Visible light driven photocatalytic degradation of organic pollutants in wastewater and real sludge using ZnO–ZnS/Ag 2 O–Ag 2 S nanocomposite

Abstract

Visible light active ZnO–ZnS/Ag2O–Ag2S nanocomposite was synthesized for the photocatalytic decomposition of 2-chlorophenol (2-CP) and complex organic compounds in real sludge. The synthesized catalyst was characterized by X-ray diffraction, Scanning electron microscopy, Raman, UV–visible absorption spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic degradation of 2-CP was highly dependent on the solution pH, initial pollutant concentration and reaction time. The adsorption of 2-CP also plays a vital role in its degradation. The maximum interaction and degradation of 2-CP was found at pH 5. The photocatalytic decomposition of 2-CP decreased from 96 to 55% as its concentration increased from 10 to 100 mg/L. Furthermore, the ZnO-ZnS/Ag2O–Ag2S photocatalyst showed a significant enhancement in sludge solubilization, while the soluble COD increased by more than two times of its initial concentration. About 43% increase in the biogas production (anaerobic) was observed form photocatalytically pretreated sludge compared to raw sludge. These results suggest that the synthesized nanomaterial is an efficient catalyst that can be used for multiple applications such as the degradation of toxic pollutants in wastewater and solubilization of sludge for biogas production.