Probing the extent of [O2] depletion and [Cl-] production simultaneously at an illuminated TiO2 surface employing simple electrochemical methods

The extent Of [O-2] disappearance and Cl- production simultaneously from the UV-sensitised photodegradation of an aqueous aerated 4-chlorophenol (4-CP) solution at TiO2 surface have been investigated electrochemically, employing an oxygen sensor probe and a Ag/AgCl potentiometric detector electrode, respectively. The preceding mineralisation of 4-CP was monitored potentiometrically in terms of Cl- formation with illumination time while O-2 electrode allowed the direct measurement of any change in [O-2] at the illuminated TiO2 surface. A direct correlation was observed between the rates Of O-2 consumption and Cl- formation in the ongoing photo-process, which provided information that the photomineralisation process is ultimately an electrochemical process, in which the anodic (hole consumption) and cathodic (electron consumption) rate must balance. (C) 2003 Elsevier Science B.V. All rights reserved.