Preparation Of Fe₃O₄-based Magnetic Nanocomposite Materials And Their Adsorption Properties For Dyes

With the rapid development of printing and dyeing industry in China, more and more printing and dyeing wastewater is being discharged into environmental water.So it has great theoretical and realistic significance to study and develop highly effective treatment methods and techniques for dye wastewater. Among the wastewater treatment methods, adsorption method has been applied widely for its simple operation, fast speed and high efficiency. Especially magnetic adsorbent can reduce remarkably the energy consumption of the separation process due to easy separation and simple operation. In this thesis, three kinds of Fe₃O₄ based magnetic nanoscale composite sorbents some with high adsorption performance for different types of dyes were designed and prepared, and their structures and properties were characterized detailedly. The thesis consists of four chapters as follows:Chapter one The progress on study and application of the adsorption method in wastewater treatment was summarized. Especially, the preparation and application of magnetic nanosorbents were discussed in detail.Chapter two Using glutaraldehyde as crosslinking agent, chitosan was grafted onto Fe₃O₄ nanoparticles coated by SiO₂ to obtain magnetic chitosan nanocomposites?CMS?. At last ethylenediamine modified magnetic chitosan composite nanosorbent?EDCMS? was successfully synthesized and its adsorption property to acid fuchsine solution was studied. The results showed that the decolorization rate of the prepared sorbent was above 98.04% and the maximum adsorption amount reached 284 mg.g^-1under optimal conditions. The adsorption process obeyed the quasi-second adsorption rate equation and Freundlich isothermal adsorption model.Chapter three With a chemical coprecipitation procedure magnetic oxide graphene?MGO? was prepared through Fe₃O₄ nanoparticles coating graphene oxide?GO? obtained by Hummers method. The results showed that the prepared adsorbent had a high removal efficiency for methylene blue. The decolorization rate was more than 96.48% and the maximum adsorption quantity reached 77.57 mg.g^-1.The adsorption process conformed to the quasi-second rate equation and the Langmuir adsorption isothermal adsorption model.Chapter Four Magnetic activated carbon composite material?MC? with magnetic separation performance and strong adsorption performance for methyl orange wassynthesized with a simple chemical coprecipitation method. The results indicated that the decolorization rate of the magnetic adsorbent for methyl orange was above 80.2%,and the maximum adsorption amount reached 95.92 mg.g^-1. The quasi-second adsorption rate equation and the Langmuir isothermal adsorption could describe the adsorption process.