Photocatalytic degradation of 2,4,6-trichlorophenol using lanthanum doped ZnO in aqueous suspension

La-doped ZnO nano particles with different La contents were prepared by co-precipitation method using the precursors of zinc and lanthanum. The XRD results indicated that the particle size of La-doped ZnO is much smaller as compared to that of pure ZnO and decreases with increasing La loading. The effect of La loading on the photocatalytic activity of La-doped ZnO in the degradation of 2,4,6-trichlorophenol (TCP) was studied and the results are compared with the pure ZnO and TiO2. The results showed that the rate of degradation of TCP over La-doped ZnO is much higher as compared to that of pure ZnO and TiO2 and increases with increasing La loading upto 0.8 wt% and then decreases. Moreover, the relative photonic efficiency value of La-doped ZnO is relatively higher as compared to undoped ZnO. Among the catalyst studied, 0.8 wt% La-doped ZnO was the most active, showing high relative photonic efficiencies and high photocatalytic activity for the degradation of TCP. La doping in ZnO is highly effective and can significantly enhance the photocatalytic degradation and mineralization of TCP. The enhancement of photocatalytic activity of La-doped ZnO samples is mainly due to their smaller particle size and capability for reducing the electron hole pair recombination. Moreover, the increase of the TCP adsorption over La-doped ZnO samples may also be related for their high photocatalytic activity. (c) 2006 Elsevier B.V. All rights reserved.