Characterization of magnetic guar gum-grafted carbon nanotubes and the adsorption of the dyes

The hydrophobicity of carbon nanotubes (CNTs) limits their extensive application. The hydrophilicity and biocompatibility of CNTs can be improved by modifying them with biopolymers. As a natural biopolymer, guar gum (GG) was covalently grafted on the surfaces of multiwall carbon nanotube (MWCNT) to obtain GG–MWCNT composite. Then iron oxide nanoparticles were synthesized on the GG–MWCNT to prepare the magnetic GG–MWCNT–Fe3O4. The obtained nanocomposites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, ultraviolet–visible (UV–vis) spectroscopy and X-ray diffraction. GG–MWCNT was composed of about 21.6 wt% GG components, which enhanced the dispersion of GG–MWCNT in aqueous solution and also acted as a template for growth of iron oxide nanoparticles. GG–MWCNT–Fe3O4 exhibited superparamagnetic with a saturation magnetization (13.3 emu g−1), and good adsorption on neutral red and methylene blue. GG–MWCNT–Fe3O4 could be easily separated from the aqueous solution in a magnetic field.