Preparation Of G-C₃N₄/TiO₂ Composite Photocatalyst And Photocatalytic Degradation Of Sulfamethazine

Nano-TiO₂ photocatalyst has many notable advantages,such as stable structure,innocuity,harmlessness,low cost and excellent photocatalytic performance.It is one of the most concerned Semiconductor Photocatalysts in recent years and it has broad potential and application prospect.But the size of the wide band gap?Eg?is 3.2eV,corresponding to the absorption wavelength length is 387.5nm and the length range of the absorption band is not within the range of visible light,it shows that TiO₂ can only response in the UV region range,but the ultraviolet light?wavelength less than 380nm?corresponding to the energy accounted for only 3.39%of the total energy of the solar spectrum the scope,it is shown that TiO₂ as a photocatalyst has a low energy utilization problem,which greatly restricts the application of TiO₂ in practical research.In addition,the photo-induced carrier?electron-hole?of TiO₂ is easily compound,and the photocatalytic degradation efficiency is reduced to a large extent.G-C₃N₄ was a novel non-metallic semiconductor material,it has many obvious advantages by doing reseach,the most response is that it can be on light visible response with wide forbidden band about 2.7 eV,and it was equipped with chemical stability and thermal stability.However,there are still low quantum efficiency,small surface area and other disadvantages.Therefore,in this study,TiO₂ and g-C₃N₄ were organically combined to prepare new g-C₃N₄/TiO₂ composite photocatalyst materials,which greatly improved the application scope of photocatalytic technology.The main research results of this paper are as follows.?1?Using a simple and fast calcining method of directly heating melamine and commercial TiO₂ mixtures to prepare the g-C₃N₄/TiO₂ composite photocatalysts.Adding ultra pure water to a mixture of melamine and industrial TiO₂ with a certain mass ratio and stirring 30min with magnetic force,then put it in the oven to 70 degrees C drying for 24 hours,the solid after drying into ceramic mortar grinding and 100mm aperture sieve,then a mixture after the screen placed in there 550 high temperature calcined alumina crucible inside and in the muffle furnace,the heating rate of calcination is 9DEG/min,calcination time of 5h,until the sample is cooled to room temperature when removed,and then milled into powder,to obtain g-C₃N₄/TiO₂ composite photocatalyst.At the same time,to study the effect of different synthesis conditions on the photocatalytic degradation effect in visible light as Rhodamine B for degradation of pollutants,explore the optimal preparation conditions,the results showed that the quality of the melamine and TiO₂ ratio is 4:1,the calcination temperature is 550,the calcination time is 5h,the photocatalytic degradation of RhB by g-C₃N₄/TiO₂ can reach the best effect.?2?The materials of g-C₃N₄/TiO₂ composite photocatalyst were characterized by some chemical instruments,such as X-ray diffraction,it can be abbreviated as XRD,fourier transform infrared spectroscopy,abbreviated as FT-IR,UV-visible diffused reflectance spectroscopy abbreviated as UV-Vis,specific surface area and pore size distribution abbreviated as BET-BJH and scanning electron microscope abbreviated as SEM.Based on the characterization of XRD and FT-IR has confirmed the existence of g-C₃N₄.It can be observed that TiO₂ was distributed on layered g-C₃N₄.The absorption sideband of g-C₃N₄/TiO₂ was red-shift.It implied g-C₃N₄/TiO₂ can enhance photocatalytic activity,separation of electron-hole and reduce the recombination of photo-induced carrier.?3?The paper study that g-C₃N₄/TiO₂ composite photocatalyst photocatalytic degradation kinetics of sulfamethazine?SMT?factors and photocatalytic degradation effect?the initial solution pH,ionic strength,temperature,repeated times of the test?in the visible light.The results show that SMT is stable in the solution,and has good light stability.It is difficult to be degraded by visible light directly.Under visible light,TiO₂is difficult to directly and effectively degrade SMT,while the synthesized g-C₃N₄/TiO₂has good photocatalytic degradation effect on SMT under visible light.Compared with TiO₂,g-C₃N₄/TiO₂ has wider visible light response range and larger specific surface area.Under neutral or acidic conditions,the effect of g-C₃N₄/TiO₂ photocatalytic degradation of SMT is better than that of alkaline conditions.The change of temperature also has a certain influence on the photocatalytic degradation process,but the effect is not significant.The synthetic g-C₃N₄/TiO₂ has excellent reusability.The study of degradation mechanism showed that the bioactive species that degrade SMT were O₂^-and h⁺,and h⁺played a major role.