Eco-friendly hybrid Paper-AgBr-TiO2 for efficient photocatalytic aerobic mineralization of ethanol.

In this study, a facile and effective route to prepare hybrid photocatalysts (paper-TiO2, paper-TiO2-AgBr and paper-AgBr-TiO2) has been reported. The preparation procedure consisted of the direct adsorption of the previously synthesized titania nanoparticles (TiO2 sol) to generate the TiO2 nanosphere and the immersion process in an aqueous suspension of AgBr to form the AgBr nanoclusters on paper fibers. The synthesis technology is economic, efficient, environmentally friendly and easy to implement even at industrial scale. A cellulose-based structure with well dispersed TiO2 particles of around 1 µm and a pseudo-liquid coating of Ag+ and AgBr species was obtained. All the prepared photocatalysts demonstrated effective photocatalytic performance in gaseous phase ethanol degradation with simulated sunlight illumination, through the direct mineralization to CO2 and the parallel reaction via acetaldehyde degradation. A relevant improvement in the photocatalytic activity was noticed when TiO2 was associated with AgBr nanocrystals, with a higher effect observed when AgBr was loaded onto the paper surface prior to TiO2. Ag-Ti interaction reduces the pair recombination rate and increases the available charge carriers generating reactive OH- radicals from both Ag-species and TiO2, and O2- radicals from Ag+-AgBr species, which would be involved in the ethanol degradation process.

Surface modification of H-ferrierite by reaction with triethoxysilane.

The interaction of triethoxysilane (TES) with H-ferrierite (H-FER) and its effects on acidity have been investigated by infrared spectroscopy. TES adsorbs only on the external surface of H-FER and allows the almost complete disappearance of the external silanol groups. New SiH groups are formed which appear to be inactive in acid-base interactions. The adsorption of propionitrile, which diffuses into the zeolitic channels, provides evidence for the lack of substantial perturbation of the strongly acidic internal bridging OH groups. On the contrary, the adsorption of the hindered basic probe molecule o-toluonitrile, which cannot penetrate the FER channels, shows that not only terminal silanols but also Al3+ Lewis acid sites present on the external surface of H-FER almost totally disappear after TES treatment. Treatment with TES seems to allow virtually the total deactivation of the H-FER external surface.