Preparation Of Modified G-C₃N₄ And Its Photocatalytic Degradation Of Dye RhB

With the mass production and application of dyes,the wastewater produced by them is complicated in composition,varied in water quality and quantity,and difficult to be treated.It is a great challenge to choose a green and efficient method to treat dyeing wastewater.Photocatalytic technology can remove pollutants in water only under the irradiation of sunlight,and can be used to hydrolyze and produce hydrogen and degrade various pollutants in water environment.As a new type of semiconductor photocatalytic material,g-C3N4 has the advantages of simple preparation method,cheap preparation materials and high utilization of visible light.In view of the disadvantages of g-C3N4,such as low specific surface area and high photogenic electron hole compound rate,two modification methods were adopted to treat rhodamine B wastewater as the target pollutant to improve the photocatalytic performance of g-C3N4,and the reaction mechanism was discussed,and the following conclusions were mainly drawn:(1)Firstly,bulk g-C3N4 was prepared with melamine as the precursor,and the bulk g-C3N4 was separated into g-C3N4 nanosheets by calcining at high temperature.SEM,XRD,FT-IR,TG,BET,XPS,UV-Vis and PL were used to analyze the composition,microstructure,pore structure,thermal stability and optical properties of the samples.It was found that after calcination at high temperature,g-C3N4 nanocrystalline was significantly weakened and had a higher specific surface area(83.0291 m2/g),which provided more adsorption and photocatalytic activity sites.In addition,the decrease of fluorescence intensity of composite materials is conducive to the migration of photogenic carriers and the efficiency of photogenic electron hole separation.(2)The photocatalytic degradation of RhB by g-C3N4 nanometer sheets modified by different calcination temperatures and times has been improved to a certain extent.The best results were obtained when the secondary calcination temperature was 550? and the calcination time was 6h.RhB degradation conforms to the curve of primary degradation,and the degradation rate constant of g-C3N4 after high temperature modification is 0.03318 min-1,4.9 times that of the original g-C3N4.Trapping experiments are used to detection the predominant active species in the RhB degradation reaction system.In that case,we can conclude the·O2-may be the major active species in the photocatalytic reaction.g-C3N4 nanometer sheet has good cycling stability.(3)ATP/g-C3N4 composite photocatalyst intercalated by ATP was prepared by calcining attapulgite and melamine by clay modification.By means of SEM,XRD,FT-IR,BET,XPS,UV-Vis,PL and other characterization methods,it was found that the interlayer effect of ATP improved the internal structure of g-C3N4,which not only increased the specific surface area and provided more active photocatalytic sites,but also shortened the movement distance of photogenic electron holes and improved the photocatalytic effect.In addition,the composite of ATP introduced hydroxyl group,which increased the adsorption capacity of the composite material.(4)The composite material after ATP intercalation has good photocatalytic effect.When the mass ratio of ATP to g-C3N4 was 0.04:1,the catalytic degradation performance of RhB was the best,which is 2.33 times that of the original g-C3N4.The removal effect of RhB is up to 99%after 180min of light reaction.Trapping experiments are used to detection the predominant active species in the RhB degradation reaction system.We can conclude the·O2-may be the major active species in the photocatalytic reaction.ATP/g-C3N4 has good cycling stability.