## Macro-mesoporous sulfated titanium dioxide from sol-gel associated to emulsion templates for photocatalysis application

Reference Presenter Authors
(Institution)
Abstract
17-032 Paula Glazielli Paulino Moraes Moraes, P.G.(Instituto de Química/UNESP); Alves-Rosa, M.A.(Instituto de Química/UNESP); Pulcinelli, S.H.(Instituto de Química/UNESP); Santilli, C.V.(Instituto de Química/UNESP); Titanium dioxide has attracted great interest due to the diversity of its properties. This oxide can exhibit anatase and rutile crystalline structures, which consist of Ti octahedra (${\mathrm{TiO}}_{6}$) arranged in different ways. The rutile phase is thermodynamically stable at temperatures close to the ambient whereas the anatase turns into rutile at temperatures between 600 and 700 °C. The sulfation of ${\mathrm{TiO}}_{2}$ is an alternative to stabilize the anatase phase, the more photoactive phase of titania, the surface area upon high-temperature calcination treatment as well as to promote the porous structure. In this study, the proposed process aims to combine the formation of porous titanium dioxide and its sulfation in a single step by sol-gel process combined with emulsion templates; to shape the porous structure surfactants and oil were added under stirring in order to generate a macro-mesoporous structure from emulsion templates, generating photoactive ceramic foams after drying and thermal treatment. According to the structural characterization by XRD the addition of sulfate species leads to a stabilization of anatase phase, since single-phase materials with anatase as only phase were observed even at 700 °C for sulfated materials. However, for non-sulfated ${\mathrm{TiO}}_{2}$ calcined at 700 °C, the rutile phase was observed as a second phase. FTIR spectra show bands around 1050-1250 ${\mathrm{cm}}^{-1}$ assigned to links of ${\mathrm{SO}}_{4}^{2-}$ groups in the sulfated ${\mathrm{TiO}}_{2}$ samples. The observed ${\mathrm{N}}_{2}$ adsorption-desorption isotherms are typical of macro-mesoporous materials. For the non-sulfated ${\mathrm{TiO}}_{2}$ foam the surface area value (S) is equal to 50.37 ${\mathrm{m}}^{2}/\mathrm{g}$, while for sulfated samples S increases to 62.06 and to 79.96 ${\mathrm{m}}^{2}/\mathrm{g}$ as ${\mathrm{Ti}}^{4+}$:${\mathrm{SO}}_{4}^{2-}$ ratio increases from 0.1 to 1. The photodegradation reaction of methylene blue dye under UV radiation follows a first order mechanism; ${\mathrm{TiO}}_{2}$ sulfated samples exhibiting higher reaction constant rates than the non-sulfated ones.
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