Study of the Adsorption and Desorption of Zn(II) and Pb(II) on CaF2 Nanoparticles

This paper explores the adsorptive properties of CaF2 nanoparticles for the removal of Pb(II) and Zn(II) from aqueous solutions and their selective recovery. CaF2 nanoparticles were synthesized by a facile one-step reaction and characterized by N2 physisorption at 77 K, XRD, and TEM. The adsorption of Zn(II) and Pb(II) fits well with Elovich and Langmuir isotherm models, respectively. Kinetic data are well described by the pseudo-second-order model. Our results show that Zn(II) and Pb(II) could be totally and selectively desorbed with HCl solution (0.01 M). The results of the competitive adsorption and desorption of Pb(II) and Zn(II) show that Zn(II) is desorbed before Pb(II) leading to a good separation. The desorption yield reaches 89% for Zn(II) and 95% for Pb(II), which opens the route to regenerate the adsorbent for other cycles.