Ag-doped graphitic carbon nitride photocatalyst with remarkably enhanced photocatalytic activity towards antibiotic in hospital wastewater under solar light

Abstract

In this study a novel Ag-doped graphitic carbon nitride (g-C3N4) photocatalyst was synthesized and applied as high efficient material under solar light towards emerging antibiotic pollutant in hospital wastewater. The tetracycline (TC) was chosen as a target pollutant and the content of Ag doping at 3 mmol revealed the highest photocatalytic degradation efficiency of TC (96.8%) after 120 min under solar light irradiation. The photoluminescence and UV–vis analysis confirmed the enhancement of charge separation and transfer in the graphitic carbon structure after Ag-doping. The removal efficiency of TC using g-C3N4 and Ag-doped g-C3N4 (AgCN) under dark conditions was only 25.6 and 31.8%, respectively. While under solar light conditions, the removal efficiency of TC increased to 68.3 and 96.8% for g-C3N4 and AgCN, respectively. The reusability process showed that AgCN displayed extremely high stability after 6 cycles without significant drop in antibiotic degradation efficiency. The application of AgCN was tested for treatment of TC from hospital wastewater and it showed high removal efficiency of 89.6% within 120 min reaction time. In addition, the intermediates generated and reduction of total organic carbon (TOC) during the photocatalytic reaction were detected to support information of possible TC removal mechanism.