Heterogeneous activation of peroxygens by iron-based bimetallic nanostructures for the efficient remediation of contaminated water. A review

Heterogeneous advanced oxidation processes (AOPs) catalyzed by iron-based bimetallic nanoparticles were discovered efficient for water remediation due to the formation of a variety of reactive species, such as sulfate radical, hydroxyl radical, superoxide radical, and nonradical oxidation routes. The addition of reducing agents or the incorporation of a second metal accelerated the Fe (III)/Fe (II) redox cycle, allowing for the in-situ formation of H2O2 (a precursor to center dot OH). The activated peroxymonosulfate (PMS) system oxidized contaminants faster than the activated peroxydisulfate (PS) and H2O2 systems. Besides, iron-based bimetallic catalysts demonstrated potent antimicrobial activity and toxic heavy metals removal from contaminated water. This review summarizes the recent advances in synthesis methods, activation of peroxygens, and degradation mechanisms via bimetallic iron, iron-based bimetallic oxide, iron-based metal-organic frameworks, chalcopyrite, and iron-based perovskites. Additionally, the effects of various water constituents and parameters (stoichiometric ratio, catalyst concentration, oxidant dosage, pH, anions, and natural organic matter) are discussed. It is anticipated to broaden our understanding of the activation mechanisms, removal efficiency, and stability of iron-based catalysts and transformation pathways.