Rescuing Fe0 remediation research from its systemic flaws

Abstract

The well-accepted assumption of metallic iron (Fe 0 ) acting as electron donor for environmental remediation has created an unstable domain of knowledge for the past 23 years. This assumption is discouraging some outstanding and prospective scientists from correctly interpreting their experimental results. Such a situation is a recipe for long-term decline. The critical situation cannot be solved with simplistic approaches. It is now imperative to develop an understanding to defend the difficulties of this assumption and re-orient Fe 0 mediated remediation research as a whole.

The Impact of Selected Pretreatment Procedures on Iron Dissolution from Metallic Iron Specimens Used in Water Treatment

“…Disregarding any mechanistic discussions, the results in Table 2 rationalize the current "dialogue of the deaf" within the Fe 0 research community [109]. The way out of this confusing situation goes exclusively through systematic investigations [110,111].…”

“…This occurs because at pH > 4.5, the Fe 0 surface is constantly shielded by a universal oxide scale, acting as a diffusion barrier for any dissolved species [67][68][69][70][71][72]. Because the oxide scale is constantly present at the Fe 0 surface, the discussion of the mechanism of contaminant removal has been challenging [33,[55][56][57]72,111]. The results achieved herein contribute to clarify this dilemma because EDTA has no redox properties.…”

“…The long scientific history of using "Fe 0 for water treatment" demonstrates that the evidence that iron corrosion generates adsorbing species for decontamination was known before 1850 [2] and has been independently rediscovered several times thereafter [4,6,119,[121][122][123]. However, only in the context of subsurface reactive walls, Fe 0 was presented as its own reducing agent under environmental conditions, a possible mistake that is still difficult to address [55][56][57]109,111]. It is very interesting in this regard to note that, parallel to the discovery that Fe 0 may be a reducing agent [124], Khudenko [70,123] has presented cementation as a tool to induce the reductive transformation of organic contaminants.…”

“…Like electrocoagulation, the remediation Fe 0 /H 2 O system can be considered an enigmatic technology [136]. Despite having been industrially used for over 140 years, there appears to be no science-based rules on the appropriate approaches for the design of individual applications [33,55,102,103,111,137]. Accordingly, there is nothing like a path to the a priori modelling approach [86,87].…”

Metallic Iron (Fe0) Provide Possible Solution to Universal Safe Drinking Water Provision

“…Related investigations cleared up the nature of Fe 0 as coagulant-inducing agent both in the Bischof Process (packed-bed filtration) and in the Anderson Process (fluidized bed-like) [1,[4][5][6][7][8][9]. During the past three decades, sophisticated scientific methods have been used to produce a confused mass of discordant and mostly unfounded individual opinions [10][11][12] demonstrating that Fe 0 might be an environmental reducing agent [8,9,. This fact alone explains the absolute empiricism which thus far has dominated and still dominates research and field application of Fe 0 for environmental remediation and water treatment.…”