Silver (Ag) doped graphitic carbon nitride (g-C3N4) photocatalyst for enhanced degradation of Ciprofloxacin (CIP) under visible light irradiation

Abstract

Pharmaceutical industry wastewater is causing an increased risk of resistant pharmaceutical micropollutants (PMP) e.g. antibiotic resistant bacteria (super bug) in the ecosystem. Amongst variety of wastewater treatment approaches, Advanced oxidation processes (AOPs) employing photocatalysis provides a cost-effective and sustainable approach for fixation of PMP in an economical and efficient manner to counter the potential risks. Until today, tremendous efforts have been made to trig the performance of photocatalytic wastewater treatment, with the key focus on development of cost-effective, efficient and a moderately stable photocatalyst. Such attempts succeeded with different types of photocatalysts using different synthesis techniques. In recent years, graphitic carbon nitride (GCN) has emerged as one of the cost effective, moderately stable, nontoxic and efficient photocatalyst, and has been scarcely studied specifically for pharmaceutical micropollutants (PMPs) degradation. Hence, considering these factors alongside the facile synthesis and moderate optical absorption of GCN, an effort was made in the present work with effective customization of GCN i.e. silver (Ag) doping to extend light absorption in visible light range which may enhance the photocatalytic performance for Ciprofloxacin (CIP) degradation. The optimization of photocatalytic performance was executed with varied Ag dopant content to obtain an optimum sample with supreme photocatalytic activity for the maximum degradation of CIP, a common antibiotic. The best Ag-doped GCN sample (0.1 AGCN) exhibits a photocatalytic degradation efficiency of 84%, which is 2.15 times greater than pure GCN (39%). The obtained results showed that the strategy of Ag doping substantially enhances the photocatalytic performance, thus offering an efficient mean for developing visible light active photocatalyst for PMP removal and encouraging further research. The photocatalytic performance of the prepared samples was evaluated by degradation of CIP under visible light irradiation. Several characterization techniques were used to characterize and analyze the prepared samples, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, UV Visible absorption, and Photoluminescence (PL) spectroscopy.