Sulfate radicals-based degradation of antraquinone textile dye in a plug flow photoreactor

The study evaluated the degradation of the antraquinone textile dye reactive blue 19, a frequently used dye in the textile industry, by means of sulfate radicals. Sulfate radicals were generated by activation of peroxydisulfate with UV-C (254 nm) irradiation. UV irradiation alone did not affect the removal efficiency, while with the addition of an oxidant, the removal efficiency was significantly improved. The degradation rates of the textile dye increased at higher initial dosages of oxidant, while the opposite trend was observed in the case of increasing initial dye concentration. Acidic conditions were more convenient for degradation of the dye then neutral or basic. Degradation of the textile dye was not affected by the presence of bicarbonate and chloride anions within the concentrations range from 1 to 200 mmol?L-1. The presence of carbonate showed a suppressing effect on the removal efficiency, especially at carbonate levels below 20 mmol?L-1. However, at carbonate levels greater than 20 mmol?L-1, the dye removal efficiency increased. The use of methanol and tert-butanol as scavengers revealed that both radicals, HO?and SO4?-, would be generated depending on initial pH value of the dye solution.