Cellulose Based Catalytic Activated Carbon Fiber Preparation And Its Photo-catalytic Performance

Recently,water pollution is getting more and more serious.Photocatalytic technology is an effective method in degrading polluted wastewater.Not only because this way can be operated simply but also has no secondary pollution to the environment.It is especially suitable for the treatment of some toxic organic compounds,which is difficult to biodegrade.Titanium dioxide is a non-toxic,stable catalyst and has good photocatalytic properties.It is widely used in the field of environmental cleanliness.But TiO₂ is difficult to recycle and easy to fall off.Therefore,the photocatalyst immobilization can not only overcome the poor stability in the suspension phase,but also can solve the difficult problem about catalyst recovery.However,the degradation efficiency of the traditional immobilization method is relatively low.In this paper,activated carbon based catalysts with microporous and high specific surface area were prepared from cellulose-based raw materials with a large amount of active hydroxyl groups on the surface.In this paper,the catalysts were fabricated by template method and electrospinning method,The prepared catalytic fibers has special structure and own the large specific surface area and strong adsorption performance.These properties are beneficial to increase the photocatalytic performance.Overall,the catalysts can greatly enhance the photocatalytic degradation effect in the organic wastewater treatment.Main content of the project:1.A novel TiO₂-wrapped nanofiber composite catalyst,which possessed a unique porous structure and mixed crystalline phase,was prepared by the combination of superficial sol–gel and post-calcination processes.By means of the superficial sol–gel process,TiO₂ layers were deposited on the surface of each nanofiber-like cellulose fiber,and then the TiO₂-wrapped nanofiber composite catalysts were calcined at different temperatures under a nitrogen atmosphere.With temperature increasing,the original cotton nanofiber composites were converted into porous carbon nanofiber catalysts wrapped by a TiO₂ mixed crystalline phase,which was accompanied by a crystal transformation.The photocatalytic activity of the new catalysts was evaluated by the degradation of methylene blue?MB?under ultraviolet?UV?irradiation.The results demonstrated that the new catalysts had good photocatalytic ability,and the TNC-700 catalyst showed superior photocatalytic ability compared with the other catalysts;the new catalysts had a unique porous structure,high specific surface area,and mixed crystalline phase.Additionally,the synergistic photocatalytic effect of the TiO₂ and activated carbon nanofiber resulted in the efficient degradation of organic pollutants in water or air.2.Nanocellulose basedcatalytic nanofibershavepreparatedby the electrospinning technique andfurther calcinations.This part discusses the effect of electrostatic spinning process parameters on the morphology of Nanocellulose based catalytic nanofibers,and investigated effects of different variable values on their morphology and photocatalytic properties.The results show that the voltage of 21 KV and receiving distance of 15 cm is for better for the electrospinning process.The suitable mass fraction of cellulose acetate is 18%and the surfaces of nanocellulose based catalytic nano-fibers are smooth in the diameters of about 200±50 nm.Futhermore,the catalysts treated by activators can obviously improve the adsorbability.3.A porous carbon based composite nanofibers was fabricated by electrospinning method and further calcinations.Firstly,the cellulose based composite nanofibers containing tetrabutyltitanate and urea were prepared by electrospinning method.Then the cellulose based composite nanofibers calcined at 550?in N₂atmosphere were changed into the porous carbon based composite nanofibers,which contained porous carbon materials,TiO₂ nanoparticles from tetrabutyltitanate and nitrogen element from low-cost urea.The as-prepared porous carbon based nanofibers showed superior photocatalytic activity compared with degussa P25 and pure TiO₂/activated carbon fiber?ACF?composites under visible light irradiation??>400nm?.When the content of urea was up to 4%,the as-prepared nanofibers showed the highest photocatalytic activity,and successfully degraded 98%of the methylene blue?MB?in 3 h.The porous carbon nanofibers calcined show superior absorption performance,nitrogen element from urea efficiently extends the absorption wavelength of TiO₂ to visible-light region,the TiO₂ calcined has a high percentage of photocatalytic reactive facets.The dopant of low-cost urea was favorable for separating photo-generated electron-hole pairs more effectively and enhancing photocatalytic activity.The results confirm that the as-prepared nanofibers containing porous carbon,TiO₂ and nitrogen element show a superior synergistic effect for improvement of photocatalytic activity under visible-light irradiation.This study provides a novel nanocomposite material with energy transformation and superior photocatalysis under visible light,and offers a simple valid preparation method for effective synthesis of nonmetal-metal oxide nanofiber photocatalysts,which can be potentially used in the fields of photocatalysis,purification and green chemistry.