Photocatalytic Oxidative Degradation Of Antibiotic Contaminants In The Coastal Zone Water Environment Based On G-C₃N₄ Composites

China has 18,000 kilometres of coastline and ensuring the environmental ecology of the coastal zone is of great importance to the development of the country's fishing and livestock industry,military and global trade.Antibiotics are widely used as they can quickly kill germs and protect aquaculture organisms.As antibiotics have become more popular,a series of issues have arisen.For example,tetracycline antibiotics are hard-to-degrade,environmentally harmful organic pollutant,which can be very harmful to soil,water bodies and organisms.Due to management and technical reasons,wastewater containing tetracyclines is discharged into natural watersheds such as rivers and groundwater,which will eventually flow into the sea,causing serious damage to the ecology of the coastal zone environment and detrimental to the agricultural economy.However,conventional wastewater treatment technologies are not able to achieve the desired results and there is an urgent need to develop efficient treatment methods.At present,advanced oxidation technology has become one of the most popular technologies for solving difficult to degrade organic polluted wastewater,and one of the promising developments is semiconductor photocatalysis and its derivatives for efficient oxidation technology in water treatment.It is environmentally friendly,highly efficient,energy saving,zero secondary pollution and can completely degrade pollution,which is not the case with traditional pollutant treatment methods.The key to such technologies is the development of photocatalytic materials with efficient pollutant degradation performance and no pollution.In this paper,the g-C₃N₄composite MoS₂-QDs semiconductor photocatalyst has the problems of high electron-hole recombination rate,poor visible light absorption,and low processing efficiency,and the g-C₃N₄ composite MoS₂/C-QDs semiconductor photocatalyst was prepared.In order to achieve efficient treatment of organic pollutants,environmental purification issues such as the visible light response/degradation of antibiotics organic pollutants have been studied.At the same time,the chemical energy released during the degradation of pollutants was studied.g-C₃N₄ is a new type of non-metallic photocatalytic material.Compared with conventional Ti O₂ photocatalysts,g-C₃N₄ has a wider absorption spectrum and does not require UV light and can act as a photocatalyst only under normal visible light;however,its electrical conductivity is low and its specific surface area is small.Further upgrading is required.First,prepared pure g-C₃N₄,and then used hydrothermal method to dope different proportions of MoS₂-QDs(quantum dots)and C-QDs into amorphous g-C₃N₄,and then conduct crystallography,morphology,and spectroscopy.Spectroscopic characterization,and then several materials will be subjected to photocatalytic degradation experiments under the irradiation of a full-band xenon light source,and the pollutant degradation performance of different materials will be compared.After experimental research,it is found that the C series of g-C₃N₄(CNC3)semiconductor photocatalytic materials doped with a molar ratio of 30%MoS₂-QDs have the best degradation performance,MoS₂ series doped g-C₃N₄(CNM4)semiconductor photocatalytic materials with a molar ratio of 40%MoS₂-QDs have the best degradation performance.The degradation efficiency of CNM4 to 25mg/L tetracycline hydrochloride hydrochloride is 99%in 50 minutes.After determining the best performing material,crystallographic and morphological characterisation was carried out to observe the morphological and physical changes.The degradation and performance enhancement mechanisms were demonstrated by spectroscopic and energy spectroscopic and photoelectrochemical characterisation results.