Incorporation of photoactive TiO2 in an aluminosilicate inorganic polymer by ion exchange

Abstract

In the present paper, it is described a procedure to ion exchange in an aluminosilicate inorganic polymer (geopolymer) in order to incorporate photoactive TiO 2. Metakaolin base geopolymers synthesized at 40 and 90 °C were chosen to be ion-exchanged with a solutions of (NH 4) 2 TiO (C 2O 4) 2-H 2O with and without previous treatment with NH 4Cl. The final geopolymers were characterized by SEM, FT-IR, Raman, XRD, BET, UV/Vis spectroscopy and fluorescence. It was confirmed that ion-exchange method incorporated anatase TiO 2 particles inside the geopolymer, affecting the geopolymers bond vibration modes of the AlO 4-SiO 4 framework. The observed blue shift in the UV/Vis spectra, suggest that those TiO 2 nanoparticles grew inside the micropores of the geopolymer producing quantum size effects. The photoactivity of such particles was determined by means of photoluminescent spectra and bleaching of methylene blue (MB), which confirms the potential applications of ion-exchanged geopolymers (IEGs) for photocatalytic purposes. © 2011 Elsevier Inc. All rights reserved.