The advanced oxidation processes based on sulfate radicals offer environmental sustainability and exhibit potential for effectively breaking down antibiotics. Among various iron-based materials for activating peroxydisulfate, copper slags are iron-rich raw material and can serve as an excellent catalyst. In this study, acid-activated copper slag-based geopolymers were successfully synthesized using a 1:1 mass ratio of copper slag and metakaolin as raw materials. In the geopolymer based electrocatalytic system, the removal of sulfamethoxazole (SMX) was 99.1 % within 60 mins under the optimized operating conditon of initial pH 3.0, current density of 20 mA/cm2, inter-electrode distance of 3 cm, geopolymer dosage of 1 g/L, and electrolytic concentration of 75 mM/L. The presence of GP provided surface Fe(II) to further activate H2O2 and peroxydisulfate and hence promote the degradation of SMX. Electron paramagnetic resonance spectroscopy, quenching experiments, electrochemical techniques, and probe analysis, were employed to investigate the radical and nonradical pathways within the system. The reactive oxygen species identified in the proposed system included hydroxyl radicals (·OH), sulfate radicals (SO4·-), and singlet oxygen (1O2). SO4·- was the predominant reactive oxygen species, playing a crucial role in the radical pathway with a contribution of 62.1 %. 1O2 was the sole nonradical pathways involved, exerting limit influence on SMX degradation. Additionally, six potential intermediate pathways for SMX degradation were identified. This research not only systematically offers a comprehensive understanding of the oxidation mechanisms in heterogeneous electro-catalytic systems but also demonstrates a high-value utilization strategy of metallurgical industrial solid waste for resource recycling.