| Water is the source of life and our daily life, agricultural production and industrial synthesis can not live without water. With the rapid development of industrial economy, water environment problems have become increasingly prominent. At present, water pollution is becoming more and more complicated, various pollutants are mixed. Among them, the dye pollution accounts for a large part of them. Because of containing a large number of toxic organic residues, inorganic substances, acid, alkali, it will not only harm the environment and affect human health, but also affect the beauty of the water body. In addition, water bacterial pollution will affect human health, such as Shigella, Salmonella enteritidis, Escherichia coli, cholera vibrio and Campylobacter coli. Therefore, it is very necessary to find a kind of material which can remove the dye effectively and have the antibacterial function.In this paper, magnetic chitosan-graphene oxide composite(MCGO), a new multifunctional composite with antibacterial property and adsorption capacity, was synthesized followed by synthesis of graphene oxide(GO) by modified Hummer`s method, which combine the respective characteristics of chitosan and GO. And then study the antibacterial propert y of Escherichia coli and adsorption property of methyl orange dye. The specific research work and the results obtained in this paper include the following three parts:In the first part, MCGO was synthesized and characterized. Scanning electron microscope(SEM), transmission electron microscope(TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR) and Zeta potential determination were used to characterize the MCGO. Results showe d that iron oxide particles are concentrated and homogeneous distributed on the surface of graphene oxide. MCGO have the characteristic peak of Fe3O4, can be separated from solution when exposing to an external magnetic field, and contain a lot of oxygen functional groups. The isoelectric point was 10, when p H<10, t he adsorbent surface was positively charged, when p H>10, the adsorbent surface was negatively charged.In second part, the antibacterial performance for MCGO against Escherichia coli was studied. We investigated the antibacterial performance of iron oxide nanoparticles, GO, chitosan(CS) and MCGO, effect of MCGO concentration on the antibacterial activity of Escherichia coli, the changes of cell morphology before and after contact with Escherichia coli. Results showed that the antibacterial performance of four kinds of materials was in the order: MCGO > CS > GO > iron oxide nanoparticles. The antibacterial property of MCGO increased gradually with the increase of the material concentration. After 20 min of contact, the antibacterial rate increased from 53.85±15.39% to 99.91±0.02% with the material concentration increased from 50 μg/m L to 200 μg/m L. The addition of Mg2+, Ca2+ and Ba2+ will inhibit the antibacterial propety of MCGO. The damage of cell membrane was an important cause of death of Escherichia coli.In the third part, the adsorption capacity of MCGO for methyl orange was studied. The experimental parameters including adsorbent mass, p H value, contact time and concentration of methyl orange on the adsorption capacity were investigated. In addition, the regeneration of MCGO was investigated. Results showed that with adsorbent doss increased, the adsorption capacity of MCGO decreased, while the removal rate increased. The adsorption capacity of methyl orange decreased with the increase of initial p H value. Adsorption process followed the pseudo second order kinetic model and Langmuir isotherm very well. The maximum adsorption capacity of MCGO for methyl orange was 398.08mg/g. MCGO could be reused repeatedly. |
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