Tailored anthraquinone-based covalent organic frameworks boosted atrazine degradation through peroxymonosulfate activation driven by visible light

Abstract

Atrazine (ATZ), a wildly used s-triazine herbicide to avoid grassy insects and weeds, causes biological and environmental issues due to its prolonged existence and various toxic properties. Peroxymonosulfate (PMS) photoactivation-based advanced oxidation processes (AOPs) meet the challenges of sustainable energy and environmental concerns, and thus are promising challenging for ATZ degradation. However, preparing photocatalysts to realize efficient ATZ degradation remains challenging. Here, we prepared the highly efficient visible-light photocatalyst with abundant anthraquinone groups, i.e. TpDQ-COF, which was employed to activate PMS for fast and efficient ATZ degradation. ATZ degradation in the TpDQ-COF/PMS system reached 0.127 min⁻¹ under visible light (VL), which is ca. 17.9 times that of TpDA-COF without anthraquinone. It implies that anthraquinone units served as pivotal active sites for facilitating photoelectron separation and migration, which triggered ROS generation towards highly effective ATZ degradation. In addition, the radical-quenching and Electron Paramagnetic Resonance (EPR) experiments proved that ^•OH, ^•SO₄^- and ¹O₂ played pivotal roles in ATZ degradation under TpDQ-COF/PMS/VL system. The ATZ degradation pathways included dealkylation, dechlorination-hydroxylation, alkylic-hydroxylation, and alkylic-oxidation, which were confirmed by intermediates and density functional theory (DFT) analysis. Overall, TpDQ-COF showcased its excellent practical utility in the removal of organic pollutants in contaminated water.