FeOCl in Advanced Oxidization Processes for Water Purification: A Critical Review

Purpose of Review

Advanced oxidation processes (AOPs) are proven effective in degrading recalcitrant pollutants in wastewater. Numerous researchers have been targeting advanced catalytic materials to further promote AOP efficiency. Recent studies indicated the great catalytic activity of FeOCl in AOP systems, inducing the prevailing research on the modification and application of the FeOCl-based layer-structure materials. This review summarizes the progress in existing works of FeOCl as AOP catalysts and provides challenging perspectives for future work.

Recent Findings

FeOCl shows outstanding catalytic performance in conventional Fenton and other AOP systems, such as Fenton-like, photo-activated and electro-activated processes. Nevertheless, FeOCl catalytic efficiency in AOPs still demands improvement owing to the relatively low effective surface area of bulk-phase FeOCl, slow regeneration of active Fe (II) from Fe (III), prone leaching of iron ions, and difficulty in recycling or long-term functioning. Consequently, various modification approaches, including intercalation, exfoliation, combination, and membrane-fabrication, have been adopted to effectively promote pollutant removal efficiency in different FeOCl-catalyzed AOP systems.

Summary

This review presents the promising application of FeOCl as catalysts in AOPs and multiple modification methods successfully applied to FeOCl for catalytic performance improvement. Moreover, some remaining gaps in FeOCl preparation, purity determination, stability control, complex water matrix effects, and mechanism illustration are summarized, hopefully providing viable viewpoints for future research on AOP water treatment practices.

Graphical Abstract

Schematic illustration of FeOCl and its modified products in AOPs for water treatment.