Preparation Of Ag And Co²⁺ Doped Zno Hollow Fibers And Their Photocatalytic Property

In this thesis, ZnO, Ag and Co2+doped ZnO hollow fiber photocatalyticmaterials were successfully prepared by using cotton fiber as the template. Thecrystalline structure, morphology, light absorption property, surface structure and soon of photocatalytic materials were characterized by various techniques. Theirphotocatalytic properties were evaluated by using the degradation of dye methyleneblue （MB） solution as model reaction. This thesis mainly consists of following threemajor aspects.1. ZnO hollow fiber materials were prepared by using cotton fibers as thetemplate. The crystalline structure, morphology, light absorption property, surfacestructure and so on were characterized by the thermogravimetric analysis （TG）, X-raydiffractometry （XRD）, scanning electron microscopy （SEM）, UV-visible spectroscopy（UV-vis）, infrared spectroscopy （IR） and Zeta potential techniques. The effect ofcalcining temperature, calcining time, concentration and pH value of Zn（NO3）2solution, and pH value of MB solution on the photocatalytic property of ZnO hollowfibers was investigated by using the degradation of methylene blue （MB） solution asthe model reaction,. The results show that, in the alkaline condition of MB solution,the catalytic activity is best when ZnO hollow fibers were prepared by640oCcalcined3h with0.054mol·L-1and pH6.76of Zn（NO3）2solution. In addition, thelight source and light intensity also influence catalytic activity of ZnO. Illuminating30min under the300W mercury lamp, ZnO can make degradation rate of MBsolution above98%, and still keep above95%while they are reused4times. Thematerials are easy to separate and reuse.2. Cotton fibers would be soaked in Zn（NO3）2and AgNO3solution, then air driedand calcined to get Ag/ZnO hollow fiber materials. The crystalline structure,morphology, surface structure, light absorption property and so on were characterizedby the X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, X-rayphoto electronic spectrum （XPS）, infrared spectroscopy （IR） and UV-visiblespectroscopy （UV-vis） techniques. The effect of calcining temperature and Ag doped amounts on the photocatalytic property of Ag/ZnO hollow fibers was investigated byusing the degradation of methylene blue （MB） solution as the model reaction. Theresults show that, Ag/ZnO hollow fibers prepared by640oC calcined3h with1.1mol.%Ag doped amounts, respectively make degradation rate of MB solution97.4%and92.9%under500W xenon lamp and sunlight, illuminating2.5h. ZnO andAg/ZnO hollow fibers are reused5times and the catalytic activity of Ag/ZnO ishigher than that of ZnO, and degradation rate of MB is above86%. The materials areno energy consumption, no pollution, good property and green environment-friendlyphotocatalytic materials.3. Co²⁺ doped ZnO hollow fiber materials were prepared by using cotton fibersas the template to improve the optical absorption scope, enhance the utilization ratioof sunlight, or restrain the photoinduced electron-hole recombination, and increasingthe catalytic activity. The crystalline structure, morphology, light absorption propertyand so on were characterized by the X-ray diffractometry （XRD）, scanning electronmicroscopy （SEM） and UV-visible spectroscopy （UV-vis） techniques. The effect ofCo²⁺ doped amounts, n（Zn2+）:n（CA） and cobalt salts on the catalytic property ofCo²⁺/ZnO hollow fibers was investigated by using the degradation of methylene blue（MB） solution as the model reaction. The results show that, doped Co²⁺ could makeabsorption spectrum scope of ZnO further expand long wavelength direction andimprove the utilization rate of sunlight. Co²⁺/ZnO hollow fibers prepared by640oCcalcined3h with0.05mol.%Co²⁺ doped amounts and1:3of n（Zn2+）:n（CA）, havegood photocatalytic degradation efficiency of MB and can make degradation rate ofdye MB99.1%under the sunlight, illuminating2h. They can be repeated use.