Preparation Of Grapheme-based Composites And Its Photolysis Properties Of Tylosin

The antibiotic residues in environment increases gradually along with expensive using of antibotics in medical and animal husbandry, which will produce adverse effect to human life directly or indirectly. Photocatalytic degradation has received widespread attention because it is the main way to remove the antibiotics in environment. Graphene has been widely applied in catalysis because of the huge specific surface area and high electron mobility. Currently graphene is used to modify single-component semiconductor photocatalyst to improve the photocatalytic properties. A variety of graphene-based photocatalyst composites have been synthesized in this thesis, the as-prepared samples were characterized by means of SEM> TEM、TIR、XRD and other methods to observe the surface morphology, structure and so on. We have discussed the degradation property of graphene-based photocatalyst composites at the same time, the main contents are as follows:(1) The preparation method of graphene oxide (GO) is improved Hummers method. Using chemical oxidation to obtain GO with graphite powder as raw materials and thick H2SO4, H3PO4 and KM1O4 as oxidant. We can conclude that GO is composed of single or multilayer overlapping layers and fold structure appears on the surface with characterizing by means of SEM, XRD, FTIR and other methods. On the surface of GO, we found-COOH,-OH, C-OH, C= O, C-O-C oxygen-containing functional groups, which make GO have good hydrophilicity. GO can degrade tylosin under visible light irradiation, and we guess the main mechanism is appearing of free radicals.(2) Preparing goethite/graphene composites by hydrothermal and in situ growth method respectively. Characterized by SEM, XRD, FTIR and other methods, we can found that a fine acicular goethite uniform load at the surface of GO, which explains that the prepared composites of goethite/graphene is successful; at the same time, we can found that GO were reduced to grapheme. Through the experiments of photodegrade tylosin, we can know that photocatalytic properties of compound has obvious increased, and in situ growth method is superior to the hydrothermal method. Through the results of experiment we can know that the hydroxyl radicals (·OH) would oxidate tylosin to the final products.(3) Making preparation of Bi2WO6 by hydrothermal method, with Bi(NO3)3·5H2O and Na2WO4·2H2O as raw materials; making preparation of the Bi2WO6/GO composites by hydrothermal method too; making preparation of the Ag/Bi2WO6/GO composites by photo-reduction method. Characterized by means of SEM, XRD, FTIR and AFM, the results show that prepared composites of Bi2WO6, Bi2WO6/GO, Ag/Bi2WO6/GO is successful. Through the experiments of photodegrade tylosin, we can found that Bi2WO6/ GO and Ag/Bi2WO6/GO composites can improve the efficiency of degradation, and the photodegradation performance of Ag/Bi2WO6/GO is best. The photolysis mechanism of Bi2WO6 complexes on tylosin can be obtained, it is that GO and Ag would reduce the compound of electronic-hole, and silver played a significant role in the transfer of interface charge, at the same time, Super oxygen free radical (·O2) and hydroxyl free radicals (·OH) can decompose the tylosin to the final products.