Advanced oxidation of 4-chlorobenzaldehyde in water by UV-light, ozonation and combination of both methods

A comparative study was performed on the oxidizing degradation of 4-CLBzAl (used a model pollutant in water) by photolysis (lambda=253.7 nm), ozonation and by combination of both methods. The resulting yields of the degradation products (Cl- ions, aldehydes, carboxylic acids) were investigated as a function of UV-dose and action of ozone. The product yields were determined by HPLC-analysis and their initial quantum yields (Q(i)) were calculated. Based on the results, it was shown that the synergistic action of UV-irradiation and ozone leads to a more efficient degradation of 4-CLBzAl. For explanation of the experimental results probable reaction mechanisms are suggested. (C) 1998 Elsevier Science Ltd.