Abstract
•PMNM (porous magnetic Ni0.6Fe2.4O4 micro-particles) were synthesized by a simple method.•The adsorbent shows relatively high adsorption capacity for the removal of U(VI).•The U(VI) adsorbed onto PMNM could be easily isolated by magnetic separation.•The adsorption kinetics could be fitted well by the pseudo-second-order model.•The U(VI) adsorption onto PMNM is endothermic and spontaneous.
Porous magnetic Ni0.6Fe2.4O4 micro-particles (PMNM) with great adsorption performance for U(VI) removal were successfully obtained by calcining Ni0.6Fe2.4C2O4·2H2O precursor. The as-obtained PMNM exhibit a typical porous nature with uniform pore size distribution. The adsorption of U(VI) onto PMNM reaches equilibrium in 2 h with a maximum adsorption capacity of 189.04mg/g at 318.15K, which can be ascribed to the mesoporous texture and abundant adsorption sites. The adsorption can be influenced by the pH values of solution, while no ionic strength effect was observed, indicating an inner-sphere surface complexation mechanism. The adsorption process can be well described by pseudo-second-order kinetic model and the Freundlich isotherm model, indicating a multilayer adsorption process. Moreover, the mean free energy (E) calculated from D–R isotherm model suggests a physical adsorption process, implemented via the electrostatic attraction. Thermodynamic analyses indicate that the adsorption process is entropy-driven endothermic and spontaneous in nature. Furthermore, magnetic property of PMNM makes U(VI)-loaded PMNM be easily separated from aqueous solution by using an external magnet. These results clearly indicate that the PMNM could be used as a candidate for efficient removal of U(VI) from aqueous solutions.
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