Abstract:
In this work, an efficient adsorbent for the removal of chromium (IV) was prepared. The
examined heavy metal adsorbents are Fe3O4 and MnO2 nanoparticles, nanoclay, Fe3O4/Clay and
MnO2/Fe3O4/Clay nanocomposites. The MnO2/Fe3O4/Clay nanocomposite is used for the first
time for detection of heavy metal ions. The adsorption studies showed that nanoparticles have
very low removal efficiency whereas Fe3O4/clay composite showed better removal of toxic metal
ions. The maximum removal was observed for MnO2/Fe3O4/Clay nanocomposite. The maximum
adsorption capacity of MnO2/Fe3O4/Clay nanocomposite was calculated as 384 mg/g which is
the highest among all the used adsorbents. The reported adsorption capacity is higher than the
previously reposted adsorbent capacities for chromium. During the synthesis of
MNO2/Fe3O4/Clay nanocomposite, Fe3O4 and MnO2 nanoparticles are efficiently assembled over
the surface of nanoclay (Cloisite 30-B). MnO2/Fe3O4/Clay nanocomposite was found to be more
effective for the removal of chromium (cr6+) ions via adsorption process where the adsorption
was found to be strongly dependent on the initial pH of the solution. The maximum adsorption
capacity was calculated to be 384 mg/g. Contact time and kinetics of adsorption confirmed that
the process can be explained by pseudo second order rate equation. Obtained results demonstrate
that MnO2/Fe3O4/Clay nanocomposite could be exploited as a promising material for the
efficient removal of chromium from wastewater.
The morphology, chemical, optical and structural properties of nanoparticles, nanoclay and
nanocomposite were studied using Scanning electron microscopy (SEM), Fourier transform
infrared (FTIR) spectroscopy, ultra-violet visible (UV-Vis) spectroscopy and X-ray diffraction
(XRD). SEM showed that the prepared nanoparticles are uniformly dispersed over the clay
surface, without any agglomeration. FTIR analysis confirmed the various bonds within the clay
structure along with the metal oxide bonds of nanoparticles. The peak position and intensity
confirmed the physical assembling of nanoparticles on clay. XRD showed the corresponding
peaks of MnO2/Fe3O4/Clay nanocomposite.
