Photodegradation of methylene blue by in situ generated titania supported on a NaA zeolite

Abstract

The degradation of methylene blue dye was evaluated for a series of in situ generated titania resulting from the impregnation of TiCl4 into a series of NaA zeolites, which were synthesized using alternative silicon sources, namely rice husk and chrysotile, and submitted to different treatments. The resulting catalysts were characterized by X-ray diffraction spectrometry, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, diffuse reflectance and transmittance infrared Fourier transform spectroscopy, energy dispersive X-ray scanning electron microscopy and differential pulse voltammetry. The generated titania are present in the form of anatase phase, without alteration of the zeolite framework. Homogeneous distribution of Ti is reached for up to 10 wt.% Ti, where higher contents seem to afford isolated conglomerates. The highest catalyst activity was reached with samples having 10 wt.% Ti. Catalyst activity was shown to be comparable to that exhibited by commercial P-25 after 1 h of UV light exposition. Experiments carried out in natural sunlight reached 92% decomposition of the methylene blue dye.