Enhanced photocatalysis in a pilot laminar falling film slurry reactor

Laminar falling film slurry (LFFS) photocatalytic reactors are one of the m ost efficient reactor configurations for conducting heterogeneous photocata lytic reactions, particularly for wastewater treatment. This paper presents a study on the oxidation of an aqueous salicylic acid waste in a pilot con tinuous flow LFFS photocatalytic reactor which has an optimum design for li ght absorption. In conducting the oxidation reaction, heterogeneous photoca talysis was supplemented with other photon-assisted processes. The effect o f light intensity, radiation wavelength, oxidizing-enhancing agents, substr ate and photocatalyst concentration, and exposure time were studied. A comp arison of six different photon-based processes showed that higher oxidation rates of salicylic acid were obtained when there was concomitant photocata lysis, photolysis, and UV peroxidation. The oxidation rates of salicylic ac id with this combined process were at least 1 order of magnitude higher in comparison with those for UVA photocatalysis and 3-fold higher in compariso n with homogeneous UVC photolysis/UVC peroxidation.