Uranium extraction using magnetic nano-based particles of diethylenetriamine-functionalized chitosan: Equilibrium and kinetic studies

Magnetic nano-based particles of diethylenetriamine-functionalized chitosan have been synthesized before being characterized by elemental analysis, FT-IR spectroscopy, XRD, AFM, TEM and VSM analysis. Uranium adsorption (from synthetic solutions) has been investigated in batch systems. The effects of different experimental parameters such as initial solution pH (controlled with sulfuric acid), equilibration time, initial uranium concentration and temperature on sorption performance have been determined. The nano-based particles, with size in the range 10-30 nm, are super-paramagnetic. The kinetic data can be efficiently modelled using the pseudo-second-order equation. The Langmuir and the Dubinin-Radushkevich (D-R) equations fit well sorption isotherms. The value of activation energy (E-DR = 8.39 kj/mol) indicates that the process is associated to chemical interactions (rather than pure physical sorption). In addition the values of thermodynamic parameters (Delta G degrees and Delta H degrees) show that the process is spontaneous and exothermic. The positive value of Delta S degrees means that the randomness of the system increased with sorption. Finally, the adsorbent can be efficiently regenerated and recycled for at least 5 cycles using acidified urea as the eluent. (C) 2014 Elsevier B.V. All rights reserved.