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This work demonstrates the efficiency of a hybrid photocatalysis/ultrafiltration process to eliminate or reduce the contents of synthetic dyes in water. The process involves highly active photocatalytic ceramic ultrafiltration (UF) membranes prepared with the deposition of various photocatalysts on the external and internal (pore) surface of UF mono-channel monoliths. A main challenge consists in swapping from the conventional slurry-type photocatalytic purification technology to a novel photocatalytic membrane filtration technology, using the most prominent recently developed TiO 2 based nanomaterials. With this obbective, highly hydroxylated anatase TiO 2 was deposited on ceramic monoliths by applying sol-gel (dip-coating) techniques. Novel materials comprising modified TiO 2 nanocrystals covered with an organic shell layer as well as partially reduced graphene oxide-TiO 2 composites were synthesized and stabilized on the monoliths with the target to develop visible light responding catalytic membranes. The photocatalytic filtration experiments took place

Nanocomposites of polyvinyl alcohol and ZnO were prepared using the solution casting method. ZnO nanoparticles with hexagonal wurtzite structure and mean sizes of 59, 82 and 150 nm were prepared by thermal decomposition of zinc acetate dihydrate. The synthesized crystals were characterized by X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Optical properties of the nanocomposites were determined using UV–visible absorption spectroscopy. The results showed that all samples appeared near band edge absorption close to the bulk value. Furthermore, broadband dielectric spectroscopy, at ambient temperature, was employed in order to investigate the effect of mean particle size upon interfacial relaxation phenomena. Dielectric data provide evidence that interfacial polarization, which is present in all three nanocomposite films, shifts to higher frequencies and its intensity is decreasing as the mean nanoparticle diameter is also decreasing. Finally, exploiting the Cole–Davidson approach, becomes evident, that interfacial polarization process acquires a more symmetric form, tending to a pure Debye relaxation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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