PHOTOCATALYTIC DECOMPOSITION OF 2,3-DICHLOROPYRIDINE OVER AQUEOUS SUSPENSIONS OF TIO2

The photocatalytic degradation of various dichloropyridines, with spec ial attention to 2,3-dichloropyridine (2,3-DCPy), has been investigate d in aqueous heterogeneous solutions containing TiO2 as photocatalyst. The disappearance of the organic molecule follows approximately a pse udo-first kinetic order according to the Langmuir-Hinselwood model. Th e apparent rate constant appeared to decrease with the initial concent ration of the DCPy. The decomposition rates of the various DCPy's, as well as the CO2 formation, were found to be about the same, regardless of the position of the chlorine atoms in the ring. As mineralization products CO2 and Cl- ions have been identified, whereas the nitrogen a tom forms only NH4+ ions. Various commercial photocatalysts were compa red with respect to their overall efficiency, as well as the productio n of CO2.