Study On Preparation,Modification And Photocatalytic Degradation Of TiO₂ Films In Situ

With the development of industrialization and the improvement of people's living standard,the water pollution caused by various kinds of dye wastewater is becoming a global problem that affects the sustainable development of human beings.Due to the high oxidation efficiency,metal oxide photocatalytic process is generally accepted as an effective method for treating refractory organic compounds.In all kinds of metal oxide,titanium dioxide(Ti O2)because of its chemical and biological inertness,photocatalytic stability,low price,less impact on the environment and can be used for degradation of various organic and inorganic liquid and gas waste.In this paper,Ti O2 films were prepared in situ by microplasma oxidation.Filter is suitable in-situ growth of Ti O2 membrane electrolytic fluid system,with the aim to degradation of rhodamine B material,research of KH2PO4,H2SO4,Na H2PO4,Na2SO4,K2CO3,KOH and Na3PO4 electrolytic fluid system on the film-forming properties and catalytic performance of Ti O2 film.Study of micro plasma oxidation reaction voltage,current,reaction time and concentration of electrolyte,and other process parameters on the photocatalytic efficiency of Ti O2 thin film in situ growth rule,using SEM,AFM,XRD and XPS of Ti O2 film micro morphology,crystal phase composition,elements were analyzed,and the optimization of the micro plasma oxidation of Ti O2 thin films prepared by the process parameters.To improving the performance of the film photocatalytic to electrolyte respectively add Co Cl2,Co(NO3)2and Cd Cl2 inorganic salts,such as preparation of Co2+ and Cd2+ ions doped in situ Ti O2 thin film growth,explore the metal ion doping on the microstructure of the film,crystal phase composition and the composition of elements and the influence law of photocatalytic efficiency,revealing the mechanism of photocatalyticreaction.The research results show that with Na H2PO4,Na2SO4,K2CO3,KOH and Na3PO4 electrolytic liquid ratio,KH2PO4 and H2SO4 as electrolyte can make on in situ titanium matrix to grow a layer of Ti O2 thin film,film layer and high photocatalytic efficiency.However,H2SO4 electrolyte prepared Ti O2 film for longer than KH2PO4 as the electrolyte film time.Since the strong acid electrolyte has a large environmental pollution,the paper USES KH2PO4 as the electrolytic liquid system to prepare Ti O2 films.With KH2PO4 as the electrolytic liquid system,it was screened by process parameters.When the voltage was 360 V,current 0.5a,electrolyte concentration was 0.1mol/L and reaction time was 10 min,the photocatalytic performance of Ti O2 film was better.The SEM photos show that the Ti O2 film has the characteristics of the crater morphology,which is porous,the pore and pore diameter are evenly distributed,and the pore diameter is 200-700 nm.In situ growth of Ti O2 thin films prepared by XRD was mainly composed of anatase,rutile Ti O2 and titanium.In situ growth Ti O2 film was measured by XPS with obvious O1 s and Ti2 p absorption peaks,which proved that the micro-arc oxidation formed Ti O2 film on the surface of Ti substrate.The degradation rate of Ti O2 film to rhodamine B was about43%.After the doping of Co2+ and Cd2+ ion,the pore density of the films was significantly increased,and the pore diameter was even more uniform,which was 100-500 nm.The results of crystal phase composition show that doped Co2+ and Cd2+ ions have little influence on the composition of Ti O2 thin films,and are still made up of anatase,rutile Ti O2 and titanium.According to the XPS spectrum,obvious Co2 p and Cd3 d absorption peaks appear in the doped spectra,indicating that Co2+ and Cd2+ ions have entered the Ti O2 lattice.After the doping of Co2+ and Cd2+ ions,the degradation rate of Ti O2 film to rhodamine B increased by 17.7%,19.7% and 12.07% respectively.By SEM,AFM,XRD,XPS analysis,test results after doping metal ions Ti O2 thin film photocatalytic performance is not caused by the crystal phase composition,but due to the microstructure change,doping of Co2+ and Cd2+ ions can make Ti O2 membrane pore density increased significantly,the aperture size is more uniform,thereby increasing the income of thin film surface,increased the Ti O2 thin film and the reaction rate of degradation of the target,the photocatalytic efficiency improved significantly.