Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Over the past 30 years the literature has burgeoned with in situ approaches for groundwater remediation. Of the methods currently available, the use of metallic iron (Fe<jats:sup>0</jats:sup>) in permeable reactive barrier (PRB) systems is one of the most commonly applied. Despite such interest, an increasing amount of experimental and field observations have reported inconsistent Fe<jats:sup>0</jats:sup> barrier operation compared to contemporary theory. In the current work, a critical review of the physical chemistry of aqueous Fe<jats:sup>0</jats:sup> corrosion in porous media is presented. Subsequent implications for the design of Fe<jats:sup>0</jats:sup> filtration systems are modeled. The results suggest that: (i) for the pH range of natural waters (>4.5), the high volumetric expansion of Fe<jats:sup>0</jats:sup> during oxidation and precipitation dictates that Fe<jats:sup>0</jats:sup> should be mixed with a non‐expansive material; (ii) naturally occurring solute precipitates have a negligible impact on permeability loss compared to Fe<jats:sup>0</jats:sup> expansive corrosion; and (iii) the proliferation of H<jats:sub>2</jats:sub> metabolizing bacteria may contribute to alleviate permeability loss. As a consequence, it is suggested that more emphasis must be placed on future work with regard to considering the Fe<jats:sup>0</jats:sup> PRB system as a physical (size‐exclusion) water filter device.</jats:p>