Preparation Of Nanometer Titanium Dioxide/activated Carbon Fiber Felt Three-dimensional Porous Material And Its Adsorption And Photocatalytic Degradation Properties For Toluene

Volatile organic compounds?VOCs?that are emitted from indurtrial facilities and chemical industrial process exist widely in indoor air.The indoor air pollution originated from VOCs cause human health and environmental problems.Toluene,one of most common VOCs in indoor environmens,can enter into blood through lung,skin and gastrointestinal tract,and accumulate in adipose tissue,liver and brain.Because of its adverse effects on human health su ch as sick building syndrome,central nervous system depression and even the cause of death,it is highly urgent to develop novel materials and technologies for toluene removal.In this work,the titanium dioxide/hydroxyapatite?TiO₂/HAP?and titanium dioxide/active carbon fiber felt?TiO₂/ACFF?composites which exhibit excellent adsorption and photodegradation ability are successfully synthesized through hydrothermal method.The phase structure,microtopography,pore size distribution,specific surface area and light adsorption ability of the composites are analyzed.Then,toluene is used as simulated pollutant,TiO₂/HAP and TiO₂/ACFF composite materials are used as photocatalysts,P25,Ti O 2 powders and ACFF are used as control groups to explore the adsorption and photocatalytic activity of composite materials toward toluene.Also,the photocatalytic mechanism of composite materials toward toluene is preliminary explored.The experimental results are shown as follows:?1?The TiO₂/HAP composite powders with different Ti/?Ca+Ti?molar ratios are synthesized through hydrothermal method.The composites are made up of HAP and TiO₂ and the TiO₂ exhibits anatase phase.Morphological SEM analysis indicates that the existence of HAP diminishes the aggregation of TiO₂ particles and leads to their higher dispersion in the composites.The specific surface area s of TiO₂/HAP05 and TiO₂/HAP09 composite materials are 131 and 137 m2/g,respectively.The photocatalytic activity of TiO₂/HAP is online measured under UV illumination.The results show that the photocatalytic oxidation of toluene over TiO₂/HAP is improved in comparsion with pure TiO₂ and HAP powders.When the molar ratio of Ti/?Ca+Ti?is 0.9,the maximum photocatalytic activity of the catalyst is received.The enhanced photocatalytic activity is attributed to the improved TiO₂ dispersion and toluene trapping by the composite materials.?2?The TiO₂/ACFF porous composites are synthesized by the in situ deposition of TiO₂ microspheres on the carbon fibers in ACFF.Interestingly,the TiO₂ microspheres exhibit hierarchical nanostructures constructed by nanocrystals as building blocks.The particle size of the nanocrystal is about 17.8 nm.The TiO₂/ACFF porous composites possess excellent adsorption and photodrgradation properties for toluene because of the synergetic effects between the nanostructured TiO₂ and ACFF.The adsorption efficiencies of the TiO₂/ACFF porous composites reach approximately 98% at the toluene concentration?<1150 ppm?and approximately 77% even at the high concentration of 6900 ppm.Moreover,the ACFF in the TiO₂/ACFF porous composites significantly enhances photocatalytic property for toluene by hindering the recombination of electron-hole pairs,reducing the TiO₂ band gap energy?Eg?to 2.95 e V,and accelerating toluene adsorption.At the toluene concentrations of 230 ppm and 460 ppm,the photocatalytic oxidation efficiency of toluene into CO2 arrives at 100% and 81%,respectively.