[Preparation and characterization of Zn/Cr-LDHs and their removal performances of reactive brilliant orange X-GN].

Zn/Cr-LDHs with cationic ratios of 1:1 to 1:5 were prepared using the co-precipitation method. After preparation of the layered double hydroxides, 2:1 Zn/Cr-LDHs were calcined at 300, 400 and 500 degrees C in a Muffle furnace for 2 h. The obtained mixed oxides are also called calcined layered double hydroxides (Zn/Cr-LDO). Structures of the obtained materials were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, atomic absorption spectrometry and BET analysis. Experiments were then carried out to investigate the removal of reactive brilliant orange X-GN by 2:1 Zn/Cr-LDHs and Zn/Cr-LDO under ultraviolet light and in dark conditions. The results showed that the removal capacity of 2:1 Zn/Cr-LDHs was not affected by ultraviolet light. Under the irradiation of ultraviolet light, the removal rate of reactive brilliant orange X-GN by Zn/Cr-LDO was twice as high as that in dark conditions, which demonstrated its photocatalysis property and its removal of reactive brilliant orange X-GN by the combined action of absorption and photocatalysis.