Heavy Metal Ions Uptake by AlPO-5 and SAPO-5 Nanoparticles: An Experimental and Modeling Study.

Synthesis of AlPO-5 and SAPO-5 nanoparticles was followed by applying hydrothermal method to use them as adsorbents in the removal of Fe3+, Pb2+, and Cd2+ions.The synthesized products were characterized using powder X-ray diffraction, scanning electron microscope (SEM), FTIR and BET analysis. The adsorption isotherms and kinetics including Langmuir, Freundlich, pseudo-first order, pseudo-second order and intraparticle diffusion models have been employed. The experimental adsorption equilibrium and kinetic data nearly followed the Langmuir isotherm and pseudo-second order kinetic model, respectively. It was found that the existence of the bridging hydroxyl group in the SAPO-5 structure causes chemisorption of Fe3+, Pb2+, and Cd2+ions on SAPO-5 which have greatly improved the performance of this adsorbent against its low external surface area. Using AlPO-5 and SAPO-5 as novel adsorbents in heavy metal adsorption for the first time indicated the great potential of these adsorbents in removal of heavy metal ions from water.