Synthesis Of Polyester Fiber-Based Bi₂WO₆/BiVO₄/MWCNTs Composite Adn Its Photo-Catalytical Performance

The problems of high cost and secondary pollution in effluent treatment of dyeing operations have always been a study hotspot.In recent years,semiconductor photo-catalytic technology,which is a promising wastewater treatment,with low cost and non-pollution properties,has attracted researchers' sattention.In this paper,the photocatalytic composite material with good photocatalytic performance and excellent recycling performance is synthesized by loading Bi₂WO₆/BiVO₄/MWCNTs nano-composite?which is prepared through hydro-thermal method?onto the polyester fabric.The method of synthesizing polyester fiber-based nanocomposite photo-catalyst provides a potential applicationfor degrading organic pollutants in wastewater treatment.Firstly,the synthesis of Bi₂WO₆/BiVO₄/MWCNTs nanocomposite photo-catalyst was established via a two-step hydro-thermal method.Through the degradation of reactive dyes RB-19 under the visible light to compare the photo-catalyst performance of BiVO₄,Bi₂WO₆,Bi₂WO₆/BiVO₄ and Bi₂WO₆/BiVO₄/MWCNTs photo-catalysts.In addition,The morphology,physio-chemical properties and specific surface area of the prepared photo-catalyst are investigated by using field emission scanning electron microscopy?Fe-SEM?,transmission electron microscopy?TEM?,X-ray diffraction?XRD?,UV-vis diffuse reflectance spectroscopy?DRS?,and Brunauer-Emmett-Teller?BET?,respectively.The result of the surface area,the band gap and the absorbance ensure that the loading of MWCNTs effectively improves the photo-catalytical performance.The results indicate that the Bi₂WO₆/BiVO₄/MWCNTs nanocomposite photo-catalyst,whose surface area is 35.59 m2/g,the band gap is about 2.0eV and the degradation is researched to 75% within 30 min,95% in 2h,demonstrating best photo-catalytic capability than the other three photo-catalysts,which is may due to the good conductivity effect and the large surface area of MWCNTs.Secondly,the preparation process of Bi₂WO₆/BiVO₄/MWCNTs nanocomposite is optimized through the determination of six influence factors: the different ratio of MWCNTs,the reactiontime,the reaction temperature,the pH value of precursor solution,the calcination temperature and calcination time.Through analyzing the influence of six factors on the morphology,crystalline phase and photo-catalytical performance,the preparation process is confirmed.Similarly,this nanocomposite was investigated by SEM ? XRD and UV-vis.The results were obtained by degrading reactive dyes RB-19,indicating under the condition of the 3:1 doping ratio of Bi₂WO₆/BiVO₄ and MWCNTs,reaction temperature 180?,reaction time 4h,precursor solution p H=7,calcination temperature 500? and calcination time 3h,the nanocomposite photo-catalyst exhibits excellent photo-catalytic performance: 81.5% degradation within 30 min and 91.8%degradation in 1h.In addition,the photo-catalytic efficiency of the nanocomposite still maintains above 85% after 5 recycles of resues.Finally,in order to solve the problem that powder is difficult to reuse in the liquid phase,the alkali decrement polyester fiber is chosen as a carrier.Through the reaction between the carboxyl group of MWCNTs and the hydroxyl group of the polyester with maceration method,the fiber based photo-catalyst was successfully synthesized.Moreover,the surface morphology is characterized by SEM and the irradiation capability is calculated by the degradation of RB-19 under the visible light.On one hand,the impregnation process is optimized.When the dipping temperature is 85?,the dipping time is 3h and the drying temperature is 60?,the maximum capacity of the photo-catalyst on the polyester fiber is 62.35%.On the other hand,the influence of the dye concentration,salt concentration,the pH value of the colorant and non-ionic surfactant on the photo-catalytic properties of the fiber-based photo-catalyst were also researched in this research.The results illustrated that the polyester fiber-base nanocomposite photo-catalyst shows the outstanding photo-catalytic performance with the concentration of colorant is 50mg/L,p H value is 2,without salt and non-ionic surfactant.Furthermore,the photo-catalytic efficiency of the fiber-based photo-catalyst remains stably above 90% even after 7 recycles under the visible light.