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Abstract
The further development of Fe(0)-based remediation technology depends on the profound
understanding of the mechanisms involved in the process of aqueous contaminant removal.
The view that adsorption and co-precipitation are the fundamental contaminant removal
mechanisms is currently facing a harsh scepticism. Results from electrochemical cementation
are used to bring new insights in the process of contaminant removal in Fe(0)/H(2)O
systems. The common feature of hydrometallurgical cementation and metal-based remediation
is the heterogeneous nature of the processes which inevitably occurs in the presence
of a surface scale. The major difference between both processes is that the surface
of remediation metals is covered by layers of own oxide(s) while the surface of the
reducing metal in covered by porous layers of the cemented metal. The porous cemented
metal is necessarily electronic conductive and favours further dissolution of the
reducing metal. For the remediation metal, neither a porous layer nor a conductive
layer could be warrant. Therefore, the continuation of the remediation process depends
on the long-term porosity of oxide scales on the metal surfaces. These considerations
rationalized the superiority of Fe(0) as remediation agent compared to thermodynamically
more favourable Al(0) and Zn(0). The validity of the adsorption/co-precipitation concept
is corroborated.
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