Navegando por Autor "Petkowicz, Diego Ivan"
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Artigo Bentonites impregnated with TiO2 for photodegradation of methylene blue(Elsevier, 2010-05) Rossetto, Enéderson; Petkowicz, Diego Ivan; Santos, João Henrique Zimnoch dos; Pergher, Sibele Berenice Castellã; Penha, Fábio GarciaFour bentonites and one diatomite from Rio Negro (Argentina) were used as supports for titanium oxide (TiO2). The materials were characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, textural analysis by nitrogen adsorption, elemental analysis and diffuse reflectance spectroscopy. The specific surface areas calculated by the BET method were 76, 46, 80, and 31 for the bentonites and 153 m2/g for diatomite and were not changed by impregnation with TiO2. SEM analysis revealed agglomerates, probably due to titania domains on the surface. The properties of the lamellar materials were maintained after TiO2 impregnation, and all materials showed methylene blue photodegradation activity. The bentonites showed a higher activity than the commercial catalyst P25, likely due to the TiO2 distribution and better accessibility.Artigo Catalytic photodegradation of dyes by in situ zeolite-supported titania(Elsevier, 2010-04-15) Petkowicz, Diego Ivan; Pergher, Sibele Berenice Castellã; Silva, Carlos Daniel Silva da; Rocha, Zênis Novais da; Santos, João Henrique Zimnoch dosThe degradation of dyes (methylene blue, direct blue 71, direct yellow 8) by a series of titania-supported catalysts generated in situ via the impregnation of TiCl4 onto a series of zeolite, which was synthesized using rice husks as the silicon source, was individually evaluated. After calcination, the resulting supported catalysts were characterized by X-ray diffraction spectrometry, ultraviolet–visible diffuse reflectance spectroscopy, diffuse reflectance and transmittance infrared Fourier transform spectroscopy, energy dispersive X-ray scanning electron microscopy, small angle X-ray scattering and differential pulse voltammetry. The titania generated is present in the anatase phase, without affecting the zeolite framework. Catalyst activity was shown to be comparable to that of the commercial P-25 catalyst after 1 h of UV light exposition. Monitoring the catalyst performance of several batches of material showed that P-25 provided the highest photodecomposition until the third cycle. On the other hand, the activity of the in situ-supported titania catalyst, in spite of showing lower catalytic activity, remained roughly constant up to the fifth cycle. This suggests that the catalyst generated in situ is more suitable for both filtering and reuse.