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Preparation, characterization and testing of a bulky non-supported photocatalyst for water pollution abatement

Abstract:

An innovative bulky photocatalyst for water decontamination has been developed. The semiconductor (TiO2) is homogeneously distributed in an aggregating material through the whole piece. This design prevents the activity reduction usually observed in supported catalysts due to the loss of the photoactive layer, and facilitates its recovery for an easy reuse, which is a recurrent problem dealing with nanoparticles. The photocatalyst combines the excellent properties of TiO2 with those of a natural clay, which serves as binder, slows down the phase transition of anatase to rutile upon calcination, and has a synergetic function. The photocatalyst has been prepared in the form of small pellets with an Ecuadorian clay and TiO2 in the commercial form of P25 by evenly dry mixing, forming a paste with water, and subsequent extrusion, drying and calcination at 600 °C. The photodegradation of phenol, as a model pollutant, has been achieved by using this aggregate material in a flow reactor with artificial UVA-Vis radiation, and reused without any significant loss of activity. The photocatalyst showed an optimum activity at a 40% clay / 60% P25 ratio, while higher calcination temperatures had a negative effect on its performance.