Gold nanoparticles Wells–Dawson heteropolyacid nanocomposite film as an effective nanocatalyst in photocatalytic removal of azo dyes from wastewaters

A novel nanophotochromic film consisting of au nanoparticles and wells–dawson-type heteropolyacid, [h6p2w18o62], was prepared by combination of sol–gel and photoreduction method. this film was characterized by uv–visible spectroscopy, particle size distribution, field emission scanning electron microscopy, and energy dispersive spectroscopy analysis. for the preparation of au nanoparticles, heteropolyacid, [h6p2w18o62] was used in form of composite film as a green reductant and stabilizer. au nanoparticles with particle size in the range of 10–20 nm were synthesized and monodispersed in the nanocomposite using dip coating method. the photocatalytic activity of this composite film was studied in the decolorization of methyl orange (meo) and methyl red (mr) as carcinogenic pollutant dyes using uv irradiation. the pseudofirst order rate constants was established and calculated for these reactions. comparison of this composite film with the prepared composite by preyssler heteropolyacid disclosed that the structure of heteropolyacid can affect loading amount of au nanoparticles.