Loss of scientific integrity in using metallic iron (Fe0) for water remediation: Letʼs agree to disagree

This is the authors' abstract. We don't add key points for this paper.

• Metallic iron (Fe0) is an excellent reactive material for water remediation in filters. • Fe0 generates iron oxides and hydroxides (FeCPs) that are contaminant scavengers. • In Fe0/H2O systems, contaminants are reduced by secondary corrosion products. • Only hybrid Fe0 systems comprising non expansive aggregates can be sustainable. • To date, little attention has been paid to the non-linear kinetics of Fe° corrosion. Metallic iron (Fe 0 ) seems to be a well-acknowledged reactive material for water treatment at several scales. Many operating systems have been designed based on the premise that Fe 0 is a reducing agent, transforming reducible species (E 0 > –0.44 V) under environmental conditions (electrochemical reaction – electrons from Fe 0 ). However, Fe 0 -remediation systems developed from this starting point are not optimally suited for harnessing their full potential. In contrast, the alternative approach regarding Fe 0 as a generator of contaminant scavengers (e.g. iron oxides) and reductive species (e.g. Fe II , H 2 ) can allow for the tailored development of innovative systems capable of achieving various treatment objectives, including contaminant reduction through an indirect mechanism (e.g. electrons from Fe II , Fe 3 O 4 , H 2 ). This perspective article comparatively analyzes the two distinct approaches for the Fe 0 -based water remediation technology. Results show that the alternative pathway facilitates the design of Fe 0 -remediation systems to accommodate different Fe 0 -driven treatment processes, while potentially accomplishing enhanced treatment efficiency, at reduced costs. The resulting science-based systems have the potential to drive technological revolution in water treatment for achieving water security worldwide.