Heavy metal removal by using ZnO/organic and ZnO/inorganic nanocomposite heterostructures

Two types of ZnO/organic and ZnO/inorganic nanocomposite heterostructures, which were ZnO/polyaniline (PAni) and ZnO/graphene oxide, were used to remove heavy metal ion species, such as Cr6+, Cr3+, Cu2+ and Fe3+ in ambient conditions. These nanocomposites were tested as adsorbents. ZnO nanoparticles were synthesised by using a wet chemical precipitation method and then they were characterised by different characterisation techniques such as X-ray diffraction patterns, field emission scanning electron microscope and energy-dispersive X-ray. The synthesised composites revealed a good efficiency for removing the metal ion in complex water mixtures. Illumination of visible light source to a mixture containing chromate ion and adsorbents resulted in good degradation efficiency for chromate ion. Effect of pH on the removal of the metal ions was also studied. The adsorbents were able to adsorb the metal ions in the pH ranges from 6.5 to 9.0.