Manganese oxide, Iron oxide Magnetic Clay Composite for the Detection of Chromium from Solution

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.