Tris–Co(II)–H(2)O(2) System-Mediated Durative Hydroxyl Radical Generation for Efficient Anionic Azo Dye Degradation by Integrating Electrostatic Attraction

[Image: see text] The development of simple Fenton/Fenton-like systems with durative hydroxyl radical ((•)OH) generation characteristics is significant to rapid organic pollutant degradation and cost-effective water treatment. In this study, a tris(hydroxymethyl)aminomethane (Tris)-incorporated Co(II)–H(2)O(2) Fenton-like system has been successfully constructed for efficient Sunset Yellow (SY, a typical anionic azo dye) degradation under alkaline conditions. The mechanism of the enhanced degradation consists of two parts: first, the Tris–Co(II) complex triggers the durative generation of highly oxidized hydroxyl radicals; second, electrostatic attraction between SY and the Tris–Co(II) complex shortens the radical–SY interaction time and facilitates the degradation of SY. With the introduction of Tris to this proposed system, the decolorization rate of SY can be increased from 37.0 to 98.0% after 50 min and efficient SY degradation with a high total organic carbon removal efficiency (>59.0%) is achieved under a wide initial pH from 8.7 to 12.0. Moreover, the universality of the designed system for anionic azo dye degradation is verified with reactive red and congo red.