Recent advance of Fe-based bimetallic persulfate activation catalysts for antibiotics removal: Performance, mechanism, contribution of the key ROSs and degradation pathways

Antibiotic residues have been widely discovered in different types of water bodies, posing a critical risk to the water ecosystem and human health. Persulfate activation based advanced oxidation process (AOP), as an actual hot research topic for the removal of antibiotic contaminants from water has shown advantages of strong oxidation, high selectivity and wide pH applicability range. Iron-based heterogeneous activators have become the most popular transition metal materials in this persulfate-based AOP due to their versatility, flexibility, efficiency and environmental friendliness. Low-cost, highly stable and catalytically excellent iron-based bimetallic catalysts could activate persulfate exceptionally, which sorted out the vulnerability of single Fe activators to deactivation, low efficiency and susceptibility to secondary contamination. This article reviewed the characteristics and research progress of spinel ferrites, Fe-containing layered double hydroxides, Fe-based bimetallic metal–organic frameworks, Fe-based perovskites, Fe-containing bimetallic oxide complexes and other Fe-based bimetallic catalysts, evaluated their strengths and weaknesses and summarized the commonly used modification methods. Besides a systematic discussion on the intrinsic mechanisms driving the process of persulfate activation with iron-based bimetallic catalysts, it is for the first time that the workflows of qualitative analysis of reactive oxygen species (ROSs) and two calculation models for quantitative determination of their contribution rates have been thoroughly organized. The commonly degradation pathways and toxicity analysis of six types of antibiotics were summarized. Finally, research progress in engineering design of materials is also generalized. It is expected to provide clear ideas for future research about the development and application of Fe-based bimetallic catalysts, the corresponding modifications, derivatives and complexes in the activated persulfate process and to improve the reasoning of the degradation mechanism of this system.