Photocatalytic Activity of ZnO Nanoparticles (Bare, Doped and Co-doped with Mg and La) in the Removal of Rhodamine B from Aqueous Solutions by UVC Irradiation

Background & objectives: The organic dyes are environmental pollutants that pour into water sources by industrial wastewater. It is necessary to develop effective methods for removing pollutants. The aim of this study was to evaluate photocatalytic efficiency of bare ZnO nanoparticles doped with Mg and La (1 to 6% by weight) and Mg 5% -La 5% / ZnO and Mg6%-La4% / ZnO nanoparticles in the removal of Rhodamine B from water solution by UVC irradiation. Methods: In this study, nanoparticles were synthesized by the sol-gel method. Their photocatalytic activity was investigated by UVC irradiation to remove Rhodamine B in batch photoreactor. The concentration of Rhodamine B in aqueous solutions was measured by the determination of its absorption at the maximum wavelength of 554 nm with a visible-ultraviolet spectrophotometer. The removal amount in the presence of nanoparticles in 21 min of UVC irradiation was analyzed. In addition, a suitable kinetic model for the photocatalytic activity was investigated. Results: After 21 min UVC irradiation, the percentage of Rhodamine B removal from 11.5% (absence of nanoparticles) to 72.84% (presence of ZnO), 94.36% (presence of Mg 5% / ZnO), 88.54% (presence of La4% / ZnO) and 96.23% (presence of Mg5%-La5% / ZnO). The kinetic constants of active nanoparticles were also calculated. Conclusion: The results of the study show that ZnO nanoparticles are effective as a photocatalyst for the removal of Rhodamine B from aqueous solutions under UVC irradiation, by doped and co-doped ZnO with Mg2+ and La3+ ions enhance the efficiency of nanoparticles in the removal of Rhodamine B. Also, results indicated that the kinetic model followed from the pseudo-first order.