Study On Preparation And Photocatalytic Properties Of Zn-Al Hydroxides And Zn-Al Composite Metal Oxides

Zinc-aluminum Hydrotalcite(Zn-Al-LDHs) have been synthesized by co-precipitation method. Zinc-aluminum complex metal oxides(Zn O/Zn Al2O4) were also prepared using Zn-Al-LDHs as precursor under definite calcining temperatures. The morphological, structural, thermal, optical and adsorption properties of the samples were characterized by XRD, TEM, FT-IR, TG-DSC, BET and UV-Vis respectively. The photocatalytic activities were evaluated via a probe reaction to degrade Rhodamine B. Finally, the photocatalytic activities of Dye-sensitized zinc-aluminum complex metal oxides were evaluated by the degradation of phenol under visible light.The results of XRD, TEM and FT-IR showed that the as-prepared sample was zinc aluminum carbonate Hydrotalcite; BET analysis results indicated that the sample possesses mesoporous structure, and its specific area varies in the range of 45~60 m2·g-1; UV-Vis analysis results revealed its light absorption is poor; the data of Rhodamine B degradation stated its photocatalytic activity was relatively poor under xenon lamp.Zinc-aluminum complex metal oxides were made from Zn-Al-LDHs. Calcination temperature and zinc/aluminum mole ratios were discussed with respect to the influence of catalyst photocatalytic performance. The TG-DSC, TEM, XRD and FT-IR analysis results demonstrated that Zn O/Zn Al2O4 was generated when the calcinations temperature was 600℃. BET analysis results indicated that the sample possesses mesoporous structure. UV-Vis analysis results revealed that the catalyst has a good light absorption performance when the calcining temperature was 650℃ and Zn/Al mole ratio was 5:1. The Rhodamine B degradation rate can reach 97.5% in 120 min.Dye-sensitized Zn O/Zn Al2O4 catalyst was synthesized using Rhodamine B and Eosin Y as sensitizers, and the optimum condition was explored by single factor experiments. The XRD results showed that crystal state did not change after the sensitization. The results of FT-IR and UV-Vis showed that there were hydrogen bonds between catalyst and sensitizer. The visible light absorption spectral range and performance was enhanced. Visible light photocatalytic degradation experimental results showed that the phenol degradation rates of Rhodamine B and Eosin Y sensitized catalyst was 90% and 98% respectively.