Stduy On The Photocatalytic Degradation Of Dyes By Graphitic Carbon Nitride Under Visible Light And The Mechanism

In this paper,graphitic carbon nitride was prepared by using a cheap raw material of urea as precursor.The photocatalytic degradation of various dyes,including rhodamine B,sulforhodamine B and methylene blue,under visible light was studied.The effects of pH,light intensity and other factors on performance of photocatalytic degradation were investigated.The degradation mechanism of graphitic carbon nitride was investigated by in situ FTIR.The main conclusions are as follows:?1?Results of characterization test by BET and SEM show that the specific surface area and pore volume of graphitic carbon nitride prepared at high temperature increase significantly,and the microstructure changes from bulk to layered structure.Simultaneously,results of FTIR,XRD and XPS showed that the crystallinity and degree of polymerization of graphitic carbon nitride were improved by high temperature preparation of catalyst.The DRS also proved that the catalyst prepared in higher temperature had stronger light absorption ability and better photocatalytic activity.?2?Graphitic carbon nitride has excellent degradation ability to rhodamine B,sulforhodamine B and methylene under visible light,and the degradation performance of rhodamine B can reach more than 70%in 35 minutes;the degradation performance of rhodamine B can be improved under acidic conditions and high light intensity.?3?A method of In situ FTIR in liquid phase was established.The process of photocatalytic degradation of rhodamine B by graphitic carbon nitride was detected by in situ FTIR.The results showed that the deethylation of rhodamine B occurred during the photocatalytic degradation.It was found that the structure of rhodamine B changed from aromatic amine?Ar-N?to aromatic secondary amine?Ar-NH?and aromatic primary amine?Ar-NH₂?,and finally released into the solution in the form of-NH₂.