Investigating the Fe0/H2O systems using the methylene blue method: Validity, applications, and future directions

Konadu-Amoah, Bernard; Ndé-Tchoupé, Arnaud Igor; Hu, Rui; Gwenzi, Willis; Noubactep, Chicgoua

doi:10.1016/j.chemosphere.2021.132913

Cited by 17 publications

(19 citation statements)

References 141 publications

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“…While in this research, the effects were observed in 15 and 30 g/L dosages. According to Konadu-Amoah [56], the addition of Fe 0 materials into the polluted water lead to a generation of iron corrosion products (FeCPs) that mediate contaminants removal. However, excessive precipitating FeCPs (Equation (3)) due to higher Fe 0 materials doses may enmesh, adsorb and or inactivate some microorganisms responsible for the digestion of the pollutants [56][57][58].…”

Section: Codmentioning

confidence: 99%

“…According to Konadu-Amoah [56], the addition of Fe 0 materials into the polluted water lead to a generation of iron corrosion products (FeCPs) that mediate contaminants removal. However, excessive precipitating FeCPs (Equation (3)) due to higher Fe 0 materials doses may enmesh, adsorb and or inactivate some microorganisms responsible for the digestion of the pollutants [56][57][58]. Although the increased Fe 0 materials mass loading is required for producing enough H 2 for the microbial respiration (Equation ( 2)) [13,20,48] but too large doses should be avoided for contra-productivity, as shown here (Figure 3a and Table 3) and elsewhere [12,18].…”

Section: Codmentioning

confidence: 99%

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Fe0-Supported Anaerobic Digestion for Organics and Nutrients Removal from Domestic Sewage

Bakari

Njau

Noubactep

2022

Water

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Results from different research suggest that metallic iron (Fe0) materials enhance anaerobic digestion (AD) systems to remove organics (chemical oxygen demand (COD)), phosphorus and nitrogen from polluted water. However, the available results are difficult to compare because they are derived from different experimental conditions. This research characterises the effects of Fe0 type and dosage in AD systems to simultaneously remove COD and nutrients (orthophosphate (PO43−), ammonium (NH4+), and nitrate (NO3− Lab-scale reactors containing domestic sewage (DS) were fed with various Fe0 dosages (0 to 30 g/L). Batch AD experiments were operated at 37 ± 0.5 °C for 76 days; the initial pH value was 7.5. Scrap iron (SI) and steel wool (SW) were used as Fe0 sources. Results show that: (i) SW performed better than SI on COD and PO43− removal (ii) optimum dosage for the organics and nutrients removal was 10 g/L SI (iii) (NO3− + NH4+) was the least removed pollutant (iv) maximum observed COD, PO43− and NO3− + NH4+ removal efficiencies were 88.0%, 98.0% and 40.0% for 10 g/L SI, 88.2%, 99.9%, 25.1% for 10 g/L SW, and 68.9%, 7.3% and 0.7% for the reference system. Fe0-supported AD significantly removed the organics and nutrients from DS.

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Section: Codmentioning

confidence: 99%

Section: Codmentioning

confidence: 99%

Fe0-Supported Anaerobic Digestion for Organics and Nutrients Removal from Domestic Sewage

Bakari

Njau

Noubactep

2022

Water

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“…This is currently not the case as even "critical" reviews are written without any hint on the controversy existing in the literature with respect to the mechanisms of contaminants removal in Fe 0 /H 2 O systems (Noubactep 2014;Thakur et al 2020). This communication is not addressing the related controversies; interested readers are referred to the following five representative articles: Gheju and Balcu (2011), Ghauch (2015), Noubactep (2014), Hu et al (2021b), andKonadu-Amoah et al (2022).…”

Section: The Science Of the Fe 0 /H 2 O Systemmentioning

confidence: 99%

“…Because only some two or three research groups had adopted quiescent conditions, results are not really comparable to other published data and no profound discussion was possible. A key aspect was the development of the methylene blue method (MB method) which is the sole available tool to characterize the dynamics within the Fe 0 /H 2 O system without relying on a specific contaminant (Btatkeu-K et al 2016;Konadu-Amoah et al 2022). The MB method assesses the availability of iron corrosion products (FeCPs), or the extent of iron corrosion as influenced by selected operational parameters.…”

mentioning

confidence: 99%

“…For example, for column studies, the time to contaminant breakthrough has never been a key evaluation parameter. Rather, systems were designed for rapid breakthrough such that their behavior after breakthrough can be characterized for the longest experimental duration (Miyajima and Noubactep 2013;Konadu-Amoah et al 2022). Before 2007, tools to characterize the Fe 0 intrinsic reactivity were already presented as summarized in one of the papers (Btatkeu-K et al 2016).…”

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confidence: 99%

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Realizing the potential of metallic iron for the mitigation of toxics: flee or adapt?

Konadu-Amoah

Cao

et al. 2022

Appl Water Sci

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Metallic iron (Fe0) has been increasingly used to remove toxics from water over the past three decades. However, the idea that metallic iron (Fe0) is not an environmental reducing agent has been vigorously refuted. Researchers presenting their findings in a scientific journal have to accept the burden of proving that their argument has any validity. This 30-year-lasting discussion within the Fe0 remediation community is alien to electro-chemists, as it is a century-old knowledge. Nevertheless, the peer-reviewed literature on “remediation using Fe0” seems to be dominated by evaluators thinking that Fe0 is a reducing agent. This communication challenges the view that Fe0 donates any electron to any dissolved species. The sole goal is to reconcile a proven efficient technology with its scientific roots and enable the design of better Fe0 remediation systems.

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Materials for sustainable metallic iron-based water filters: a review

Xiao,

Hu,

Gwenzi

et al. 2024

Environ Chem Lett

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Water pollution is calling for a sustainable remediation method such as the use of metallic iron (Fe0) to reduce and filter some pollutants, yet the reactivity and hydraulic conductivity of iron filters decline over time under field conditions. Here we review iron filters with focus on metallic corrosion in porous media, flaws in designing iron filters, next-generation filters and perspectives such as safe drinking water supply, iron for anaemia control and coping with a reactive material. We argue that assumptions sustaining the design of current Fe0 filters are not valid because proposed solutions address the issues of declining iron reactivity and hydraulic conductivity separately. Alternatively, a recent approach suggest that each individual Fe0 atom corroding within a filter contributes to both reactivity and permeability loss. This approach applies well to alternative iron materials such as bimetallics, composites, hybrid aggregates, e.g. Fe0/sand, and nano-Fe0. Characterizing the intrinsic reactivity of individual Fe0 materials is a prerequisite to designing sustainable filters. Indeed, Fe0 ratio, Fe0 type, Fe0 shape, initial porosity, e.g. pore size and pore size distribution, and nature and size of admixing aggregates, e.g. pumice, pyrite and sand, are interrelated parameters which all influence the generation and accumulation of iron corrosion products. Fe0 should be characterized in long-term experiments, e.g. 12 months or longer, for Fe dissolution, H2 generation and removal of contaminants in three media, i.e., tap water, spring water and saline water, to allow reactivity comparison and designing field-scale filters.

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Investigating the Fe0/H2O systems using the methylene blue method: Validity, applications, and future directions

Cited by 17 publications

References 141 publications

Fe0-Supported Anaerobic Digestion for Organics and Nutrients Removal from Domestic Sewage

Fe0-Supported Anaerobic Digestion for Organics and Nutrients Removal from Domestic Sewage

Realizing the potential of metallic iron for the mitigation of toxics: flee or adapt?

Materials for sustainable metallic iron-based water filters: a review

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