| The environment is polluted by industrial wastewater more and more seriously with the development of industry. Wastewater containing dyes discharged destroys environmental balance and human health seriously due to high chromaticity and toxicity. Pre-treatment of wastewater containing dyes before discharging is the most radical method, physical-chemical method, chemical method and biological method are normal methods for dye removal, among these methods adsorption is one of the most popular and effective process, to develop an adsorbent with high adsorption ability has attracted much interest of scientists in recent years.Chitosan is a kind of natural polymer. It is an ideal adsorbent due to a large number of amino and hydroxyl groups in the molecule structure which can interact with some functional groups. Chitosan coated magnetic particles which can be used by magnetic separation in the adsorption process has been the hotspots of research.Due to high specific surface area, high cation exchange capacity and adsorption ability, bentonite is an ideal adsorbent which can be used for the treatment of waster containing dyes. In common, bentonite should be modified to improve its adsorption ability. After being modified by polymer, the adsorption ability of bentonite can be largely improved due to the numerous adsorption sites on the repeated units of polymer chains. The atom transfer radical polymerization(ATRP) is a polymerization method with many excellent advantages, such as well-defined structure, controlled molecular weight distribution, the polymerization process is also easily controlled, it provides a highly efficient and convinent method for preparation of polymer modified bentonite.In this thesis, the main research are as follows:1. Magnetic adsorbent Fe3O4@CS was prepared by a one-step method. Then the stuctures and properties of the magnetic adsorbent were characterized by FT-IR, XRD, TGA and TEM. The results stated that Fe3O4@CS has a core-shell structure that chitosan uniformly coated on Fe3O4. The effects of solution pH, initial concentration and contact time to find the optimal adsorption condition and the maximum adsorption amount of Fe3O4@CS was 183.2 mg·g-12. Bent-PGMA-TEPA, Bent-PDMAEMA and Bent-PSPMK were prepared by the atom transfer radical polymerization using glycidyl methacrylate(GMA), 2-(dimethylamino)ethyl methacrylate(DMAEMA) and 3-Sulfopropyl methacrylate potassium salt(SPMK) as monomers respectively. Then the stuctures and properties of the obtained adsorbents were characterized by FT-IR, XRD, TGA, SEM. The results stated that polymer brushes were successfully grafted on the surface of bentonite.3. Bent-PGMA-TEPA and Bent-PDMAEMA were used in the adsorption of an ionic dye, orange I. Bent-PSPMK was used in the adsorption of a caionic dye, Rhodamine B. The effects of solution pH, initial concentration, temperature and contact time were investigated respectively to find the optimal condition and maximum adsorption amount of the adsorption process. In addition, the adsorption mechanism, equilibrium adsorption isotherm and adsorption kinetics were also discussed. The results stated that the maximum adsorption amounts of Bent-PGMA-TEPA and Bent-PDMAEMA were 616.6 and 710.7 mg·g-1 respectively for the adsorption of orange Ⅰ and the maximum adsorption amount of Bent-PSPMK was 2261 mg·g-1 for the adsorption of Rhodamine B. Compared with other adsorbents, the adsorbents prepared in this research has better adsorption capacity.4. Compared with other adsorbents, polymer modified bentonite adsorbents had better adsorption ability and higher value in practical use. |
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