Oxidation of diazinon in cns-ZnO/LED photocatalytic process: Catalyst preparation, photocatalytic examination, and toxicity bioassay of oxidation by-products

Abstract

Abstract To enhance the catalytic potential of ZnO in the UV-LED photocatalytic process, ZnO was doped with C, N, and S nonmetals. The doped ZnO was characterized, and its photocatalytic potential was compared with plain ZnO for the degradation and mineralization of diazinon. The characterization analysis of the powder prepared at the calcination temperature of 500 °C indicated the production of a mesoporous cns-doped ZnO (cns-ZnO) with a specific surface area of 4.74 m2/g and crystallite size of 21.4 nm. Photocatalytic experiments were carried out under different experimental conditions. The cns-ZnO prepared at a calcination temperature of 500 °C showed the highest photocatalytic potential of 53.4% for the removal of diazinon at a reaction time of 100 min. The degradation and mineralization rate constants of diazinon in the cns-ZnO/LED process were 0.434 h−1 and 0.202 h−1, respectively; the degradation rate constant of diazinon in ZnO/LED process was 0.0054 h−1. The results of bioassay analysis showed that the cns-ZnO/LED process could reduce the final photoluminance inhibition of the diazinon by 46.4%. The electrical energy needed for one log reduction in the diazinon concentration in the cns-ZnO/LED process was 180.6 kW/m3 that is less than that of the conventional photocatalytic process using UV/ZnO with mercury lamps as radiation source. Accordingly, cns-ZnO is a promising catalyst, which is efficiently activated with UV-LED lamps for the advanced oxidation of emerging water contaminates.