Study On Modification Of Graphitic Carbon Nitride And Its Photocatalytic Degradation Of Sulfonamides

In recent decades,sulfonamides（SAs）have attracted extensive attention due to their ecotoxicity and resistance to bacteria,which have progressively become persistent organic pollutants in the environment.As a low energy advanced oxidation processes,the visible light photocatalytic technology is an extremely convenient and promising method which is expected to address growing antibiotic contamination in the environment,which could take advantage of the solar light directly.In this work,two kinds photocatalysts based on g-C₃N₄combining intrinsic with extrinsic way were prepared,alcohol-modified g-C₃N₄-based photocatalysts and Gd-doped g-C₃N₄ photocatalysts respectively.The results showed those photocatalysts can significantly improve the degradation of SAs.The major results are as follows:Four monohydric alcohol were used as solvents,urea was pretreatment with solvothermal reaction initially,and then alcohol-modified g-C₃N₄-based photocatalysts were prepared by high temperature thermal polymerization.The results indicated that those four kinds of catalysts modified possessed properties enhanced of photoelectricity and charges transfer.Among them,the sample CN（I）showed optimal morphology,crystal structure and photoelectric properties.In the experiments of the degradation of four kinds SAs sewage,obviously,CN（I）demonstrated a pretty good stability and a stronger degradation efficiency comparing with the bulk g-C₃N₄.It was mainly because the alcohol modification process doped a certain amount of highly electronegative O element into CN（I）and optimized the basic chemical structure of the catalyst,which improved its photocatalytic performance against four kinds of SAs.Gd modify g-C₃N₄ photocatalysts（HECN-x Gd）were prepared using alcohol as solvent by alcohols assisted solvothermal-thermal polymerization method.Gd dispersed on the surface of HECN-x Gd homogeneously in the form of nano metallic oxide clusters.Meanwhile,the special 4f level structure of Gd further strengthened its ability to absorb visible light.In the experiments of the degradation of Sulfamerazine（SMR）,HECN-x Gd demonstrated a significant improvement comparing with the bulk g-C₃N₄.Among them,HECN-0.15Gd performed a highest degradation efficiency at 98%and reaction rate constant at 0.0216 minute^-1.The TOC test demonstrated HECN-0.15Gd got ability with deep oxidation to sulfamerazine.Through characterization and capture experiments,it was proved that the main active species of photocatalytic degradation of SMR was superoxide radical（·O₂^-）.