Synthesis And Photocatalytic Antibacterial Performance Of Magnetic Ag/AgCl/g-C₃N₄

Ag/AgCl/g-C3N4 photocatalyst was synthesized by solvothermal method and photo-assisted reduction method,and then magnetically separable ?-Fe2O3/Ag/AgCl/g-C3N4 was prepared through combination of semiconductor?-Fe2O3.The obtained samples were characterized using variety of techniques to reveal the structure and optical properties.The photocatalytic activity was evaluated by inactivating Escherichia coli(E.coli)under visible-light irradiation.In addition,the disinfection properties and disinfection mechanism of photocatalysts were studied in this paper.The main results were as follows:(1)Ag/AgCl/g-C3N4 composite,a visible-light-driven photocatalyst,was synthesized using solvothermal method and photo-assisted reduction method.The optimum photocatalytic efficiency of Ag/AgCl/g-C3N4 for inactiving E.coli was about 5.17 log.In the solvothermal process,g-C3N4 was prepared under the optimal experiment conditions,such as the molar ratio of chloride to dicyandiamide 8:6, dicyandiamide concentration 0.15 mol/L,solvothermal temperature 180? and solvothermal time 36 h.In the photo-assisted reduction process,the optimal molar ratio of Ag/AgCl to g-C3N4 was 4:50,and the optimal deposition time of Ag/AgCl was 30 min.(2)Ag/AgCl/g-C3N4 exhibited spherical or spherical-like morphology,and Ag/AgCl nanoparticles were well dispersed on the surface of Ag/AgCl/g-C3N4.The composite samples with high crystallinity and purity significantly improved light harvesting ability above 685 nm compared to pure g-C3N4.(3)?-Fe2O3 was combined with Ag/AgCl/g-C3N4 by two-step solvothermal method and photo-assisted reduction method.?-Fe2O3/Ag/AgCl/g-C3N4 displayed a spherical or spherical-like structure,and the absorption in the whole visible light district was strengthened obviously.In addition,the incorporation of ?-Fe2O3 in Ag/AgCl/g-C3N4 resulted in improvements in the disinfection activity due to the continuous transfer of photo-generated electrons,which reached 5.59 log of inactived E.coli cells.(4)?-Fe2O3/Ag/AgCl/g-C3N4 exhibited a certain photocatalytic activity in four cycles and in storaging 45 d.Furthermore,the amount of Ag ion leaking from the composite photocatalyst was very low,and the concentrations of Ag ions leaking almost unchanged with the irradiation time increasing.Therefore,it was proved that?-Fe2O3/Ag/AgCl/g-C3N4 had good stability.(5)There was no E.coli reactivated in 48 h after photocatalytic reaction,indicating a good continued antibacterial activity of photocatalysts.So it is a promising visible-light-driven photocatalyst for cleaning microbes in water treatment.(6)Hydroxyl radical(· OH)and hydrogen peroxide(H2O2)were the main oxidation active groups in the disinfection process,and the Ag ions leaking from?-Fe2O3/Ag/AgCl/g-C3N4 also exhibited bactericidal effect.Specifically,reactive species and Ag ions could attack the cell membrane,damage cellular proteins,enzymes and DNA,causing the death of E.coli cell.