Critical analysis of the role of various iron-based heterogeneous catalysts for advanced oxidation processes: A state of the art review

Removal of recalcitrant organic pollutants via advance oxidation process (AOP) is an effective and green approach in the field of wastewater treatment. Fenton process is one such kind of AOP technique that employs iron (Fe) materials and oxidizing agent to attain degradation of organic pollutants though the generation of reactive organic species (ROS). In this review, the utility of natural and synthetic iron materialstowards water remediation process has been discussed in detail in relation to Fenton chemistry. The geochemistry of natural iron materials (oxides and sulfides) and chemistry of synthetic iron materials (nanomaterials and their impregnated forms) has been discussed to understand their role in Fenton processes. Additionally, the emergence of ferrates as a new and promising candidate for the removal of organic pollutants has been highlighted. A detailed investigation on the effect of various operational parameters such as pH, catalyst dose, foreign ion, oxidant concentration, and chelating agents in affecting the performance of iron materials has been highlighted. A summary on the potency of various iron materialstowards removing diverse kind of organic compounds from aqueous medium has been provided. At last, the review has been concluded with emphasizing the drawbacks and benefits of using Fe material for realizing Fenton and Fenton-like processes.