| With unique structure and excellent performance, the magnetic nanomaterials are widely used in magnetism, catalysis, information and biological medicine, becoming the hot spot in current research. As adsorbents, clay mineral materials such as kaolin and kaolinite nanotubes, the performance of which is restricted because of small powder particles and the difficulty to realize solid-liquid separation. Therefore, in this paper we take clay materials as the carrier and load the magnetic nanoparticles on their surface to prepare the magnetic kaolinite/kaolinite nanotubes that have both excellent magnetic performance and adsorption properties. Then discuss their application in dyes wastewater which contains MB. The main contents are as follows:Magnetic kaolinite composites powder were prepared through chemical coprecipitation method by taking raw kaolin as the carrier, Fe Cl3·6H2O, Fe SO4·7H2O and NH3·H2O as the starting materials. When the quality ratio of the Fe3O4: kaolin =1:5, there existed a single Fe3O4 phase with the grain size from10 to 30 nm and the grains were evenly loaded on the surface of kaolinite crystals. The composites had excellent magnetic property and the magnetic separation rate was 90.12%. The removal rate of kaolin and composites power for MB was gradually increased with the extension of adsorption time and the value of the adsorption equilibrium were 98.46% and 76.75% respectively. Besides, the removal rate of the composites to MB increased with the dosage of composites, the elevation of temperature and the increment of p H value, and decreased with the increasing of the initial concentration of MB. However, the adsorption capacity to MB increased with the increasing of initial concentration of MB.Kaolinite nanotubes(KNTs) were prepared via solvothermal method by taking kaolin as the raw material, DMSO, CH3 OH and CTAC as the intercalating agents. KNTs had perfect morphology, smooth surface area and the outer diameter about 50-60 nm, the inner diameter about 25-30 nm, the length of 300-1000 nm, the specific surface of 45.44 m2/g. The removal rate of KNTs to MB increased with the increment of p H value and the dosage of KNTs. The adsorption capacity to MB increased with the extension of adsorption time, the increasing of initial concentration of MB and the elevation of temperature, and decreased with the increasing of the dosage of KNTs. When the dosage was 0.06 g, the removal rate were 95.68% and the adsorption process was conformed to the pseudo-second-order model.The isothermal adsorption data fitted the Langmuir and Freundlich isotherm model well. The maximum adsorption capacities of KNTs were 30.30 mg·g-1 at 298 K.We obtained the magnetic kaolinite nanotubes(MKNTs) by coprecipitation method. After loaded with magnetic nanoparticles, the morphology of KNTs was complete and uniform.The particles were coated on the surface of KNTs mainly in the form of Fe3O4 and γ-Fe2O3. MKNTs exhibited rapid adsorption rate and could reach adsorption equilibrium at 20 min. The removal rate of MKNTs to MB increased with the increment of p H value and the dosage of MKNTs. The adsorption capacity to MB increased with the increasing of initial concentration of MB and the elevation of temperature, and decreased with the increasing of the dosage of MKNTs. The adsorption followed pseudo-second-order model well, and the isothermal adsorption complied with the Langmuir and Freundlich isotherm model. The maximum adsorption capacities of MKNTs were 24.18 mg·g-1 at 298 K, comparing with KNTs, there was no significant lower. Taking contrast with raw kaolin materials, magnetic kaolinite, KNTs and MKNTs, we knew that MKNTs had rapid adsorption rate, good magnetic performance and high efficiency adsorption properties.For calcination, MKNTs can realize regeneration. And after recycling adsorption/desorption 7 times, MKNTs still had better magnetic performance and adsorption properties, the removal rate of MKNTs for MB was 58.56%. |
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