Graphitized carbon encapsulated Co anode electrochemically activating persulfate for sulfamethoxazole degradation

The excessive use of antibiotics like sulfamethoxazole (SMX) is causing environmental pollution and endangering human health and the ecosystem. Using transition metals as catalysts to activate persulfate (PS) can effectively degrade the organic pollutants in the advanced oxidation process (AOP). However, the high dissolution of the transition metals leads to poor stability, low efficiency in pollutant degradation, and secondary pollution. In this work, a graphitized carbon encapsulated Co (Co@EC) anode is developed for electrochemically activating peroxymonosulfate (PMS) to degrade SMX. It is found that the synergistic effect of Co@EC, PMS, and current significantly enhances SMX degradation. Under optimal conditions (current density of 5 mA cm⁻², pH of 9, and PMS concentration of 0.25 mM), the Co@EC anode can completely remove 10 μM of SMX in 9 min, a much higher efficiency compared to processes without PMS, Co, or current. The rapid reaction kinetics (6.69×10⁻¹ min⁻¹) at optimal conditions are associated with the two main active species of ¹O₂ and O₂^•− during electroactivation. Furthermore, the Co@EC anode maintains high degradation efficiency and low dissolution after repeated cycling tests due to its structural stability. These findings provide new insights and strategies for developing stable catalysts.