DEGRADATION OF COMMERCIAL AZO DYES IN WATER USING OZONATION AND UV ENHANCED OZONATION PROCESS

The chemical oxidation of eight non-biodegradable azo dyes by ozonatio n and photooxidation process was studied in a pilot scale photochemica l (UV/ozone) reactor. In experiments with ozone bubbling, the degradat ion of eight azo dyes was found to occur in the absence of UV light. T he degradation rate of azo dyes was observed to be first order with re spected to both azo dye and ozone concentrations. The pH of the soluti on decreased while the azo dyes degraded. UV light did not significant ly enhance the degradation ability of the ozonation reaction under var ious conditions. No degradation was observed when the azo dye solution was irradiated by UV light alone. Effects of ozone dosage, and initia l concentrations of azo dyes are discussed. Time for removal of 50% of azo dye and rate constants can be used to determine the decomposition rate of each azo dye by different oxidation processes as a function o f various conditions.