Manganese Dioxide And Iron Oxide Functionalized Acid Oxidized Multi-walled Carbon Nanotube For Cadmium And Chromium Ions Removal From Aqueous Solution

The physical and chemical properties of carbon nanotubes (CNTs) offer unprecedented opportunities for the novel applications of these materials in many fields expecially in adsorption. In this work, metallic oxide was coated onto oxidized multi-walled CNTs (o-MWCNTs) to improve dispersion, reusability and adsorption capacity, and use as adsorbent for heavy metal ions removal. The adsorption behavior of metallic oxide functionalized o-MWCNTs for the removal of heavy metal ions were investigated in detail. These results may provide ideas for other works.This study presents a simple route for the fabrication of manganese dioxide (MnO2) and iron oxide (Fe3O4) were coated onto o-MWCNTs. The materials were characterized by different techniques, such as Fourier-transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry and so on. Different materials were prepared as adsorbent for Cd2+and Cr6+to determine the adsorption capacities of adsorption materials. The MnO2/o-MWCNTs synthesized at pH=5.0were the most effective materials for removing heavy metal ions. The adsorption equilibrium time strongly depended on concentration and temperature. The initial solution pH has an apparent effect on the adsorption capacity of materials. The kinetic data of the adsorption under all investigated conditions fitted well with the pseudo-second-order kinetic model and Langmuir isotherm model. Moreover, the thermodynamic parameters indicated that the adsorption processes were spontaneous and endothermic. The overall rate processes were apparently influenced by external mass transfer and intraparticle diffusion. Heavy metal ions adsorptions onto the materials are complex processes, the mechanism of which may include both physical and chemical adsorptions.