| Dye wastewater with characteristics of a complex composition, high chroma and large emissions, toxic and difficult biodegradable, has been the problems in wastewater treatment. Conventional biological treatment, coagulation and sedimentation, adsorption, membrane separation technology for the poor mineralization of dye pollutants, and easily cause secondary pollution. So, the development of new processing technology, has become the focus of attention.In recent years, photocatalytic technology as an advanced oxidation technology is rising rapidly, and research will be more in terms of dye wastewater degradation. Among the bismuth-based composite oxide, bismuth tungsten has a high visible light activity. However, most of the process conditions for preparing bismuth tungstate demanding and costly. The thesis of this paper presents a new method for preparing.The method is based on nanofibers or wet spun fibers as the reactor to obtain Bi2WO6nanocomposite fibers with efficient visible light photocatalytic degradation performance by step preparation. The preparation method has a low reaction conditions, and low cost. The main contents are as follows:(1) Study on wet spinning preparation of bismuth tungsten/acrylic composite fiber, pre-oxidation and visible light catalytic performance.Bismuth nitrate, sodium tungstate and acrylic as raw materials, dimethyl sulfoxide as the solvent; the spinning solution have prepared by ultrasonic vibration and magnetic stirring; bismuth tungsten/pre-oxidation acrylic composite fiber catalyst have prepared by wet spinning; Investigate the photocatalytic activity and repeated performance of bismuth tungsten/pre-oxidation acrylic composite fiber catalyst under different temperatures and different temperature gradients, and characterization the catalyst having catalytic activity for the best. The results showed that the optimal conditions for wet spinning preparing bismuth tungsten/pre-oxidation acrylic composite fiber are: start from40℃, heating rate from10min/10℃to150℃, and heat preservation12h. This method have the advantages of preparation method is simple, requires low reaction conditions, and has easy separation, easy recovery. The degradation rate of methylene blue can up to84.81%by7h. But, bismuth tungstate on the fiber is not good adsorption fixed, easy to fall off, which resulting in poor performance of repeated use.(2) Study on electrospinning preparation of bismuth tungsten/acrylic composite nanofiber, pre-oxidation and visible light catalytic performance.Bismuth nitrate, sodium tungstate and acrylic as raw materials, N,N-dimethylformamide as the solvent; the spinning solution have prepared by ultrasonic vibration and magnetic stirring; bismuth tungsten/pre-oxidation acrylic composite nanofiber catalyst have prepared by electrospinning. Investigate morphology and diameter changes of bismuth tungsten/pre-oxidation acrylic composite nanofiber catalyst precursor under different electrospinning conditions. Investigate the photocatalytic activity and repeated performance of bismuth tungsten/pre-oxidation acrylic composite fiber catalyst under different temperatures, different temperature gradients and different holding time, and characterization the catalyst having catalytic activity for the best. The results showed that the optimal conditions for electrospinning preparing bismuth tungsten/pre-oxidation acrylic composite nanofiber precursor are:voltage22kV, the receiving distance15cm, flow rate of the spinning0.2mL/h, the morphology of the fibers preferably and have an average diameter of93nm. Optimal conditions for the preparation of bismuth tungsten/acrylic composite nanofiber photocatalysts is:start from40℃, heating rate from10min/10℃to220℃, and heat preservation12h. The degradation rate of methylene blue can up to95.53%by4.5h, and repeat8times using methylene blue degradation rate can reach83.88%by4.5h. It’s shows that bismuth tungsten/pre-oxidation acrylic composite nanofiber prepared by electrospinning with excellent photocatalytic activities and reusability.(3) Study on electrospinning preparation of bismuth tungsten/titanium dioxide/acrylic composite nanofiber, pre-oxidation and visible light catalytic performance.Bismuth nitrate, sodium tungstate, tetrabutyl titanate and acrylic as raw materials, N,N-dimethylformamide as the solvent; the spinning solution have prepared by ultrasonic vibration and magnetic stirring; bismuth tungsten/titanium dioxide/pre-oxidation acrylic composite nanofiber catalyst have prepared by electrospinning. Investigate the photocatalytic activity and repeated performance of bismuth tungsten/titanium dioxide/pre-oxidation acrylic composite fiber catalyst under different temperatures, different temperature gradients and different holding time, and characterization the catalyst having catalytic activity for the best. The results showed that the optimal conditions for the preparation of bismuth tungsten/titanium dioxide/pre-oxidation acrylic composite nanofiber photocatalysts is:start from40℃, heating rate from10min/10℃to240℃, and heat preservation12h. The degradation rate of methylene blue can up to95.34%by4.5h, and repeat6times using methylene blue degradation rate can reach81.43%by4.5h. It’s shows that bismuth tungsten/titanium dioxide/pre-oxidation acrylic composite nanofiber prepared by electrospinning with excellent photocatalytic activities and reusability.(4) Study on electrospinning preparation of bismuth tungsten/acrylonitrile-Acrylic copolymer composite nanofiber, pre-oxidation and visible light catalytic performance.Bismuth nitrate, sodium tungstate and acrylonitrile-Acrylic copolymer as raw materials, N,N-dimethylformamide as the solvent; the spinning solution have prepared by ultrasonic vibration and magnetic stirring; bismuth tungsten/pre-oxidation acrylonitrile-Acrylic copolymer composite nanofiber catalyst have prepared by electrospinning. Investigate the photocatalytic activity and repeated performance of bismuth tungsten/pre-oxidation acrylonitrile-Acrylic copolymer composite fiber catalyst under different temperatures, different temperature gradients and different holding time, and characterization the catalyst having catalytic activity for the best. The results showed that the optimal conditions for the preparation of bismuth tungsten/pre-oxidation acrylonitrile-Acrylic copolymer composite nanofiber photocatalysts is:start from40℃, heating rate from10min/10℃to200℃, and heat preservation12h. The degradation rate of methylene blue can up to90.24%by4.5h, and repeat5times using methylene blue degradation rate can reach81.53%by4.5h. It’s shows that bismuth tungsten/pre-oxidation acrylonitrile-Acrylic copolymer composite nanofiber prepared by electrospinning with excellent photocatalytic activities. |
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