Preparation Of Zeolite-fixed Environmentally Friendly Titanium Dioxide Photocatalyst And Study Of Its Photocatalytic Performanc

Photocatalysis technology has shown significant advantages in the treatment of organic pollutants in the environment because of its low cost and high degradation performance.Among many semiconductor photocatalysts,titanium dioxide has the advantages of good stability,non-toxic and high reactivity,and has a broad application prospect in the field of photocatalytic degradation of organic pollutants.At present,the defects of titanium dioxide with poor visible light response and low separation efficiency of photogenerated electron-hole pairs have been effectively solved by the metal and non-metal doping and precious metal deposition.However,in the process of photocatalytic degradation of organic matter,the reactive oxygen species generated on the catalyst surface will cause damage to organisms in nature,which severely limits the practical application of photocatalytic degradation of organic pollutants.In this study,we encapsulated the titanium dioxide photocatalyst as the active center of photocatalysis inside the zeolite crystal,and utilized the shape selectivity of zeolite molecular sieve to achieve a photocatalyst that can selectively degrade organic pollutants and is harm Less to organisms in nature.The main research contents are as follows:1.Using polydopamine（PDA）as reducing agent and carbon layer precursor,a large number of platinum quantum dots（Pt QDs）were uniform Ly deposited on the surface of N-doped titanium dioxide nanotubes（N-doped TiO₂ NTs）,and then S-1zeolite shell was fixed by solvent-free way to prepare N-doped TiO₂ NTs@C@Pt@S-1 photocatalyst.After degradation by visible light irradiation for 360 min,the degradation rates of aniline and chlorophyll by N-doped TiO₂ NTs@C@Pt was 100%and 74.8%,respectively,which was 2.1 times and 2.0 times of the original TiO₂ NTs（48.4%and 37.0%）.N-doped TiO₂ NTs@C@Pt@S-1 only degraded 8.2%chlorophyll under visible light,which was one ninth of the degradation effect of N-doped TiO₂NTs@C@Pt,while N-doped TiO₂ NTs@C@Pt@S-1 degraded up to 95.7%aniline.On this basis,we conducted Chlorella biodegradation experiments,which further confirmed the shape selectivity and environmental friendliness of N-doped TiO₂NTs@C@Pt@S-1.2.The Pt-doped P25@Beta Zeolite photocatalyst was prepared by successfully loading Pt QDS onto the P25 TiO₂ photocatalyst by impregnation and immobilizing it inside the Beta zeolite crystal.The loading of platinum quantum dots enlarges the light absorption threshold of P25 and inhibits the photogenerated electron-hole pair recombination,which significantly improves the visible light degradation performance of P25.Under visible light,the degradation rates of aniline and chlorophyll by Pt-doped P25 photocatalytic reaction for 360 min can reach 95.1%and 86.9%.Because of the existence of zeolite sheath,Pt-doped P25@Beta Zeolite can selectively degrade aniline,but does not degrade chlorophyll.After 360 min of visible light degradation,the degradation rate of chlorophyll by Pt-doped P25@Beta Zeolite is only 8.6%,while the degradation rate of aniline is as high as 90.8%.And in the Chlorella biodegradation experiment,Pt-doped P25@Beta Zeolite photocatalyst can degrade aniline and is basically harmless to Chlorella.