Manganese ferrite/porous graphite carbon nitride composites for U(VI) adsorption from aqueous solutions

Manganese ferrite/porous graphite carbon nitride composites (MnFe2O4/porous g-C3N4[PCN]) were synthesized by template-assisted thermal polymerization and hydrothermal method and applied for high adsorption of U(VI) from aqueous solution. Results indicated that the maximum adsorption capacity of MnFe2O4/PCN (MPCN) was 367.9 mg g−1 under optimum conditions (pH = 5, t = 15 min, and T = 308 K), which was higher than that of g-C3N4 (185.1 mg g−1). Adsorption was well fitted with Langmuir isotherm model and pseudo-second-order kinetic equation. Thermodynamic analysis showed that adsorption is an endothermic, spontaneous process. X-ray photoelectron spectra revealed that amino and metal oxygen groups are involved in the complexing adsorption of uranium. Adsorption efficiency remained 92.5% after five adsorption–desorption cycles. The results of this paper indicated that MnFe2O4/PCN composites can be efficiently used as an ideal material for U(VI) adsorption.