Synthesis of magnetic barium hydroxyapatite nanoparticles and their application for the removal of heavy metals from polluted waters

Pollution from heavy metals has increased in recent decades and has become an important concern for environmental agencies [1]. As these metals are non-biodegradable, they remain in the nature for a long time, and through deep percolation into underground water they can cause degradation of ecosystems [2]. So these toxic heavy metals should be removed from polluted water to protect people and the environment [3].Magnetic barium hydroxyapatite nanoparticles (MBaHANPs) were synthesized and used as an adsorbent for the removal of heavy metals from aqueous solutions. The synthesized adsorbent was characterized by XRD, SEM and FT-IR. A simple home-made device was used for continuous removal of metal ions and collection of the magnetic sorbent by a permanent magnet. The effect of different parameters on the removal efficiency of heavy metals such as pH of solutions, amount of adsorbent, stirring time and circulation time were optimized by a central composite design (response surface) method and effect of stirring rate and flow rate were studied by a one-at-a-time procedure. Under the optimized conditions, sorbent capacities of 66.5 mg.g-1, 91.2 mg.g-1, 99 mg.g-1 and 88.1 mg.g-1 were obtained for Cr3+, Cd2+, Pb2+ and Cu2+, respectively. The MBaHANPs adsorbent successfully removed the studied metal ions from polutted water samples and therefore may be used for water purification and removal of pollutants from industrial effluents.