Nitric acid activation of La-doped ZnO photocatalyst for water decontamination
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2015-01-01
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Abstract
An original patented procedure was applied to obtain activated ZnO powder and then it was doped with 1.5 mass % La to improve the photocatalytic performance. The effect of a nitric acid treatment (index a.t.) of the La/ZnO investigated by comparing with the non-treated La/ZnO samples, manifests a higher photocatalytic efficiency of the former in the oxidative degradation of the model textile wastewater pollutant azo dye Reactive Black 5. The acidically treated La/ZnO powders have been obtained by impregnation in 0.1 M HNO3 acidic solution, followed by thermal treatment at 100oC, 350°C and 500°C. The materials have been characterized by the XRD, XPS and single point BET methods. The XRD analysis shows the presence of three crystallographic phases: wurtzite, Zn(NO3)(OH).H2O and 4ZnO(OH)2.Zn(NO3)2.H2O. The XPS data give evidence of N-atoms in ZnO after the acidic treatment. The best photocatalytic performance is shown by the La/ZnO a.t. dried at 100°C due to its highest nitrogen content.