Magnetic copper smelter slag as heterogeneous catalyst for tetracycline degradation: Process variables, kinetics, and...

The treatment of solid wastes and wastewater for sustainable development has been a hot topic. This work proposes a novel process of "waste treating waste" using magnetic copper smelter slag (CSS) as heterogeneous catalyst. The effect of process variables and water matrix was studied on catalytic performance. Under conditions of CSS 10 g/L, H₂O₂ 100 mM, pH 4.4, and temperature 25 °C, tetracycline can be effectively degraded within 30 min. The apparent rate constant is comparable to or higher than previous reports, and the activation energy is 37 kJ/mol. The broad operation pH, slight effect of water matrix, and magnetic property of CSS are favorable for potential application. CSS was characterized by N₂ adsorption-desorption isotherm, SEM-EDS, XRD, XPS, ICP and zeta potential. The dominant components of CSS are fayalite and magnetite, and the major metals of Fe and Cu provide active sites for H₂O₂ activation. Hydroxyl radical generated by H₂O₂ activation is dominant oxidative specie for tetracycline degradation. The plausible mechanism of tetracycline degradation in the solution and on catalyst surface is proposed.