Metallic iron for environmental remediation: Learning from electrocoagulation

Abstract

The interpretation of processes yielding aqueous contaminant removal in the presence of elemental iron (e.g. in Fe(0)/H(2)O systems) is subject to numerous complications. Reductive transformations by Fe(0) and its primary corrosion products (Fe(II) and H/H(2)) as well as adsorption onto and co-precipitation with secondary and tertiary iron corrosion products (iron hydroxides, oxyhydroxides, and mixed valence Fe(II)/Fe(III) green rusts) are considered the main removal mechanisms on a case-to-case basis. Recent progress involving adsorption and co-precipitation as fundamental contaminant removal mechanisms have faced a certain scepticism. This work shows that results from electrocoagulation (EC), using iron as sacrificial electrode, support the adsorption/co-precipitation concept. It is reiterated that despite a century of commercial use of EC, the scientific understanding of the complex chemical and physical processes involved is still incomplete.

Making Fe0-Based Filters a Universal Solution for Safe Drinking Water Provision

“…Noubactep and colleagues [199][200][201] have demonstrated that the dynamic nature of the process of in situ generation and precipitation of iron oxides implies that colloidal forms remove species without affinity to iron oxides to an unpredictable extent. For this reason, upon proper design, Fe 0 filters will be efficient at removing even very small species that would have needed high pressure (electricity) to be eliminated by reverse osmosis.…”

Factors affecting the Faradaic efficiency of Fe(0) electrocoagulation

“…In addition to single and binary anion electrolyte solutions, we also prepared a series of synthetic groundwater matrices (Table 2), which were designed to mimic a range of contaminated groundwaters that are candidates for Fe(0) EC field treatment [34][35][36][37][38]. For arsenic contaminated groundwater (pH 7.5), we prepared a synthetic Bangladesh groundwater (SBGW) electrolyte solution following a recipe derived from a British Geological Survey analysis of thousands of groundwater wells in Bangladesh [39].…”

Testing Metallic Iron Filtration Systems for Decentralized Water Treatment at Pilot Scale

“…Noubactep and Schöner [28] discussed the similarities between decontamination by electro-coagulation and by using granular metallic materials. According to Bojic et al [29], the great efficacy of voluminous insoluble Al(OH)3 for aqueous removal of many chemical and microbiological pollutants implies efficient water decontamination by a microalloyed aluminium based composite.…”