Metallic iron for environmental remediation: learning from electrocoagulation.
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.
Angewandte Geologie, Universität Göttingen, Goldschmidtstrasse 3, D-37077 Göttingen, Germany. cnoubac@gwdg.de
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D000327:Adsorption; D004563:Electrochemistry / Q000379:methods; D004564:Electrocoagulation / Q000379:methods*; D004566:Electrodes; D052918:Environmental Restoration and Remediation; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods
D008670:Metals; D010087:Oxides; D014874:Water Pollutants, Chemical; D014867:Water; D007501:Iron