Revisiting Fenton Chemistry: From Classical Systems to Advanced Materials Design, Mechanisms, and Future Directions in Wastewater Treatment

The Fenton reaction remains one of the most widely investigated advanced oxidation processes for wastewater treatment due to its ability to generate highly reactive oxygen species capable of degrading persistent organic pollutants. However, classical homoge-neous Fenton systems suffer from significant limitations, including narrow pH applica-bility, iron sludge generation, and poor catalyst reusability. In response, extensive research has been devoted to the development of heterogeneous and advanced Fenton-like catalysts that address these challenges while improving catalytic efficiency and operational stabil-ity. This review provides a comprehensive analysis of the evolution of Fenton catalysis, from classical homogeneous systems to modern advanced materials, including nanostructured catalysts, carbon-based Fe–N–C systems, metal–organic frameworks, and single-atom catalysts. Particular emphasis is placed on key performance parameters such as catalytic activity, manufacturability, stability, and catalyst lifespan. A critical comparison of these systems highlights the trade-offs between activity, cost, and scalability, demonstrating that the most advanced catalysts do not necessarily offer the best practical performance. A dedicated life cycle assessment perspective is included, focusing on catalyst lifespan, reuse efficiency, and iron leaching, providing quantitative insights into long-term sus-tainability. The analysis reveals that while advanced catalysts significantly improve cu-mulative catalytic output, their environmental and economic viability depends on synthe-sis complexity and durability under realistic conditions. Finally, current challenges and future directions are discussed, including the need for scalable synthesis methods, improved mechanistic understanding, and integration into hybrid treatment systems. This review aims to bridge the gap between fundamental re-search and practical application, offering guidance for the design of next-generation sus-tainable Fenton catalysts for wastewater treatment.