The release of untreated wastewater into aquatic sources is impacting the quality of drinking water. It is estimated that about 20% of the pollutants are dyes that are not properly treated before being discharged into the wastewater streams. These dyes may undergo further reduction under anaerobic condition and form several toxic compounds that also possess threat to the water ecosystem. In this regard, Advanced Oxidation Processes (AOPs) such as heterogeneous photocatalysis is considered as an effective method for removal of organics from the water sources. Several metal and mixed metal oxides have been utilized for the removal of pollutants. Among them, mixed oxide materials, such as titania-silica and titania-alumina have been widely used for degradation of pollutants due to their enhanced surface properties. In this study, a set of titania-alumina (TiO2-Al2O3) mixed oxide materials were prepared by a modified sol-gel synthesis route, and the gels were dried using supercritical carbon dioxide. The supercritical drying process minimizes the pore collapse via removing the solvent in a fluid state, and, thus, the porosity of the materials are in general relatively higher. The synthesized materials were extensively characterized using several techniques that include powder X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XPS studies indicate the existence of Al-O-Al, Al-O-OH, Ti-O-Ti, and Ti-O-OH in TiO2-Al2O3 mixed oxides. The degradation of the dye rhodamine B (RhB) was confirmed by the identification of several fragments of RhB with different m/z values from the Liquid Chromatogram - Mass Spectroscopic (LC-MS) studies. Our results suggest that Al-O-OH bond on the surface of the mixed oxide materials could possibly have an impact whereas the particle size of the photoactive species, titania, is the key factor for effective degradation of the dye.

Implication of particle size of titania on degradation of rhodamine B over TiO2-Al2O3 mixed oxide materials

251st National Meeting (2016)

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