorption process could be described by the quasi-second order kinetic model and simulated by the Langmuir isotherm equation. [ABSTRACT FROM AUTHOR]