Advances in heterogeneous iron nanocatalysts for enhanced Fenton-based processes in wastewater treatment

Heterogeneous nanostructured catalysts with unique structural and surface properties are indispensable for the optimal and efficient degradation of pollutants in wastewater remediation. In the present decade, iron nanocatalysts are primarily employed to efficiently degrade pollutants, such as organic dyes, pharmaceutical effluents and other emerging contaminants. Besides, they are found to possess surface, structural and functional elements at the nanoscale and remain intact and stable with effective supports, and thus, they operate under the degradation conditions involved in Fenton, Fenton-like, photo-Fenton and electro-Fenton processes. Their stability, structural entities, and distinct active sites make them suitable for such reactions in the environmental remediation process favouring sustainability. This review systematically inspects the recent advances in Fe-based nanocatalysts that enhance the Fenton reactions in wastewater treatment. The methodology, types of catalytic systems and mechanistic approaches are demonstrated to understand the efficacy and versatility of the nanocatalysts. Furthermore, the effects of the structure and morphology of metal nanostructures and the nature of support functionalities that control the coordination within the hybrid composites on the construction of heterogeneous interfaces are deliberated.