ENHANCED PHOTOCATALYTIC DEGRADATION OF PI-DONOR ORGANIC-COMPOUNDS BY N,N'-DIALKYL-4,4'-BIPYRIDINIUM-MODIFIED TIO2 PARTICLES

TiO2 powders (Degussa P-25) were modified by a bipyridinium V2+ monola yer. The resulting modified V2+-TiO2 photocatalyst reveals enhanced ac tivities for the light-induced degradation of the series of organic co mpounds, 1,4-dimethoxybenzene (1), 1,2-dimethoxybenzene (veratrole) (2 ), indole (3) and eosin (4), exhibiting electron donor properties. Pho todegradation of p-chlorobenzaldehyde (5) which lacks electron donor p roperties is inhibited in the presence of the modified photocatalyst V 2+-TiO2, whereas it degrades in the presence of unmodified TiO2. The e nhanced photodegradation of the series of electron-rich compounds is a ttributed to the formation of a supramolecular donor-acceptor complex with the bipyridinium units at the semiconductor surface. Concentratio n of the organic materials at the s.c. surface leads to effective util ization of photogenerated O-2(.-) and effective mineralization.