Study On Preparation, Adsorption And Photocatalytic Performance Of Polyoxometalates Intercalated Layered Double Hydroxides

Polyoxometalates-intercalated layered double hydroxides (LDHs-POMs) is a class ofclay materials with positively charged metal-oxide layers, and the layer surface charges isbalanced by polyoxometalates anions. In this paper, we synthesized several new LDHs-POMsby aqueous ion exchange of a Mg-Al LDH, Zn-Al LDH and Zn-Al-Fe LDH precursor innitrate form. The physicochemical properties of the product were characterized by themethods of ICP, XRD, IR, TG-DTA and cyclic voltammetry. LDHs-POMs have been used forthe remocal of dye from aqueous solutions via adsorption and photocatalysis.1. Heteropoly blue-intercalated layered double hydroxide (HB-LDH) was obtained byaqueous ion exchange of a Zn-Al LDH precursor in nitrate form with the reducedpolyoxometalate anions [PW10Mo2O40]5-. The physicochemical properties of the product werecharacterized by the methods of powder X-ray diffraction, infrared spectroscopy, and cyclicvoltammetry. The HB-LDH has been used for the removal of cationic dye methylene blue(MB) from aqueous solutions via adsorption. The intercalation of large cluster anion[PW10Mo2O40]5-into LDH could induce the adsorption to cationic dye of MB, obviously. TheHB-LDH shows much higher cationic dye adsorption capacity than pure LDH and themaximum adsorption capacity Qmaxof MB onto ZnAl-PW10Mo2is30.87mg/g.2. ZnAlFe layered double hydroxides (ZnAlFe-NO3) with Zn:Al:Fe ratio (1:1:0.2) wasobtained by the coprecipitation method and tested as photocatalysts for methylene blue (MB)degradation.[CoW12O40]5-and [P2W17O62]10-were been intercalated in ZnAlFe-NO3byionexchange. The intercalation of large cluster anion into ZnAlFe-LDH could induce theadsorption to cationic dye of MB. The ZnAlFe-NO3and ZnAlFe-CoW12were goodphotocatalysts for methylene blue (MB) degradation.3. Waugh type polyoxometalates [MnMo9O32]6--intercalated layered double hydroxidewas obtained by aqueous ion exchange of a Zn-Al LDH precursor in nitrate form with thereduced polyoxometalate anions [MnMo9O32]6-. The physicochemical properties of theproduct were characterized by the methods of ICP, XRD, IR. ZnAl-MnMo9was tested asphotocatalysts for methylene orange (MO) degradation.4. We report the preparation and characterization of anion-pillared layered doublehydroxide MgAl-SiW9Ni3. The physicochemical properties of the product were characterizedby the methods of ICP, XRD, IR. The investigation of catalytic performance on this sampleexhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide.