Abstract
In this work, the degradation of Acid blue 25 (AB25), an anthraquinonic dye and a widely used colorant in many industries, by photoactivated periodate (UV/IO4-) process was investigated. Experiments were conducted in batch mode using a low-pressure mercury lamp emitting mainly at 253.7 nm. The effects of the operational conditions such as periodate ions concentration, initial dye concentration, initial pH of the solution, and tert-butanol addition on the degradation of AB25 were examined. The results have shown that the degradation rate was increased in the presence of UV/IO4- 4 compared to UV irradiation alone. The degradation rate increased with the increase in periodate concentration to 1 mM and decreased slightly at higher values (> 1 mM). The degradation of AB25 decreased when the dye concentration increased. The extent of degradation was found to be inversely proportional to the initial concentration of dye. AB25 degradation was significantly affected by varying the initial solution pH. The fastest degradation was obtained at natural pH (6.4). The degradation of the dye was not appreciably affected by the addition of tert-butanol, known as an effective scavenger of center dot OH radicals, even at high concentration. Thus, the degradation of AB25 by photoactivated periodate technique was not dominated by an center dot OH pathway.