Influence of synthesis conditions on TiO2 composition and photocatalytic activity employing microwave assisted hydrothermal method

Reference	Presenter	Authors (Institution)	Abstract
06-205	Ana Rita Ferreira Alves Teixeira	Teixeira, A.F.(Universidade Federal da Paraíba); Pontes, L.F.(Universidade Federal da Paraíba); Santos, I.M.(Universidade Federal da Paraíba);	Titanium dioxide is a widely studied material with well-known applications for anatase and rutile phases. Recently, brookite, another polymorph which is more difficult to obtain, has caught scientific community interest as a promising material for photocatalysis. Among synthesis methodologies, hydrothermal method stands out due to the possibility of phase composition control by variation of synthesis parameters, while the use of a microwave-assisted heating decreases reaction time [1,2]. In this sense, this work aimed at evaluating the influence of synthesis conditions on phase composition and photocatalytic activity of TiO2 samples. Titanium isopropoxide was hydrothermally treated in water/isopropanol media, after addition of different sodium salts and pH adjustment. Reactions were carried out both in a microwave and in an electric oven, for comparison. The samples obtained were characterized by XRD, FTIR, UV-Vis. TiO2 samples were obtained and the anatase:brookite ratios were estimated from the main XRD peaks employing methodology previously described [3]. After hydrothermal treatment, some samples were submitted to heat treatment between 873 and 1273 K and transition to titanate structure was observed. Samples obtained employing NaNO3 as sodium salt showed brookite content ranging between 10% and 35%, but no change on the band gap values was observed, which was 3.1 eV. The photocatalytic activity of the materials was evaluated for decolorization of remazol golden yellow (RNL) dye aqueous solutions. The photocatalytic tests were carried out with a 10 mg.L-1 RNL solution under stirring and UV irradiation. After 4 h, the sample containing 10% of brookite reached 58% decolorization, while one sample with 30% of brookite reached 80% decolorization. [1] F. Dufour et al. Eur. J. Inorg. Chem, 2012, 2707 [2] S. Kumar; K. Rao. Nanoscale, 2014, 6, 11574 [3] H. Zhang; J. Banfield. J. Phys chem B, 2000, 104, 3481 This work was supported by PROINFRA/FINEP/MCTIC, Capes/MEC
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