The Study On Kapok-Based Activated Carbon Fiber Of Visible Light Catalytic Performance

With the rapid development of the society,the pollution is more serious such as waste water discharge pollution for textile printing and dyeing,automobile exhaust pollution,etc.Therefore,all kinds of management methods and technology are developed.The activated carbon fiber?ACF?is the most widely used because of large specific surface area,fast adsorption rate,large adsorption capacity,medium pore and so on.Three kinds of ACF including Ag doping TiO₂ kapok-based ACF,Mn doping TiO₂kapok-based ACF and multi-walled carbon nanotubes?CNT?loading kapok-based ACF were produced in this thesis.The properties and the structure of the kapok-based ACFs are characterized by FTIR,RAMAN,SEM,XRD,elemental analysis et al.The visible light photocatalytic degradation for the methylene blue of the TiO₂ kapok-based ACFs was studied.The influence of the doping quality on the properties was also investigated and the best doping quality was obtained.The adsorption kinetic of methylene blue on the adsorbent was studied.Firstly,seven Ag doping TiO₂ kapok-based ACFs and kapok-based ACF and TiO₂kapok-based ACFs were prepared by the sol-gel method.The result finds that the structure of ACFs is similar and has a graphite component.The Ag doping is only physical blending without chemical bonding.The visible light photocatalytic degradation for the methylene blue increases owing to the doping Ag.The Ag doping TiO₂ kapok-based ACFs with 0.5%Ag has the best adsorption property and the minimum absorbance.Secondly,six Mn doping TiO₂ kapok-based ACFs were prepared by the sol-gel method.It is found that Mn doping is only physical blending without chemical bonding.The aggregation and crack of TiO₂ and the visible light photocatalytic degradation of methylene blue are improved due to the Mn doping.The adsorption performance at the visible light is the best when the Ti: Mn mole ratio is 1:150.The Mn doping TiO₂ kapok-based ACFs has agood reusable property and light photocatalytic degradation with only 30% decrease of adsorption after five use times.Finally,six CNT loading kapok-based ACFs were prepared by impregnated and loaded CNT with 10²0nm diameter.The results show that the CNT has a physical adhesion and don't generate new functional groups in preparation process.The adsorption performance increases first and then decreases with the increase of the load quality.The kapok-based ACF has the best adsorption property when the CNT content is 12%.The degree of carbonization is high and the activity of the kapok-based ACF is good.The absorption mechanism of the produced three kinds of kapok-based ACF follows the second order kinetics strongly for the liquid phase.When the doping amount is small,the doping Ag or Mn for the TiO₂ kapok-based ACF can generate additional energy levels between the conduction band and valence band of TiO₂,which can reduce the band gap of TiO₂.Therefore,the photocatalytic activity of TiO₂ is improved and the range of the optical response is broadened.When the doping amount is large,the excess Ag or Mn is attached to the TiO₂ surface,which becomes the recombination center of electron and hole.Therefore the photocatalytic activity of TiO₂ is decreased.