| Water pollution has become a serious global environmental problem in recent years, causing serious harm to the environment and human health. The pollutant was removed effectively is an important way to control water pollution. Magnetic nanoadsorbent is a novel adsorbent material, which has a wide application prospect in the field of separation due to large specific surface area and easy separation; it developed a new vision for removing and rapid separation of pollutants in water. However, the basic premise of achieving rapid separation and remove of water contaminants is the preparation of environment friendly magnetic adsorbent which has better adsorption properties. Therefore, environmental chelating agent N,N-bis (carboxymethyl) glutamicacid (GLDA)-modified chitosan/Fe304 magnetic nanoadsorbent was prepared which possessed good biocompatibility and its adsorption properties were investigated to Cd (?) ions (inorganic metal ions) and methylene blue (organic dye) from aqueous solution. The main results were as follows:(1) A novel environment friendly magnetic nano-adsorbent (GLDA-MCTS) was prepared by the covalent binding of GLDA onto the surface of chitosan-coated Fe3O4 nanoparticles prepared by co-precipitation method (MCTS), which was characterized by scanning electron microscopy (SEM), infrared spectrum (IR), vibrating sample magnetometer (VSM) and X-ray powder diffractometer (XRD). It was found that Fe3O4 was modified successfully by chitosan and GLDA, GLDA-MCTS has a spherical structure with a particle size ranged from 100nm-150 nm, saturation magnetization value of 21emu/g and the crystal structure of Fe3O4 was not destroyed during the whole preparation processes.(2) The adsorption performances of GLDA-MCTS are tested with adsorption of Cd (?) ions from aqueous solution. Correspondingly, the adsorption effect factors (initial concentration, solution pH, contact time and temperature), adsorption kinetics, isotherms, adsorption thermodynamic and regeneration were investigated in detail. The results show that adsorption capacity of GLDA-MCTS for Cd (?) ions is relatively stable when the pH value is 4.0-6.0. In additional, the adsorption models indicated that the adsorption is dominated by chemical adsorption and the adsorption process was spontaneous exothermic. What's more, GLDA-MCTS showed a high maximum adsorption capacity of 625 mg/g for Cd (?) ions than other chitosan based adsorbents because of size-minimization. After being desorbed by EDTA, GLDA-MCTS can be used again.(3) The adsorption performances of GLDA-MCTS are tested with adsorption of methylene blue from aqueous solution. Correspondingly, the adsorption effect factors (initial concentration, solution pH, contact time, temperature and ionic strength), adsorption kinetics, isotherms, adsorption thermodynamic and regeneration were investigated in detail. The results show that the optimal pH for adsorption of methylene blue was 11.0 in the experimental range. In additional, the adsorption models indicated that the adsorption is dominated by chemical adsorption and the adsorption process was spontaneous endothermic. What's more, GLDA-MCTS showed a high maximum adsorption capacity of 3.3g/g for methylene blue than other chitosan based adsorbents because of size-minimization. Besides, the adsorption capacity was more than 90% of the initial saturation adsorption capacity after being used for four times by ethanol.In summary, an environment friendly and renewrable magnetic nanoadsorbent was prepared and the adsorbent has better adsorption properties for Cd (?) ions and methylene blue from aqueous solution. The attempt work not only provide a basic material for the rapid removal of Cd (?) ions and methylene blue, but also ideas for preparation of magnetic adsorbent to inorganic ions and organic contamination dye in water. |
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