Research On The Liquid Phase Stripping And Photocatalytic Activity Of G-C₃N₄ Nanosheets

Photocatalyst can degrade most of the organic compounde which are harmful for human body and environment.And photocatalysis possesses high degradation rate without secondary pollution to the environment.Therefore,photocatalysis is an effective method to solve the current water pollution problem.In this paper,bulk g-C₃N₄ was prepared by thermal polycondensation method,and the photocatalytic activity of g-C₃N₄ was further improved by using sulfuric acid liquid phase stripping,ammonia liquid phase stripping and nitric acid pretreatment,respectively,and the cprresponding photocatalytic performances and mechanism were explored as well.Main achievements of this paper are as follows:?1?g-C₃N₄ nanosheets with good disperribility were prepared using sulfuric acid liquid phase stripping.The morphology,element valence,functional groups and photocatalytic properties of the products were characterized by transmission electron microscopy?TEM?,photoelectron spectroscopy?XPS?,fourier transform infrared spectroscopy?FTIR?and XPA-7 photochemical reaction apparatus.The photocatalytic performances were studied by photocatalytic degrading rhodamine B.The results showed that particle size of g-C₃N₄ nanosheets became small and the agglomeration phenomenon became weaker,and the morphology of the nanostructures varied with the sulfuric acid/ethanol ratio.The g-C₃N₄ nanosheets show high UV-photocatalytic activity,especially the g-C₃N₄?1:10 for sulfuric acid/ethanol ratio?nanosheets,which can completely degrade 10 ml 10 mg/L rhodamine B within 60 min,6 times than that of g-C₃N₄.?2?Ammonia liquid stripping was used to prepare g-C₃N₄ nanosheets.The g-C₃N₄ nanosheets with different morphologies were obtained by changing the stripping temperature.The morphology,functional groups and valence states of g-C₃N₄ nanosheets were characterized by TEM,FTIR and XPS,respecticely.The obtained g-C₃N₄ nanosheets at different stripping temperatures can completely degrade 10 mg/L rhodamine B solution within 120 min under visible light irradiation,and the g-C₃N₄?30??nanosheets shows the highest degradation rate of 60% in 30 min.?3?In order to further improve the photocatalytic performance of g-C₃N₄-based nanostructures,melamine was pretreated with nitric acid with different concentrations.The g-C₃N₄ nanosheets were obtained by thermal polycondensation method with the preatreated melamine as the source material.The morphology,functional groups,elemental valence and photocatalytic activity of g-C₃N₄ nanosheets were studied by SEM,FTIR,XPS and XPA-7 photochemical reaction apparatus,respectively.The size distribution obtained g-C₃N₄ nanosheets became uniform and smaller.The photocatalytic performances of the products were improved,and 10 ml 10 mg/L rhodamine B can be completely degraded within 16 min by all resulting g-C₃N₄ products.The optimized nanosheets achieved the highest degradation rate of 85% within 4 min.?4?Melamine pretreatment and ammonia liquid stripping were combined to prepare g-C₃N₄?1.3 mol/L nitric acid?/30 ? and g-C₃N₄?1.3 mol/L nitric acid?/100 ? nanosheets.The morphology,functional groups,elemental valence and photocatalytic activity of g-C₃N₄ nanosheets were characterized.However,the secondary liquid phase stripping of ammonia does not improve the photocatalytic performance of the sample.?5?The g-C₃N₄?1.3 mol/L nitric acid?/475°C nanosheets were prepared by thermal oxidation of g-C₃N₄?1.3 mol/L nitric acid?in air.The morphology,functional groups,element valence and photocatalytic properties of g-C₃N₄?1.3 mol/L nitric acid?/475°C nanosheets were characterized.The visible light photocatalytic performance of the g-C₃N₄?1.3 mol/L nitric acid?/475°C nanosheets is further improved compared to that of g-C₃N₄?1.3 mol/L nitric acid?,which can completely degrade 10 ml 10 mg/L rhodamine B within 4 min.