Photocatalytic decomposition of 2,3‐dichloropyridine over aqueous suspensions of TiO2

Abstract
The photocatalytic degradation of various dichloropyridines, with special attention to 2,3‐dichloropyridine (2,3‐DCPy), has been investigated in aqueous heterogeneous solutions containing TiO2 as photocatalyst. The disappearance of the organic molecule follows approximately a pseudo‐first kinetic order according to the Langmuir‐Hinselwood model. The apparent rate constant appeared to decrease with the initial concentration 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 atom forms only NH4 + ions. Various commercial photocatalysts were compared with respect to their overall efficiency, as well as the production of CO2.