Preparation of Magnetic Kaolinite Nanotubes for the Removal of Methylene Blue from Aqueous Solution

Kaolinite nanotubes (KNTs) were prepared by using a solvothermal method and natural kaolin as raw material. Magnetic kaolinite nanotubes (MKNTs), whose mass ratio of Fe3O4 to KNTs is 1:5, were prepared by the chemical co-precipitation method. The methylene blue (MB) adsorbing ability of the as received materials was studied. The chemical and mineral composition, structure and morphology of samples were investigated using X-ray fluorescence spectrometry analysis, X-ray powder diffraction, field-emission scanning electron microscopy, infrared spectroscopic analysis and N-2 adsorption-desorption isotherm. A set of experiments were carried out under different conditions of contact time, adsorbent dosage, temperature, initial MB concentration and pH value to investigate the adsorption behavior of MB onto MKNTs. 94.20% of MB was removed by adding 0.04 g MKNTs into a 10 mg L-1 solution (50 mL) at 298 K for 20 min. The experimental adsorption data followed a pseudo-second-order kinetic model and Langmuir isotherm. MKNTs showed excellent magnetic separation property and reusability.