SINGLE-ATOM IRON CATALYSTS FOR PERSULFATE ACTIVATION AND SELECTIVE DESTRUCTION OF PERSISTENT ORGANIC CONTAMINANTS IN WASTEWATER

Abstract

The unrelenting contamination of global water resources with recalcitrant organic pollutants such as pharmaceuticals, endocrine-disrupting chemicals (EDCs), and other industrial micropollutants presents formidable ecological and public health threats beyond the purview of conventional wastewater treatment technologies. Recently developed advanced oxidation processes (AOPs) utilizing persulfate (PMS) activation represent a promising route forward. However, traditional approaches using homogenous/heterogeneous catalysts face limitations including metal sludge formation, constrained operating pH window, and limited atom utilization efficiency. Single-atom iron catalysts (SA-Fe) incorporating Fe active sites coordinated to N-rich carbon matrix (Fe-N-C) have proven remarkably effective at enabling near complete PMS utilization via novel reaction mechanisms favoring selective, non-radical pathways involving high-valent Fe-oxo species (Feᴵⱴ=O) and singlet O2 (¹O2). This perspective reviews the synthesis methodologies, design principles, and microenvironment coordination engineering of state-of-the-art SA-Fe catalysts. Emphasis is placed on their mechanistic deployment through advanced spectroscopic investigations in persulfate activation processes, alongside evaluation of system-level performance advantages in varied conditions spanning diverse pH regimes (3.0-11.0), real-world contaminant mixtures, and challenging aqueous media comprising background inorganic anions and natural organic matter (NOM). Representative pollutant fate trajectories of model sulfonamide antibiotic (sulfamethoxazole), tetracycline antibiotic and bisphenol A are discussed in detail regarding kinetic behaviors, mineralization routes, and detoxification efficiencies achieved via SA-Fe/PMS protocols. Critical barriers impeding further development including scalable synthesis strategies, operando characterization techniques, and reactor integration schemes are addressed along with prospective research avenues towards successful translation to real world environmental remediation applications.