Modification Of Graphite Carbon Nitride And Its Application In Catalytic Oxidation Degradation Of Pollutants

Fenton is a relatively clean and green method for degradate contaminants.Among them,graphite phase carbon nitride?g-C₃N₄?is a new type of catalyst that has received much attention in recent years.The structure of graphite carbon nitride is similar to that of graphite,and it has received great attention in the field of photocatalysis due to its excellent chemical stability and tunable electronic properties.It contains six nitrogen-to-electron"nitrogen-cans",which are ideal sites for chemical modification.However,its shortcomings such as small light absorption threshold and easy recombination of photogenerated carriers limit its application.Therefore,the photocatalytic activity of the novel nanocomposites prepared by the method of doping metal Fe is improved,and the morphology of the catalyst is improved by a series of characterization.The research was carried out as follows:?1?Catalytic Degradation of Sulfamethoxazole by monoatomic iron-doped graphite phase carbon nitride compositesUrea was used as a precursor to iron-synthesized monoatomic iron-doped graphite phase-carbon nitride composite?SA-Fe/g-C₃N₄?by adding hemin.At the same time,the catalyst was characterized by a series of characterization,such as scanning electron microscope?SEM?,transmission electron microscope?TEM?,high-angle annular dark field image-scanning transmission microscope?HADDF-STEM?,X-ray powder diffractometer?XRD?.X-ray photoelectron spectroscopy?XPS?,fluorescence spectroscopy?PL?,ultraviolet-visible spectroscopy?UV-vis?,and the like.From these characterizations it was found that iron in the material was loaded in g-C₃N₄ in a single atom form.It was found that under visible light,SA-Fe/g-C₃N₄ with a hemin loading of 0.75%had the best catalytic degradation of sulfamethoxazole?SMX?in photo-Fenton system,and the degradation efficiency of pollutants after 40 min can reach 99%.At the same time,we also carried out a cycle experiment and found that the degradation efficiency can still reach more than 85%after 5 cycles,which indicates that the stability and repeatability of the material is better.?2?Study on Degradation of Bisphenol A by Persulfate Degradation of Monoatomic Iron-Doped Graphite Phase Carbon Nitride CompositesStill using the above materials,the material and g-C₃N₄ activated persulfate?PS?were degraded under visible light to degrade bisphenol A.The study found that the catalytic activity of SA-Fe/g-C₃N₄ with a hemin loading of 0.25%was the best,and the efficiency of degrading bisphenol A in the Fenton-like system was 99%.The SA-Fe/g-C3N4 composite also has high stability and still has good catalytic activity after 5 cycles.?3?Study on catalytic degradation of sulfamethoxine by iron-doped graphite phase carbon nitride compositesUsing thiourea as precursor,adding the biomimetic material hemin,and Fe/g-C₃N₄composite was synthesized by one-pot pyrolysis.It is found that g-C₃N₄ after doping with iron has better catalytic oxidation performance,which is mainly due to the fact that doped iron can improve the absorption ability of visible light and suppress the recombination probability of electron-hole.In addition,sulfadimethoxine?SDM?was selected as the target pollutant for photo-Fenton degradation.The results showed that the degradation of Fe/g-C₃N₄composites was much higher than that of g-C₃N₄.The best quality ratio of hemin and g-C₃N₄is 0.25%,and the degradation efficiency is 99%after 40 min,which indicates that g-C₃N₄ has been successfully modified in this paper.The optimum conditions for degrading SDM are pH=3,catalyst concentration is 0.2 g/L,hydrogen peroxide concentration is 60 mM,and sulfamethoxine concentration is 20 mg/L.