Study on catalytic degradation of sulfamethoxazole with g-C3N4/TiO2 under visible light irradiation
The composite photocatalytic materials of g-C3N4/TiO2 were prepared with high temperature calcination method using TiO2 particles and melamine as feedstocks,and the removal of sulfonamide antibiotics by g-C3N4/TiO2 in bionic ecosystem was studied.g-C3N4/TiO2 was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and ultraviolet-visible spectrophotometer(UV-vis DRS).The photocatalytic degradation of sulfamethoxazole(SMX)in solution by g-C3N4/TiO2 under visible light irradiation was studied.Results show that g-C3N4/TiO2 has good photocatalytic activity.Under visible light irradiation,the removal rate of SMX with its initial concentration of 200 μg∙L-1 can reach 84.3%at the dosage of g-C3N4/TiO2 = 0.2 g∙L-1.Under the same conditions,g-C3N4 and TiO2 can only remove 21.0%and 16.0%of SMX,respectively,while 95.35%of SMX can be removed in the bionic system at the dosage of g-C3N4/TiO2 = 12.37 g∙m-2.The possible degradation pathways of SMX are proposed according to mass spectrometry analysis including S—N bond cleavage,C—N bond cleavage,S—C bond cleavage,hydroxylation of SMX and nitration of amino groups in SMX.The two possible intermediates are p-aminobenzenesulfonamide and 3-amino-5-methylisoxazole.
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