Effect of La dopant on the photocatalytic efficiency of activated ZnO nanopowders

Activated ZnO powder was obtained by an original patented procedure and doped with 0.5, 1 and 1.5 wt % La to improve the photocatalytic performance. The crystalline structure, surface morphology and specific surface area were investigated by X -ray diffractometer (XRD), scanning electron microscopy (SEM) and single point Brunauer -Emmett -Teller (BET) method. The XRD analysis of the oxide samples illustrates the formation of wurtzite ZnO. Increasing of La concentration results in higher degree crystallinity of the doped ZnO samples . The doped and non- doped ZnO crystallite sizes are in the range of 54÷57nm. Doping with La leads to increase of specific surface area compared to non- doped ZnO. The course of the photocatalytic reaction was followed spectrophotometrically based on the maximum absorbance wavelength of the model pollutant Reactive Black 5 (RB5). The samples doped with 1.5 wt % La exhibited the highest efficiency for the photocatalytic degradation of RB5 under UV illumination due to the higher degree of crystallinity, formation of solid solution and higher specific surface area. Key words: La -doped ZnO nanoparticles, photocatalysis, Reactive Black 5 azodye, waste water discoloration