Sonocatalytic degradation of Congo red by using green synthesized silver doped zinc oxide nanoparticles

Abstract

In this work, silver doped zinc oxide nanoparticles were successfully prepared using green synthesis. The prepared samples were then characterized by the means of X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectroscopy and field-emission scanning electron microscopy (FESEM). The samples were found to have high crystallinity and purity. A reduction in the size was observed in silver doped ZnO nanoparticles as compared to pristine ZnO nanoparticles due to the lattice distortion induced by dopant. The introduction of silver dopant into the lattice structure also led to band gap narrowing. Evaluation of sonocatalytic degradation was carried out through parameter study including the types of plants used to synthesize silver doped ZnO nanoparticles, initial dye concentration (20 mg/L to 40 mg/L), catalyst loading (0.75 g/L to 2.0 g/L) and different types of dye. ZnO nanoparticles synthesized using Asian pigeonwings flower with 5 wt% of silver doping performed the best in the sonocatalytic degradation among all the samples. The degradation efficiency of Congo red was optimized at operating conditions with 20 mg/L of initial dye concentration and 1.75 g/L of catalyst loading. In addition, the biosynthesized silver doped ZnO nanoparticles show excellent sonocatalytic performance in the degradation of various types of dye. In short, this work provides exposure for developing the removal of hazardous organic dye pollutants using green synthesized ZnO nanoparticles with silver doping under ultrasound irradiation.