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 3mmol revealed the highest photocatalytic degradation efficiency of TC (96.8%) after 120min 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 120min 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.