| Antibiotics,as a class of drugs in pharmaceuticals and personal care products（PPCPs）,are continuously released into the water environment due to their frequent misuse,becoming harmful pollutants.The presence of residual antibiotics in the aquatic environment inevitably alters the metabolic activities of microbial communities,induces the formation of antibiotic resistance genes,and ultimately poses a serious threat to ecosystems and human health.Regrettably,traditional wastewater treatment plants do not yet have the technology to completely remove antibiotic contaminants,resulting in antibiotics being released into natural water bodies without adequate elimination.In this context,green photocatalytic advanced oxidation technology is expected to become a practical method for antibiotic wastewater treatment due to its high efficiency and environmental protection characteristics.Among many photocatalysts,carbon nitride,as a low-cost,high-stability photocatalytic material,has great potential in photocatalytic wastewater treatment.However,pristine carbon nitride has low carrier separation efficiency,weak visible light absorption and small specific surface area,which limit its application in photocatalytic wastewater treatment.Therefore,in this thesis,the inherent shortcomings of carbon nitride were improved by constructing an intramolecular electron donor-acceptor structure and optimizing surface topography.Besides,the photocatalytic degradation activity and the mechanism of its improving performance were studied.The main research contents are as follows:（1）Through the modification method of thermal copolymerization,creatinine-derived molecules were doped into the carbon nitride framework,and the carbon nitride intramolecular electron donor-acceptor（D-A）structure was constructed.The successful doping of creatinine-derived molecules and the successful construction of intramolecular D-A structures were confirmed by X-ray photoelectron spectroscopy,UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy.Density functional theory calculations indicated that the doped creatinine-derived molecules acted as electron donors in the copolymers,while revealing the direction of electron flow within the copolymers.This strategy enabled carbon nitride to form a porous morphology,expand the light absorption range and accelerate electron transport,while maintaining the high reduction potential of carbon nitride to generate oxygen radicals.The synthesized copolymer degraded sulfisoxazole at a rate of 5.6 times that of pristine carbon nitride under blue LED light and 15.3 times that of pristine carbon nitride under green LED light,and exhibited good stability and degradation universality.In addition,the active species quenching experiment and electron spin resonance characterization showed that the copolymer had a stronger ability to generate superoxide radical（·O2-）,and the degradation pathway of sulfisoxazole was speculated by liquid chromatography-mass spectrometry analysis.（2）Through the modification method of surface regulation,the morphology of carbon nitride was optimized into one-dimensional hollow nanotube（Co-CNt）,and the cobalt was introduced into nanotube to synthesize cobalt-doped hollow tubular carbon nitride.It was confirmed by electron microscopy characterization that tubular morphology was successfully synthesized.It was revealed by infrared spectroscopy and X-ray photoelectron spectroscopy that tubular topography had a larger open surface to adsorb water molecules.It was confirmed by photoluminescence spectroscopy that the design of structure and the introduction of cobalt facilitated the separation of photogenerated carriers in multiple steps.The experiments showed that the degradation rate of sulfisoxazole by Co-CNt under blue LED light was 21.7 times higher than that of the pristine carbon nitride,and the main active specie for degradation was·O2-. |
