Novel magnetic NiFe2O4/multi-walled carbon nanotubes hybrids: Facile synthesis, characterization, and application to the treatment of dyeing wastewater

Novel magnetically recyclable spinel nickel ferrite/multi-walled carbon nanotubes hybrids (NiFe2O4/MWCNTs hybrids) with different MWCNTs content were prepared by a facile one-step hydrothermal method. The as-prepared NiFe2O4/MWCNTs hybrids were characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Photocatalytic activity of NiFe2O4/MWCNTs hybrids was investigated by photocatalytic decolorization of Congo Red (CR) in aqueous solution under simulated solar light irradiation. NiFe2O4/MWCNTs yielded efficient decolorization of CR solution with an apparent rate constant of 0.01433 min−1, which was 2.18 times that of NiFe2O4. Significantly enhanced activity of NiFe2O4/MWCNTs hybrids resulted from the synergistic contribution of both high adsorption capacity towards CR and the participation of holes (h+),
• OH radicals and O2
• − radicals. In addition, the NiFe2O4/MWCNTs hybrids can be recovered conveniently using an external magnet. As a result, the novel NiFe2O4/MWCNTs could gain a promising application in treatment of various dyestuff wastewaters on a large scale.