In this study, La and Mg doped, and co-doped ZnO nanoparticles were prepared using the sol-gel method. The prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and N2 physisorption techniques. The XRD results indicated that the prepared nanoparticles can be well adopted by the hexagonal wurtzite structure crystal and there are no second impurity peaks. Studies of the FESEM, EDX and TEM have shown that the samples have uniform spherical-like morphology with a homogenous distribution. The incorporation of La and Mg into the ZnO lattice had no effect on the morphology of the nanoparticles, but a reduction in the size of the grains (≈ 14 nm to ≈ 7 nm) was observed due to the insertion of these ions. The results of N2 physisorption indicated that there was an increase in BET surface area and pore volume for doped and co-doped samples. The results of DRS showed an increase in band gap energy and a blue shift at the absorption edge for doped and co-doped samples. The photocatalytic activity of the prepared catalysts was evaluated in the removal of RhB under UVA irradiation. The results showed that Mg5%-La5%/ZnO had the highest photoactivity (91.18 %) among all samples.

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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 visibleultraviolet 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 Mg 2+ and La 3+ 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.