Preparation Of Functionalized G-C₃N₄ Materials And Their Degradation Of Tetracycline Applications

Graphitized carbon nitride(g-C3N4)is a metal-free conjugated polymer with superior chemical stability,non-toxicity and ease of preparation,offering outstanding advantages in drug degradation applications.Functionalised g-C3N4 has a lower band gap and a larger specific surface area,resulting in superior photocatalytic properties.In this paper,functionalised g-C3N4 materials are used for the degradation of tetracycline in water,and the study includes:1.Preparation and TC degradation of tubular g-C3N4 modified with Ag-doped ionic liquidsAg-doped ionic liquids(ILs)modified with tubular g-C3N4(Ag/PILCN)were prepared by hydrothermal,thermal polymerization and photoreduction methods.The surface modification of ILs led to an increase in the specific surface area of g-C3N4(CN)and the introduction of P elements,and the doping of Ag increased the visible light absorption due to its surface plasmon resonance(SPR)effect.Compared with pure g-C3N4,the photocatalytic degradation capacity of Ag/PILCN was greatly enhanced,and the degradation efficiency of tetracycline reached 96.4%within 240 min.The degradation curve conformed to the quasi primary kinetic equation,and the quasi primary kinetic constant was 2.4 times higher than that of pure g-C3N4,and the catalytic performance did not decrease significantly after four cycles.Its improved degradation efficiency for tetracycline was attributed to the synergistic effect of surface modification of ILs and doping of Ag.2.Preparation of SiO2@CN/BTO photocatalytic membranes and TC degradationSiO2@CN/BTO photocatalytic membranes were prepared by electrostatic spinning and solvothermal methods.The structural characterization confirmed that the ribbon CN and bulk Bi4Ti3O12(BTO)were uniformly loaded on the SiO2 film.The SiO2@CN/BTO photocatalytic membrane exhibited efficient degradation of tetracycline under light irradiation,with degradation efficiency up to 97%within 150 min.The degradation was in accordance with quasi primary kinetics,and its quasi primary kinetic constant was 2.2 times that of pure CN,and the catalytic performance did not decrease significantly after four cycles.The improved degradation efficiency of tetracycline may be attributed to the formation of heterojunctions that allow for efficient interfacial electron transfer at the material interface.The photocatalytic membrane improves the limitations of powder catalysts,which are difficult to recover,and is expected to be used for practical pharmaceutical wastewater treatment.3.Preparation of SiO2@CN/BiOBr/BiOI photocatalytic membranes and TC degradationHeterojunctional SiO2@CN/BiOBr/BiOI photocatalytic membranes were prepared by electrostatic spinning technique and solvothermal reaction.Structural characterisation confirmed that red algae-like porous CN and bismuth halide oxide(BiOX)were uniformly loaded on the SiO2 fibrous membrane.the SiO2@CN/BiOBr/BiOI heterojunction membrane exhibited highly efficient photodegradation activity against pharmaceutical contaminants(tetracycline)under light irradiation,removing 100%of tetracycline within 120 min with a quasi primary kinetic constant 6.8 times higher than that of pure CN.The main reason for the improved performance could be the formation of heterojunctions between the red algaelike porous CN and BiOX,thus increasing the efficiency of electron-hole pair separation.This result has great potential for future studies on the degradation of pharmaceutical contaminants.4.Preparation of PAN/CN/BiOCl photocatalytic films and TC degradationFlexible PAN/CN/BiOCl films were prepared using electrostatic spinning technology.Structural characterisation confirmed that the ribbon-like g-C3N4 was present in the PAN fibres and the lamellar BiOCl was wrapped around the outside of the fibres.The films exhibited highly enhanced photocatalytic activity towards tetracycline,with a degradation efficiency of 99%within 100 min and without significant decrease in degradation efficiency when repeated five times.The possible reason for the improved photocatalytic performance was the formation of heterojunctions between the banded porous CN and BiOCl,which reduced the electronhole complex and enhanced the electron-hole separation efficiency.The degradation of other pharmaceutical pollutants,including ciprofloxacin and sulfamethoxazole,by the composite membrane was also investigated and the degradation results were higher than 80%,indicating that the PAN/CN/BiOCl composite membrane is expected to be used in complex pharmaceutical effluents.