Magnetic halloysite nanotubes/iron oxide composites for the adsorption of dyes

Iron oxide nanoparticles were synthesized on the halloysite nanotube (HNT) to prepare the magnetic sorbent HNT–Fe3O4, which was explored the adsorption for three dyes, namely methylene blue (MB), neutral red (NR) and methyl orange (MO). HNT–Fe3O4 was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. HNT was attached with clusters of Fe3O4 nanoparticles, and the HNT component was about 50.5 wt% in HNT–Fe3O4. Magnetic properties illustrated that HNT–Fe3O4 was superparamagnetic with a saturation magnetization (27.91 emu g−1). The magnetic HNT–Fe3O4 exhibited better adsorption on MB than NR, while the adsorption of MO was very little. And as the adsorbent, HNT–Fe3O4 could be easily separated from the aqueous solution in a magnetic field.