Ag2S–ZnO – An efficient photocatalyst for the mineralization of Acid Black 1 with UV light

The Ag2S loaded ZnO (Ag2S–ZnO) was successfully synthesized by precipitation of zinc oxalate and Ag2S and calcination of the mixed precipitate at 400 °C for 12 h. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) images, energy dispersive spectra (EDS), diffuse reflectance spectra (DRS) photoluminescence spectra (PL) and BET surface area measurements. The photocatalytic activity of Ag2S–ZnO was investigated for the degradation of Acid Black (AB 1) in aqueous solution using UV light. Ag2S–ZnO is found to be more efficient than commercial ZnO, prepared ZnO and TiO2–P25 at pH 9 for the mineralization of Acid Black 1. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization have been analyzed. Mechanism of degradation by Ag2S–ZnO is proposed. The mineralization of Acid Black 1 has also been confirmed by COD measurements. The catalyst is found to be reusable.

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► The Ag2S–ZnO was successfully synthesized by precipitation–decomposition method.
► This method of preparation gives a homogeneous dispersion of Ag2S in ZnO.
► Ag2S–ZnO is more efficient than commercial ZnO for the mineralization of AB 1.
► The catalyst is found to be reusable.
► Treatment of dye effluent using Ag2S–ZnO will be more economical and eco-friendly.