Waste Heat-Activated Persulfate Degradation of Dye Wastewater

Due to its high-temperature nature, high-temperature dyeing wastewater is a major challenge for treatment. In this paper, using the high thermal energy of high-temperature printing and dyeing wastewater to activate persulfate (PS) for dye treatment was investigated. Acid orange 7 (AO7) was chosen as a model compound. The result shows that increasing the temperature or PS concentration is beneficial to AO7 degradation. Radical quenching tests suggest that the sulfate radical (SO₄^-) plays a dominant role in degradation process. Maximum AO7 degradation occurs at pH 7. Lowering or increasing pH results in a great decrease in AO7 degradation rates. The absorption spectra of remaining AO7 (PS/AO7 molar ratio of 100/1, 70°C) shows nearly non-absorption at ultraviolet zone. And the TOC removal at the same condition is 81.3%. Those results indicate that PS could not only decolorize AO7 but effectively mineralize it.