Photodegradation of naphthalene by non-stoichiometric titanium oxides – Magneli phases

Abstract

This work is concerned with photochemical degradation of naphthalene using non-stoichiometric titanium oxides Ebonex (Magneli phases). Ebonex was mechanically pretreated by milling in planetary mills for 20 h in order to reduce the particle size. For comparison, the photochemical degradation was performed by using of commercial photocatalyst TiO2 HOMBIKAT UV-100. Structural characterization of the photocatalysts was performed by means of XRD analysis, Raman spectroscopy and SEM microscopy. It was found that HOMBIKAT UV shows anatase crystalline structure with particle size of 10 nm. Ebonex contains mostly the first three non- stoichiometric oxides of the homologues series: Ti4O7, Ti5O9 and Ti6O11 with particle size of about 200 nm. The both photocatalysts form spherical micron- or submicron- scaled aggregates. Photochemical activity within the UV region of the light was deter- mined by means of FTIR spectroscopy. In both cases intensive activity was registered. However, Ebonex showed higher activity (the photocatalytic activity is more than 95%) related to the HOMBIKAT UV (the photocatalytic activity is near 60%). It is expected their photocatalytic activity to be more intensive in the visible region of the light.