Metallic iron for environmental remediation: A review of reviews.

This article critically evaluates recent review articles on using metallic iron (Fe(0)) for environmental remediation in order to provide insight for more efficient Fe(0)-based systems. The presentation is limited to peer-reviewed articles published during 2014 and 2015, excluding own contributions, dealing mostly with granular Fe(0). A literature search was conducted up to June 15th 2015 using Science Direct, SCOPUS, Springer and Web of Science databases. The search yielded eight articles that met the final inclusion criteria. The evaluation clearly shows that seven articles provide a narrative description of processes occurring in the Fe(0)/H20 system according to the concept that Fe(0) is a reducing agent. Only one article clearly follows a different path, presenting Fe(0) as a generator of adsorbing (hydroxides, oxides) and reducing (Fe(II), H/H2) agents. The apparent discrepancies between the two schools are identified and extensively discussed based on the chemistry of the Fe(0)/H20 system. The results of this evaluation indicate clearly that research on 'Fe(0) for environmental remediation' is in its infancy. Despite the current paucity of reliable data for the design of efficient Fe(0)-based systems, this review demonstrates that sensible progress could be achieved within a short period of time, specific recommendations to help guide future research are suggested.