| In daily life, colorful dyes can be found everywhere especially in textile and food processing industry. However dye wastewater is one of the most difficult to deal with industrial wastewater which has high chromaticity, complicated components, and high organic matter content, great toxicity. Its existence not only polluted the environment, but also produced a serious harm to our health. Therefore to research a simple and efficient wastewater treatment method is imminent.At present, the azo dyes wastewater treatment methods mainly consist of physical method, chemical method, biological method and some combination technology.In these methods, physical adsorption technology is widely used because of the simple operation, low energy consumption and high efficiency. Usually People select activated carbon and chitosan as the main adsorbent, but the high cost and easy hydrolysis limit their application, so to develop the new adsorbent which is high efficiency, low price, easy to regenerate is particularly important. One-dimensional hollow nanomaterials have caused extensive concern due to their empty nanostructure and large specific surface area. But the characteristics of nanometer structure makes it easy to drift, difficult to settlement and recycling. In this regard, numerous studies were launched, finally the magnetic separation technology provides a good solution to this problem.Halloysite and carbon nanotubes were selected as the research objects in this paper, and magnetic halloysite(MHNTs) and magnetic carbon nanotubes(MCNTs) were prepared by sol-gel method, studying on the adsorption properties of this two kinds of adsorbents for Rhodamine B, the work and conclusions are included as follows:(1)MnFe2O4/HNTs and MnFe2O4/CNTswere prepared by sol-gel method, the samples were characterized by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),Furrier transform infrared(FT-IR) and vibrating sample magnetometer(VSM). The results indicated that HNTs and CNTs have been successfully load on MnFe2O4 magnetic particles,the composites exhibited strongly magnetic property and the saturation magnetization of MHNTs was 26.22emu/g. Compared with MHNTs, the magnetic ions on the MCNTs surface is not uniform, magnetic energy is weaker, but can still played well the role of magnetic separation.(2) The adsorption performances of magnetic nanocomposites to Rhodamine-B were investigated by batch mode experiments with respect to quantity of adsorbent, pH, concentration and temperature. Results of a study showed that the removal rate was close to 100% when dosing quantity was 0.05 g for MHNTs. The initial pH was chosen finally because pH has little influence on adsorption performance. The adsorption quantity would increase with the growth of initial concentration and temperature. But for MCNTs, the removal rate was close to 100% when dosing quantity was 0.025 g,unlike MHNTs, the adsorption quantity would decrease with the growth oftemperature.(3) All of the equilibrium data of MHNTs fit well with the Langmuir isotherm model, the adsorption quantity would be increased with the higher temperature, this phenomenon showed that the adsorption process was endothermic reaction. The kinetic data were more fitted to the pseudo-second-order equation. But the results show that the Freundlich model is more closed to the adsorption process of MCNTs,, the adsorption process was exothermic reaction. The kinetic data were good fitted to the pseudo-second-order equation as well. Finally, the regeneration performance of the MCNTs and MHNTs were studied through calcination and solvent method, the results show that the regenerability of the composites were very well after several cycles, the adsorption performances of MCNTs is better than MHNTs, the regeneration rate still reached more than 90%. |
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