Double Functional Group In Preparation Of Magnetic Chitosan Nanoparticles Microspheres And Sewage Treatment

Chitosan is a natural polymer compound, which possess non-toxicity, hydrophilicity, biocompatibility, biodegradation properties and so on. Chitosan can absorb or chelate heavy metal ions, some protein and starch, because its molecular surface contains a lot of free amino and hydroxyl. In recent years, chitosan as a cheap effective adsorbent has received great attention. However, the application of chiotsan as sorbent has been limited, since the molicular contains a large number of amino which can easily be protonated by combining H+in water and dissolve in acid sollution.The chitosans modified with thiourea, carboxyl and EDTA were prepared in this paper, which improved the adsorption capability and stability of chitosans sorbent and broaden the the scope of their application. Nanometer Fe3O4particles were coated by crosslinked chitosan. A rapid separation of the adsorbent from wastewater solutions was achieved by magnetic separation technology. Furthermore, Pb2+imprinted magnetic chitosan nano-materials were also prepared in order to improve the selectivity of the adsorbent for the template ion. The specific research contents and the results are as follows:1. Preparation and characterization of Fe3O4nanoparticlesMagnetic Fe3O4nanoparticles were prepared by chemical co-precipitation method. Morphology and size of the Fe3O4particles were observed by Field-emission scanning electron microscopy (FE-SEM). It was observed that the microstructure of Fe3O4is spherical and the average size of Fe3O4powders is about20-30nm. Crystal phase identification was carried out on an X-ray diffractometer (XRD) using40kV,20mA, and Cu Kα radiation (1.5406A). The results show that the prepared Fe3O4is a single pure phase and belongs to the inverse spinel crystal structure.2. Modified magnetic chitosan, the synthesis and characterization of nanomaterialsCarboxyl-modified Magnetic crosslinking chitosan was prepared used a-ketoglutarate by inverse-phase suspend polymerization method. Amino-modified magnetic chitosan was also prepared used glutaraldehyde and ethylenediamine. Morphology and size of the microspheres were observed by SEM. Structures and compositions of the prepared adsorbents were characterized by fourier transfer infrared (FT-IR) spectrameter、XRD、differential scanning calorimetry (DSC) and thermogravinetry (TG). The results show that the prepared adsorbents are sphericity with uniform size and the average size is about80-90nm. Carboxyl and amino-modified chitosan were prepared successfully.3. Modification of magnetic chitosan microspheres adsorption performance researchThrough reaction with thiourea, carboxyl and EDTA modified magnetic chitosan nano materials was obtained. Effects of environmental factors on their adsorption properties were also studied. The results reveal that both of the two adsorbens are in a relatively short period of time to reach saturation adsorption and EDTA modified chitosan magnetic nano materials show a greater adsorption capacity.4. Studies on preparation and adsorption behavior of Pb2+-imprinted magnetic cross-linked chitosan nano-materialsPb2+-imprinted magnetic cross-linked chitosan nano-materials were prepared and their Adsorption capability was also investigated. The results show that the imprinting adsorbents show several advantages, such as high selectivity for the adsorption of Pb2+, simple regeneration conditions, good stability (insoluble in acid solution) and high recycling rate.