Mesoporous magnetic-polyaminated-chitosan nanocomposite for selective uranium removal: performance and mechanistic studies

Herein, highly efficient sorbent with chelating and ion-exchange properties was synthesized by assembling diethylenetriamine groups on the mesoporous hybrid magnetic-chitosan core-shell nanocomposite by heterogeneous nucleation. Different analytical methods were used to investigate the physicochemical and functional characteristics of the obtained material. The structural features were superparamagnetic (M-S: 30.73 emu g(-1)), specific surface area (similar to 75.27 m(2) g(-1)) with a dominant mesopores sizes (similar to 3-9 nm), high porosity (similar to 0.57 cm(3) g(-1)) and amine content (similar to 3.68 mmol g(-1)) and density (similar to 7.36 1/nm(2)). Uranyl ions sorption and selectivity characteristics were exploited. Isotherm fitted by Langmuir equation: the maximal sorption capacity was reported similar to 0.75 mmol(U) g(-1) at optimum pH(0) 3.5-5.0, and 298 K. Fast uptake kinetics (similar to 40 min) were suited using a pseudo-second order rate equation. The sorption activation energy was 20.43 kJ mol(-1). The half-sorption time (t(0.5)) was duplicated from 2.1 min to 4.2 min at 298 K and 323 K, respectively, indicating exothermicity. FTIR and XPS examinations demonstrated that the binding of UO22+ occurred at N- and O-functional groups via anion exchange, electrostatic attraction, chelation, and reduction mechanisms. Metal ions were recovered using acidified urea (0.25 M) with strong cycle performance and retention rate similar to 85.2% after eight sorption/desorption cycles. The sorbent was successfully evaluated for selective uranium sorption from multi-component acidic nuclear solution. Owing to such stability and reusability over multiple sorption cycles, the sorbent is promising in the field of uranium recovery. Finally, the sorption process was described using a new three-dimensional mathematical model for nonlinear quantitative description.