Alumina nanoparticles immobilization onto the NaX zeolite and the removal of Cr (III) and Co (II) ions from aqueous solutions

• Facilitate the use and reuse of alumina nanoparticles as an adsorbent, by immobilization.
• Improving the NaX zeolite performance by immobilization of alumina nanoparticles on it.
• Maximizing the removal of Cr (III) and Co (II) ions from aqueous solution by optimizing the experimental conditions.
• Kinetics and equilibrium studies for the removal of Cr (III) and Co (II) ions.

The immobilization of alumina nanoparticles onto the NaX zeolite granules, using the sol–gel and a physical method, for the removal of Cr (III) and Co (II) was investigated. Alumina nanoparticles immobilized zeolite (ANIZ) was characterized by SEM/EDX, XRD and AAS. The results suggested the formation of nanoscale alumina (∼30–50 nm) on the zeolite (loading ∼8–10 wt%) and the stability of the zeolite structure after the immobilization of alumina nanoparticles. ANIZ showed a good capacity for the removal of metal ions. Kinetic and equilibrium data were best fitted with the pseudo second order model and the Langmuir model respectively.