Preparation Of Carbon Nitride Graphite ?g-C₃N₄? And Researchofits Magnetic Composites

In recent years,water pollution has received a great deal of attention because there was distinctly increasing trend of sewage discharge.Thus,semiconductor photocatalysis has emerged as a most promising technology for the degradation of the organic contaminants in wastewater due to its excellent properties such as prominent stability,low-cost,and easy separation.In this study,a magnetically separable g-C₃N₄/Fe₃O₄ composites with different and controlled Fe₃O₄ content were successfully synthesized via a facile and economical method,and their visible light photodegradation characters for dyes were studied,the main results in our work are summarized as follows:?1?The g-C₃N₄ was prepared by high temperature calcination,and the effects of precursor,calcination temperature and heating rate to the crystal structure and morphology about g-C₃N₄ were studied.The crystal structure and morphology about g-C₃N₄ were characterized by XRD,FT-IR,TEM and SEM.The results showed that the g-C₃N₄ had high crystallinity,high surface areas,and smooth surface when it was synthesized via melamine under the condition of 550? and 4?/min.?2?The g-C₃N₄/Fe₃O₄ magnetical composites with different Fe₃O₄ content were prepared by coprecipitation method and one-step hydrothermal method.The crystal structure and morphology about g-C₃N₄ were characterized by XRD,FT-IR,TEM and SEM.The results showed that the Fe₃O₄ particles had good dispersibility in g-C₃N₄/Fe₃O₄ composite photo catalyst prepared by one-step hydrothermal method compared with coprecipitation method.Moreover,the Fe₃O₄ and g-C₃N₄ had a strong interaction and formed heterojunction structure,which could efficiently improved separation efficiency of photo-generated electron-hole pairs.?3?The photocatalytic performance of a series of g-C₃N₄/Fe₃O₄ composites which prepared by one-step hydrothermal method were estimated.The results showed that the photocatalytic degradation efficiency of g-C₃N₄/Fe₃O₄ composites was connected with the content of Fe₃O₄ particles,that is,appropriate content of Fe₃O₄ particles could improve g-C₃N₄/Fe₃O₄ photocatalytic degradation efficiency,while excess content of Fe₃O₄ particles had inhibitory effect on g-C₃N₄/Fe₃O₄ photocatalytic degradation efficiency.In this study,the g-C₃N₄/Fe₃O₄ composites showed the highest photocatalytic activity when the Fe₃O₄ particles had a 20.0wt%content.The H-CNFO-20.0 photocatalyst possess prominent photocatalytic activity to MB and RhB,while poor activity to MO,indicating that the g-C₃N₄/Fe₃O₄ composites have a good photocatalytic performance.?4?The g-C₃N₄/Fe₃O₄ photocatalyst was reused some times to ensure its stability.The result shows that the photocatalytic activity of g-C₃N₄/Fe₃O₄ is excellent,and 93%of its initial photocatalytic activity to RhB was still retained after five continuous experiments,indicating the g-C₃N₄/Fe₃O₄ composites have remarkable photocatalytic activity and good stability and have practical application value.