Research On Photocatalytic Degradation Of Typical Antibiotics With Carbon Nitride And Its Composites

Antibiotics would harm human health and affect ecological balance and it has attracted widely attention from researchers.Green solar-driven photocatalytic technology especially the visible-light driven semiconductor technology has been the research hotspot in emergency organic pollutants.Graphite carbon nitride（g/C₃N₄）as an efficient metal-free photocatalyst with good visible light absorption capacity（450 nm-460 nm）and lower price has been widely used in organic degradation.However,it is still challenging to design photocatalytic materials effectively and selectively for typical antibiotics which are difficult to degrade,such as amoxicillin and lincomycin.In this study,the optical characteristics of g/C₃N₄ was changed mainly by adjusting the energy band,optimizing the charge extraction,modifying the cocatalyst,and forming heterojunction strategies.The composites were synthesized successfully to degrade typical antibiotics,amoxicillin and lincomycin.The efficient degradation rate of antibiotics degradation was pursuing firstly and then the productors,degradation pathway and mechanisms were analyzed.The photocatalysts were controlled synthesized through micro-morphology,crystal structure,surface chemical composition and optical features detecting.The photocatalytic activity was elevated by dynamic experiments.Mainly active species was detectived to explore the degradation pathway and photocatalytic mechanisms.The g/C₃N₄series materials were synthesized successfully to improve the migration and conversion of photo-generated carriers.Finally,the composite photocatalysts have a selective and efficient photocatalytic capability for amoxicillin and lincomycin degradation were achieved.Firstly,according to the strategies of building heterojunction structure,the Zn O-g/C₃N₄photocatalyst was synthesized to degrade amoxicillin under visible light with different methods,synthesizing g/C₃N₄ firstly,synthesizing g/C₃N₄ and Zn O together and synthesizing Zn O firstly.The optical properties of Zn O-g/C₃N₄ synthesized by different methods are inconsistent.Materials synthesized by first synthesizing Zn O can form heterojunction at the interface between Zn O and g/C₃N₄,which improves the light absorption performance and the charge separation ability.Compared with g/C₃N₄,the degradation rate of amoxicillin by Zn O-g/C₃N₄ has increased about 11 times.The main active substances produced by different synthetic methods were different.In the optimal way,·OH and h⁺are the main active species.Secondly,according to the strategies of doping element and loading cocatalyst,the CD-r GO-O-g/C₃N₄ photocatalyst was successfully synthesized to degrade lincomycin under visible light.Compared with g/C₃N₄,the degradation rate of lincomycin by CD-r GO-O-g/C₃N₄was improved by 17 times.During the degradation process,active materials including·O₂^-,·OH,and h⁺have different roles in different photocatalysts degradation systems.The intermediate H₂O₂ plays an important role in the photocatalytic process,and its detailed functions and sources are clarified for the first time.The synergistic effect of oxygen doping,CD and r GO on degradation of lincomycin and the degradation mechanism are further analyzed.This research systematically studied the efficiency,degradation mechanism and degradation pathway of the typical antibiotics,amoxicillin and lincomycin by g/C₃N₄-based photocatalyst.The preliminary establishment of amoxicillin and the rapid and efficient pretreatment technology of lincomycin provides a possible method for antibiotic removal.