Highly efficient uranium(VI) removal from aqueous solution using poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl-ether) crosslinked microspheres

Poly(cyclotriphosphazene-co-4,4 '-diaminodiphenyl ether) crosslinked microspheres with active amino groups on the surface were prepared by one-step precipitation polymerization method. The as-prepared material were characterized by means of FTIR, XPS, XRD, EDS and SEM. The effects of pH, time of contact, dosage, initial concentration and temperature on the adsorption of uranium(VI) by the crosslinked microspheres were studied, and the adsorption mechanism was elucidated. Under the optimized adsorption conditions, the adsorption removal efficiency reached 97.03%. The experimental results fit the Langmuir isotherm model and adsorption processes comply with the pseudo-second-order kinetic model. Thermodynamic data revealed that the adsorption behavior of uranium(VI) on the microspheres was spontaneous and exothermic.