Photocatalytic thin film cascade reactor for treatment of organic compounds in wastewater

The photocatalytic oxidation of benzoic acid was investigated in a pilot sc ale-cascade photoreactor. The photoreactor consists of an array of UV lamps (40 W, 365 nm) illuminating a cascade of three inclined 316 stainless stee l plates, on which titanium dioxide (TiO2) was immobilized by electrophoret ic deposition. The percentage removal of total organic carbon (TOC) of liqu id samples was determined. The photocatalytic process was affected by sever al operating parameters. Increasing the solution temperature was found to r educe the dissolved oxygen (DO) level and to decrease the rate of the degra dation process. The Langmuir-Hinshelwood equation was found to be accurate for modeling the degradation of benzoic acid with initial concentrations of 50 ppm, 75 ppm and 100 ppm. The rate of removal of TOC was positively affe cted by UV light intensity, but appeared to be independent of solution flow rate in the range examined. Control experiments confirmed that the effects of adsorption of the solute onto the TiO2 catalysts and photolytic degradat ion were negligible.