Hydrothermal synthesis of ZnO photocatalyst for detoxification of anionic azo dyes and antibiotic

Abstract The ZnO photocatalysts were prepared by a hydrothermal method by using the Zn2+/OH− mole ratio of 1:5, 1:12, and 1:18 denoted as ZnO-1, ZnO-2, and ZnO-3, respectively. All prepared photocatalysts showed the hexagonal phase with the band gap energy of around 3.19 eV and the specific surface area of about 10.6 m2g-1. These photocatalysts remained stable even heating up to 1000 °C. Interestingly, the synthesized ZnO-1photocatalyst provided the lowest PL intensity among all prepared photocatalysts. This indicated the lowest electron-hole recombination rate at the interface. Therefore, this sample exhibited the highest photoactivity. The complete photodegradation of RR141, CR, and OFL pollutants after 20, 60 and 180 min of solar light irradiation, respectively, was obtained. The photodegradation of the pollutants correlated well with the first-order kinetics model. The corresponding rate constants of 0.1432, 0.0494 and 0.0304 min−1 toward degradation of RR141, CR and OFL, respectively, were reported. The stability of the ZnO-1 photocatalyst after three times of use was confirmed. The ZnO-1 photocatalyst still provided high performance even after the third cycle indicating its promising reusability. The photogenerated electron played a vital role in removal of the pollutants. The present research demonstrates a promising route for fabrication of ZnO photocatalyst with high efficiency for detoxification of organic pollutants in wastewater.