Highly efficient adsorptive removal of uranyl ions from aqueous solutions using dicalcium phosphate nanoparticles as a superabsorbent

Dicalcium phosphate nanoparticles (DCP-NPs) was synthesized chemically and used for adsorptive removal of uranyl ions from aqueous solutions in a batch system. A commercial grade of DCP (monetite) was also employed for comparison. The synthesized and commercial adsorbents (S-DCP and C-DCP) were characterized by FT-IR, SEM and XRD techniques. The investigation of adsorption isotherms indicated that the maximum adsorption capacities (qm) for C-DCP and S-DCP were 714.3 and 666.7 mg g−1 (at 293 K), respectively. The experimental kinetics were well-described by the pseudo-second-order kinetic and the equilibrium data were fitted with both Langmuir and Freundlich adsorption models. Thermodynamic studies indicated that the adsorption of uranyl ions on the monetite surface was a spontaneous exothermic process. The exhausted adsorbents could be regenerated by washing with 0.10 mol L−1 NaOH. Keywords: Uranium (VI), Monetite, Nanoparticles, Adsorption, Adsorption isotherm