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- An improvement of photocatalytic activity of TiO2 Degussa P25 powderPublication . Bessergenev, V.; Mateus, M. C.; Botelho do Rego, A. M.; Hantusch, M.; Burkel, E.The photocatalytic activities of Degussa P25 powders annealed at various temperatures in vacuum and air were studied together with investigations of their compositions by XPS, of their crystal structures by XRD and of their specific surface areas by BET. It is shown that the photocatalytic activity of P25 powders was remarkably enhanced after vacuum annealing; the kinetic coefficient can be raised by 75% during annealing at 400 degrees C. It is obvious that this enhancement is not related to the adhesion ability of the P25 powders. (C) 2015 Elsevier B.V. All rights reserved.
- Photocatalytic reactor, CVD technology of its preparation and water purification from pharmaceutical drugs and agricultural pesticidesPublication . Bessergenev, V.; Mateus, Maria da Conceição; Morgado, I. M.; Hantusch, M.; Burkel, E.A tubular photocatalytic reactor of the immersion type for water purification from organic pollutants has been developed. Few important principles were used in the construction of the reactor, namely, a symmetrical and uniform light distribution with direct incidence of UV irradiation on the photocatalyst surface, a highly active mixing of contaminated water as a result of an air bubbling flux, that simultaneously supplying oxygen that is necessary for a photocatalytic reaction. The implemented highly active thin film photocatalyst was prepared by the Chemical Vapor Deposition (CVD) technology using titanium(isopropoxide) (TTIP) as a precursor. The factor K = Surface/Volume of this reactor is about 255 m(-1). Together with an effective mixing, it creates excellent contacts between the contaminants and the photocatalyst which is very favorable for water purification. The efficiency of this reactor was proven by the decomposition of some pharmaceutical drugs (Ibuprofen, Acetylsalicylic acid, Sulphanilamide, Paracetamol, Caffeine) and of some pesticides (Dimethoate, Azoxystrobin, Iprodione, Propizamid, Isoproturon, Fenarimol). The relation between the kinetic constants of photocatalysis and of photolysis is K-photcat/K-photolysis = 2 divided by 18. These results demonstrate the feasibility of the developed photoreactor for the degradation of recalcitrant organic pollutants, such as pharmaceuticals and pesticides in water. (C) 2016 Elsevier B.V. All rights reserved.