Investigation of the high U(VI) adsorption properties of phosphoric acid-functionalized heteroatoms-doped carbon materials

In this study, polyphosphazene microspheres (PZS) was prepared by reaction under ultrasonic conditions using hexachlorocyclotriphosphazene (HCCP) and 4,4-dihydroxydiphenyl sulfone (BPS) as raw materials. Phosphoric acid-functionalized microporous carbon materials (denoted as CS-PO4) was further derived from PZS by carbonization and functionalization. The structure of CS-PO4 was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The adsorption properties of CS-PO4 for uranyl ions in aqueous solution under different conditions (namely pH, contact time, initial concentration and temperature) were investigated. The results indicate that the optimum pH for adsorption was 6 while the equilibrium time was about 40 min. The maximum adsorption capacity was about 1029.8 mg/g, as calculated by the Langmuir model. The comprehensive analysis of the adsorption thermodynamics and kinetics show that the CS-PO4 can be used to adsorb U(VI) effectively in solution. © 2020 Elsevier Masson SAS