Chromium removal by combining the magnetic properties of iron oxide with adsorption properties of carbon nanotubes

The adsorption features of multiwall carbon nanotubes (MWCNTs) with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. Composites of MWCNT/nano-iron oxide were prepared, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD suggests that the magnetic phase formed is maghemite and/or magnetite. FESEM image shows nano-iron oxides attached to a network of MWCNTs. The adsorption capability of the composites was tested in batch and fixed bed modes. The composites have demonstrated a superior adsorption capability to that of activated carbon. The results also show that the adsorptions of Cr(III) on the composites is strongly dependent on contact time, agitation speed and pH, in the batch mode; and on flow rate and the bed thickness in the fixed bed mode. Along with the high surface area of the MWCNTs, the advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

The effect of pH on the amount of Cr(III) adsorbed.Figure optionsDownload high-quality image (50 K)Download as PowerPoint slideResearch highlights
► The MWCNT/nano-iron oxide magnetic composites were prepared and characterized.
► The composites show good adsorption capacity for chromium ions.
► The material could be used as a base for encapsulation in reverse osmoses systems.