Preparation Of GC₃N₄-based Composite Material And Its Photocatalytic Degradation Of Bisphenol A

As a typical non-metallic photocatalytic semiconductor material,graphite phase nitride carbon(g-C3N4)is widely appreciated by scientists due to its visible-light response and appropriate band gap.However,the photogenerated carriers of single g-C3N4 have a higher recombination rate,which limits its photocatalytic activity.In order to expand the response range of g-C3N4 to visible light and reduce the recombination rate of the photogenerated carriers,melamine was selected as the precursor,and g-C3N4 was prepared by calcination method.Ag3PO4/g-C3N4 composites were prepared by coprecipitation method.Moreover,Bi2Ti2O7/g-C3N4 composites were prepared by solvothermal method and AgBiO3/g-C3N4 composites were prepared by ion exchange method.These prepared composites were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis)diffuse reflectance spectroscopy(DRS)and photoluminescence spectra(PL).Bisphenol A(BPA)was selected as the target contaminant,and which was photocatalytic degradated by Ag3PO4/g-C3N4,Bi2Ti2O7/g-C3N4 and AgBiO3/g-C3N4 composites,respectively.Besides,the photocatalytic oxidation mechanisms were also dicussed.1.The results of composites characterization show that Ag3PO4,Bi2Ti2O7 and AgBiO3 materials are uniformly deposited on the surface of g-C3N4.The utilization efficiency of visible light is enhanced by prepared nanocomposites.2.The prepared Ag3PO4/g-C3N4 composites were applied in the photodegradation of BPA,and several significant affecting factors of photocatalytic oxidation were discussed such as the catalyst components,pH,the dosage of catalyst,the initial concentration of BPA and the salinity.Moreover,the photo reaction mechanism has been preliminary explained.The experimental results show that:(1)When Ag3PO4 and g-C3N4 have a mass ratio of 1:3(APC-25),The BPA degradation efficiency can reach 92.81%under the optimized experimental factors with 180 min visible-light irradiation.(2)The optimized experimental factors are that the system pH is at 7,the dosage of APC-25 is 5 mg,and the initial concentration of BPA is 10 mg·L-1.(3)The photocatalytic degradation of BPA by APC-25 follows pseudo-first-order kinetics.(4)Different trapping agents were added in the reaction system to capture the active oxidation species.The results show that the superoxide free radical(·O2-)plays a leading role in the degradation process.3.The photocatalytic degradation of Bi2Ti2O7/g-C3N4 was applied to degrade the BPA solution.The experimental results showed that:(1)When the mass ratio of Bi2Ti2O7 and g-C3N4 is 1:1(BTC-50),the degradation efficiency of BPA can achieve the best result.93.32%bisphenol A can be photodegraded by 15 mg BTC-50 under 300 min visible-light irradiation,when the solution pH is at 7,and the concentration of BPA is 5 mg·L-1.(2)The photocatalytic degradation of BPA by BTC-50 follows pseudo-first-order kinetics.(3)The active specie ·O2-was found to play a key role during the photocatalytic reaction.(4)The photocatalytic activity of BTC-50 composite is not observably changed after multicycles.4.The photocatalytic degradation of AgBiO3/g-C3N4 was applied to remove the BPA.The experimental results showed that:(1)When the mass ratio of AgBiO3 and g-C3N4 is 1:1(ABC-50),the removal efficiency of BPA is about 95.75%after 180 min visible-light irradiation by ABC-50,when the solution pH is at 7,the dosage of BTC-50 is 20 mg,and the concentration of BPA is 10 mg· L-1.(2)The photocatalytic degradation of BPA by ABC-50 follows pseudo-first-order kinetics.(3)The active species ·O2-·OH and h+ all play the key roles during the photocatalytic reaction in the process of photocatalytic degradation of BPA by ABC-50 composite.