Preparation Of Titanium Dioxide Fiber/activated Carbon Porous Material And Its Use In Photocatalytic Degradation Of Organic Pollutants

Volatile organic compounds?VOCs?toluene poses a great threat to living environment and health of human and animals,remaining to be solved.At present,among all methods for toluene removal,adsorption method is the most widely used,and photocatalysis method is the most potential.Semiconductor material of TiO₂ is the most effective and the best candidate photocatalyst.However,most of TiO₂ materials existing in forms of powder which is difficult to be separated and can cause secondary pollution,are difficult to be practice applied.Additional,there is still a great challenge in effective adsorption and photodegradation of VOCs especially for the high concentrations.Herein,on the research base of TiO₂rods?Ti RDs?,we firstly fabricate Ti O₂ nanofiber/activated carbon?Ti NF/ACF?porous materials by deposition of Ti NFs within ACF felts using three steps hydrothermal method.The FESEM,TEM,XRD,PMI,XPS,BET,UV-Vis and PL were used to characterize and analyze the microstructure,phase structure,pore size distribution,chemical compositions and element valence states,specific surface area,light adsorption ability and fate of electron-hole separations of TiRDs and TiNF/ACF porous materials.Moreover,statistic catalytic reaction were used to evaluate the adsorption and catalytic activities using toluene as degradation object and explore thoroughly the reaction kinetics and synergetic effect mechanism of adsorption and photocatalysis.The contents of this research can be summarized as follows:?1?We prepare micrometre-scale TiRDs via two step hydrothermal method by using titanium nanoparticles?Ti NPs?as titanium source.And the anatase TiRDs with lengths of 2-4?m and diameters of 100-300 nm were originated from the ordered aggregates of many 17.1 nm nanocrystals along the[101]direction.TiRDs posed strong toluene removal ability because of high specific surface area,micro structure,nanometer composition characteristics.The ability of control group of Ti NPs for toluene removal was stronger than Ti RDs during 2 h adsorption experiment and before 15 h catalytic reaction.However,after 15 h photodegradation,TiRDs exhibited higher catalytic rate than Ti NPs due to the photocatalytic activity of TiNPs declined gradually with the reaction time increasing.Moreover,after 21 h catalytic reaction,TiRDs posed better photocatalytic activity than TiNPs,and their corresponding photocatalytic efficiencies of toluene are 68.4%and 66.1%,respectively.?2?We for the first time fabricate TiNF/ACF porous materials by using tetrabutyl titanate?TBT?as titanium source,and ACF as morphology-directing agents.The ultralong Ti NFs with diameters of 30-100 nm and lengths of>200?m were originated from the ordered aggregates of nanocrystals along the[101]direction.The TiNF/ACF porous materials possessed excellent adsorption property for toluene,and the adsorption performances were fit well with pseudo-second-order kinetics model.Their adsorption efficiency reached 98.9%at the toluene concentration of<4600 ppm and 85.6%even at the high concentration of 13800 ppm.Moreover,the synergetic effect between the Ti NFs and ACFs improved remarkably the photodegradation activity of the composites.The ACFs not only increased the quantum efficiency of TiO₂ by hindering the recombination of electron-hole pairs,but also enhanced the light adsorption ability by reducing the TiO₂ band gap energy?E_g?to 2.99 e V.At the toluene concentrations of 115 ppm or 230 ppm,the photocatalytic time in which toluene degraded completely into CO₂ and H₂O was only 5 h or 13 h,respectively.The photodegradation kinetics of toluene matched well with the apparent first-order reaction kinetics model at low concentrations of 115 ppm,while that matched well with the semi-empirical power-law expression equation of CO₂ desorption at high concentration of 690 ppm.Hence,the TiNF/ACF porous materials with excellent adsorption and photocatalytic activities had great application potentials for VOC removal.