Preparation Of Heterogeneous Catalyst With Graphite Phase Carbon Nitride As Carrier And Its Application In Dye Treatment

Due to the shortage of fresh drinking water supply,water treatment technology has become a hot research field,which is a global concern.Among them,the serious pollution of dye wastewater has become an important topic,and researchers have contributed a lot of research results.In order to solve the problem of water pollution,graphite phase carbon nitride（g-C₃N₄）has attracted worldwide attention because of its low preparation cost,good stability,visible light activity and unique two-dimensional structure.However,pure g-C₃N₄still has the problem of low separation efficiency of photogenerated electron-hole pairs,which leads to poor photocatalytic effect.At the beginning of the 21st century,g-C₃N₄heterogeneous catalyst has become a hot research material,which accelerates the separation efficiency of photo-generated charge carriers and improves the photocatalytic activity.Therefore,this paper discusses the following:（1）A ternary CuO-La₂O₃/g-C₃N₄ catalyst was synthesized by impregnation method.Under the irradiation of visible light,H₂O₂ was added to form a photo-assisted Fenton-like catalytic system,and Rhodamine B（Rh B）dye was investigated.The optimum working conditions of CuO-La₂O₃/g-C₃N₄ were determined from the aspects of catalyst dosage,H₂O₂ concentration,pH value and catalyst stability.The catalyst can work in a wide pH range（3-11）,and the removal rate of Rh B is still as high as 98%under neutral conditions.Moreover,it still has high cycle stability after five cycles.In addition,the existence of hydroxyl radical was confirmed by coumarin fluorescence method,and a possible reaction mechanism was proposed according to the reaction basis that photo-generated charge carriers can react with O₂ in air to generate superoxide radical.（2）Another ternary CuO-CeO₂/g-C₃N₄ catalyst was synthesized by impregnation method.The Methyl Orange（MO）dye was investigated in photo-assisted Fenton-like system.Similarly,the optimum working conditions of CuO-CeO₂/g-C₃N₄ were determined from the aspects of catalyst dosage,H₂O₂ concentration,pH value and catalyst reusability.The catalyst can also work in a wide pH range（3-11）,and it is confirmed by ICP test that it still has extremely high activity after five cycles,and the removal rate of MO in the fifth cycle is as high as 98%.In addition,the existence of hydroxyl radical（?OH）and superoxide radical（?O₂^-）was confirmed by electron spin resonance technique and coumarin fluorescence method,and a possible reaction mechanism was proposed.These results indicate that the double charge transfer process formed by the combination of g-C₃N₄ with CuO and La₂O₃/CeO₂ accelerates the Fenton-like process,thus producing more active substances to attack organic dyes.In the photo-assisted Fenton-like reaction system,CuO-La₂O₃/g-C₃N₄ and CuO-CeO₂/g-C₃N₄ catalysts have good practical value and broad application prospects in environmental remediation.