Synthesis, characterization and application of Cu doped ZnO nanocatalyst for photocatalytic ozonation of textile dye and study of its reusability

Abstract

Highly coloured wastewater generated from textile industries contain exhausted dyestuffs which are generally refractory in nature and resist the conventional treatment methods. The current research work focuses on the synergistic effect of Cu doped ZnO (Cu–ZnO) nanocatalyst in combination with ozonation for the degradation of dyes in the wastewater. Hydrothermal method was used for preparing the nanocatalyst. X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) with Energy dispersive x-ray spectroscopy (EDAX) were used to assess structure and morphological properties of Cu–ZnO. Hexgonal Wurzite structure was confirmed by XRD and the formation of 1D nanorod from FESEM studies. Prepared nanocatalyst in combination with ozone was used for the photocatalytic ozonation (PCO) of Amaranth dye which is taken for the present study. The experiments were conducted by varying ozone dosages (0.12–0.57 g h−1), pH (3–9), catalyst load (0–2 g L−1) and dye concentration (5–50 mg L−1) to optimize nano PCO for degradation of Amaranth. Under optimized conditions, 98% decolourisation in 30 min and 72.4% mineralization in 180 min were achieved. The efficiency and reusability of the catalyst was assessed which showed 24% reduction in the performance after six successive PCO cycles. Based on the above results, the current route is promising alternate for the application of Cu–ZnO based nanocatalyst in combination with ozonation for degradation of recalcitrant dyes in wastewater.