| As an efficient technology,advanced oxidation technology has been applied in water treatment.The photocatalytic oxidation technology is one of the most emerging and popular methods with titanium dioxide(TiO2)photocatalyst,which has been widly studied.TiO2 has attracted extensive attention as a photocatalyst due to its chemical stability,safty,non-toxic,high photocatalytic activity and low cost.Therefore,it is a potential photocatalyst and shows a broad application prospect.However,its defects limit its pratical application in wastewater treatment,such as the wide band gap,poor response to visible light,low adsorption capacity,high recombination rate of photogenerated carriers and the difficulties in recycling.In order to overcome these shortcomings,it is critical to modify the TiO2 to gain a novel photocatalyst.In view of this,we made the following improvements in this paper:1.An efficient Ag/AgCl/polydopamine-TiO2 fiber(SCP-TF)photocatalyst was sythesized based on self-supported TiO2 owing to the unique chemical structure and properties of polydopamine(PDA).The Ag/AgCl nanoparticles was prepared and stabily attached on the fibers,where the PDA acted as areducing agent and anchoring agent.The existence of Ag/AgCl nanoparticles was confirmed by textural analysis,FT-IR,XPS,SEM,UV-Vis and PLanalysis.The SCP-TF can responses to visble light and has low recombination rate of photogenerated carriers,which is owing to the Surface Plasmon Resonance effect of Ag0 nanoparticles.The photocatalytic degradation of X-3B was carried out under 1000 W Xe lamp(λ>400 nm).After 120 min of visible-light irradiation,the removal rate of X-3B over SCP-TF is 97%,which is about 4 times higher than TF.The prepared SCP-TF exhibits enhanced visible-light photocatalytic activity and excellent stability in the photodegradation of X-3B.The scavenger experiments results illustrate the ·OH radicals play the most important role in degrading X-3B.According these results,the possible photocalytic mechanism was proposed.2.The hierarchically mesoporous heterojunction CeO2/TiO2 fibers(CTF)was sythesized with mild hydrothermal method.The texture feature analysis shows the hierarchically mesoporous structure of CTF.The pore size diameters of TiO2 is mainly distributed at 12.8 nm and 16.1 nm,and its average pore size is 15.296 nm.However,the pore diameters of 0.25CTF and 0.5CTF was distributed at 3.7 nm,7.5 nm and 11.5 nm,and their average pore diameters were significantly reduced to 7.524 nm and 3.698 nm,respectively.The sufficient pores and large suface area are contributed to the adsorption of pollutants X-3B.Comparing with pure TiO2,the band gap of CTF is obviously reduced,and the recombination of photogenerated carriers has been inhibited.As results,0.5CTF shows excellent adsorption and photocatalytic performance to degradate X-3B,because the hierarchical mesoporous structure increases the ability to adsorb pollutant and the heterostructure narrows the bandgap to response the visible light.3.The Bi doped TiO2 fibers were prepared via sol-gel method,which was based on our previous work.The most suitable ratio of Bi:Ti was determined at 1.5%by adjusting the amount of Bi element doping.At this ratio,the prepared spinning solution has a viscosity and spinnability,so the consequent and recyclable fibers could be prepared with centrifugal spinning method.XRD results show that the Bi elements change the lattice structure of the TiO2 fiber,resulting in a large lattice constant.As the DRS and PL results,B-TF can obsorb visible light due to the doped Bi element.The hybrid energy levels promote the separation of electrons and holes.Under visible light irradiation,the removal efficiency of B-TF for X-3B was significantly improved.As results,the 1.5%B-TF show enhanced photocatalytic performance(87.5%)and the fastest degradation rate to X-3B(k=0.02579 min-1),which is conducive to recovered and reused. |
