Electro-enhanced degradation of atrazine via Co-Fe oxide modified graphite felt composite cathode for persulfate activation

Abstract

• FeO-CoFeO/GF was fabricated by in-situ solvothermal growth and calcination. • The sea urchin-like structure exhibited outstanding performance in PS activation. • The electric field significantly enhanced the transition metal cycle. • ATZ removal was mainly attributed to radical and non-radical oxidation. • Plausible degradation pathways and the toxicity during degradation were explored. The synergistic activation of persulfate (PS) by electrochemical oxidation (EO) and transition metals has gradually attracted attention as an emerging wastewater method. In this work, a Co-Fe oxide modified graphite felt composite cathode (FeO-CoFeO/GF) was prepared by in-situ solvothermal growth and calcination for PS activation to degrade atrazine (ATZ). The surface morphology, phase composition, microstructure, specific surface area, element valence, and electrochemical properties of the materials were characterized. The EO/FeO-CoFeO/GF + PS system achieved 100% ATZ removal within 35 min and PS was effectively activated by the electrically enhanced FeO-CoFeO/GF compared with other control experiments. The FeO-CoFeO/GF composite cathode exhibited superior catalytic activity in a wide pH range (3–9) and demonstrated good stability in six consecutive cycles. Reactive oxide species were identified by radical quenching tests and electron paramagnetic resonance. Electrochemical oxidation, radical oxidation and non-radical oxidation jointly participate in attacking ATZ. A catalytic mechanism for this synergistic system was proposed to explain PS activation and subsequent ATZ degradation. Furthermore, potential ATZ degradation pathways were proposed. Toxicity changes were evaluated using the Ecological Structure Activity Relationships and Escherichia coli growth inhibition tests. This work provides a feasible strategy for synergistically strengthening PS activation and promoting the degradation of persistent organic pollutants.