Preparation,Microstructure And Properties Of SiO₂/TiO₂/WO₃ Composite Aerogel

The SiO₂/TiO₂/WO₃ composite aerogels with strong adsorptive capacity and visible-light photocatalytic activity could have high efficiency for removing the organic pollutions due to the synergistic effection of adsorption and photocatalysis.Thus SiO₂/TiO₂/WO₃ composite aerogels had high potential of application in the field of environmental purification.In this paper SiO₂/TiO₂/WO₃ composite aerogels were synthesized via different methods,and the microstructure and properties of the composite aerogels were investigated by differential thermal analyzer?DTA?,Fourier transform infrared spectrometer?FTIR?,X-ray diffraction?XRD?,nitrogen adsorption-desorption,scanning electron microscope?SEM?and transmission electron microscope?TEM?analysis.The adsorption/photocatalytic was evaluated by the adsorption/photocatalytic degradation of Rhodamine B experiment.Silica-titania composite aerogels were synthesized via ambient pressure drying by using water glass and titanium tetrachloride as raw materials.The influences of different heat-treatment on the microstructure and properties of the composite aerogels were investigated.The results indicate that the–CH₃ groups on the surface of silica-titania composite aerogels would transform into-OH groups gradually when the heat-treatment temperature is higher than 450?.In the meantime the composite aerogels network structure would be destroyed gradually and the crystallinity of TiO₂ would be improved with the increase of heat-treatment temperature.With the increase of heat-treatment temperature,the adsorption ability decreases and the photocatalytic activity had a little raised.The SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials with strong adsorption capacity and visible response were prepared via sample hydrothermal synthesis method.The characterization results confirmed that the SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials exhibited good network structure,high specific surface area and pore volume,the1.3STW mesoporous powder samples synthesized from the 50 mL precursor solution containing 1.3g SiO₂ aerogel have the highest specific surface area with 271.3m²/g and pore volume with 0.87 L/g,respectively.The SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials exhibited high adsorption/photocatalytic activity,and the sample 0.9STW-1:3 had highest efficiency which was synthesized from the precursor solution with SiO₂ aerogel 0.9g/50mL and ethanol/water?volume ratio?=1:3.Moreover,the SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials exhibited very good recyclability which still exhibited good adsorptive capacity and photocatalytic activity after 4 cycles.SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials were prepared by using natural material such as starch,leaves,cellulose as template via hydrothermal synthesis method.The characterization results confirmed that the SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials prepared using cellulose as template exhibited the highest specific surface area and pore volume and the adsorption/photocatalytic efficiency for removing the Rhodamine B from water was the highest.The SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials using leaves as template formed irregular morphology similar to leaf cells and exhibited the fastest rate of adsorption.The SiO₂/TiO₂-WO₃ mesoporous photocatalytic materials using starch as template formed comparatively regular sphere and exhibited better photocatalytic activity.SiO₂/TiO₂/WO₃ composite gels were synthesized via sol gel-impregnation adsorption.ThentheSiO₂/TiO₂/WO₃compositeaerogelwerepreparedthroughsurface modification-solvent exchange via ambient pressure drying.The analysis results confirmed that SiO₂/TiO₂/WO₃ composite aerogel exhibited good network structure,high specific surface area with 267m²/g⁵62m²/g.The SiO₂/TiO₂/WO₃ composite aerogel exhibited high adsorption/photo-catalytic activity,the efficiency for removing the Rhodamine B from water washigherthan80%in60minunderdarkroomadsorption.More,the adsorption/photo-catalytic activity improved with the increase of the Ti?SO₄?₂ concentration.SiO₂/TiO₂/WO₃ composite gels were synthesized via sol gel-hydrothermal deposits method.The analysis results confirmed that SiO₂/TiO₂/WO₃ composite aerogel exhibited good network structure and high specific surface area with 228 m²/g⁴58 m²/g.The heat-treated SiO₂/TiO₂/WO₃ composite aerogel exhibited high adsorption/photo-catalytic activity.Moreover the sample with the ammonia amount of 30ml and the W/Ti mol ratio of2%had highest efficiency for removing the Rhodamine B from water,which was 75%in 60min under darkroom adsorption and the Rhodamine B absorbed on the surface of the network were almost decomposed in 180min under visible light irradiation.