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Cited by 14Advanced oxidation water treatmentWater Treatment and DisinfectionEnvironmental and Analytical Chemistry Studies

The DOI matches its Crossref record; 17 of the 17 references it cites were found in a registry or an index; 1 of the 31 sources its claims cite were checked for support.

Analytical quantification of electrochemical ferrates for drinking water treatments

Open access
Cataldo Hernández, Macarena A., May, Andrew, Bonakdapour, Arman, Mohseni, Madjid, Wilkinson, David P.·2017·Canadian Journal of Chemistry
DOI 10.1139/cjc-2016-0315
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Abstract

Ferrate ions are a highly oxidizing and unstable species that are challenging to quantify and analyze. They are, however, becoming increasingly recognized as an excellent candidate for a number of applications such as for water treatment. A wider acceptance of ferrates requires an accurate assay of the produced ferrates. We report on four analytical methods (existing and new) for quantification of ferrates and discuss their advantages and disadvantages. These methods include titrimetric analysis and spectrometric techniques such as direct colorimetric measurements of ABTS or NaI colorimetric. In terms of accuracy, the cost, simplicity, and time required the modified indirect UV-Vis NaI method is shown to be the most effective of all of the four methods investigated.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper evaluates four analytical methods for quantifying electrochemically generated ferrate for drinking water treatment and modifies them for high-pH, low-concentration solutions. It concludes that the modified indirect UV-Vis/NaI method is the most effective overall in accuracy, cost, simplicity, and time.

Key findings

  • The modified indirect UV-Vis/NaI method was the most effective of the four methods investigated, being stable, easy to prepare, low cost, suitable for low µM ferrate concentrations, and producing less hazardous waste.
  • Against the titration benchmark of 17.3 ± 0.1 mM ferrate, direct UV-Vis gave 16.9 ± 0.4 mM, ABTS gave 17.32 ± 0.03 mM, and NaI gave 17.27 ± 0.08 mM.
  • Direct UV-Vis at 505 nm is limited by low molar absorptivity and cannot quantify samples below 70 µM Fe(VI); ABTS at 415 nm reaches absorbance ~1 with only 35 µM ferrate, while NaI at 351 nm requires 27 µM, compared with 700 µM for direct UV-Vis.
  • Centrifuging improved quantification in the presence of Fe(III): titration gave 1.25 mM centrifuged vs 1.11 mM non-centrifuged; direct UV-Vis gave 1.22 mM vs 1.08 mM; for NaI at 5 µL, absorbance was 0.170 (4.2 µM) vs 0.120 (3.1 µM); for ABTS, 0.140 (3.5 µM) vs 0.120 (2.9 µM).

Methods

  • Electrochemical ferrates were generated in a two-compartment glass cell separated by a Nafion NR-112 cation exchange membrane, using a carbon steel anode and stainless steel cathode in 14 M NaOH, galvanostatically at 10 mA cm⁻² for 24 hours.
  • Four quantification methods were tested: modified Schreyer titrimetric analysis, direct ferrate UV-Vis at 505 nm, indirect ABTS UV-Vis at 415 nm, and modified indirect NaI UV-Vis at 351 nm using a pH 9 phosphate buffer.
  • Absorbance measurements used a Cary 100 spectrophotometer with 1 cm quartz cells; methods were compared for preparation time, test time, waste, toxicity, stability, accuracy, precision, range, and consumables cost.

Limitations

  • Stated in the paper: titration is time-consuming (~40 min), requires at least 5 mL of ferrate solution, uses hazardous acids and toxic Cr(VI), and costs about $30 USD per trial; direct UV-Vis has low molar absorptivity, cannot measure below 70 µM, and is subject to colloidal Fe(III) interference; ABTS solution is unstable and must be used fresh within about 30 minutes, generates organic waste, and costs about $3 USD per trial; conventional NaI is only applicable at pH 5.5–9.3, requiring the paper’s pH 9 buffer modification.
  • Evident from the text: the comparison relies on consumables cost and qualitative ratings, with uncertainty reported mainly as standard deviations from 3 or more measurements; the electrochemical ferrate matrix differs from the solid-ferrate solutions for which the original methods were developed.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1139/cjc-2016-0315

Cites

17 of 17 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

1 of 31 cited sources checked · 0 supported · 1 flagged · accuracy not yet measured

  • Findingcitation

    The ABTS absorption maxima occur at about 415 nm.

    “The maxima of the spectra for ABTS occur at about 415 nm in agreement with the results reported by Lee et.al 20 .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingnone given

    The direct colorimetric method provides more accurate measurements for concentrations higher than 100 μM.

    “The direct colorimetric method provides more accurate measurements for concentrations higher than 100 µM.”
    Quote in the paperNot a substantial claim
  • Findingnone given

    The titration method requires at least 5 mL of ferrate solution for a single measurement.

    “In addition, this method requires at least 5 mL of ferrate solution for a single measurement, thus making it difficult to do multiple quantifications with small samples”
    Quote in the paperSubstantial claim
  • Findingown data

    The molar absorptivity at 351 nm is 0.0396 μM cm -1 (R 2 =0.9972).

    “The molar absorptivity at 351 nm is 0.0396 µM cm -1 (R 2 =0.9972).”
    Quote in the paperSubstantial claim
  • Findingnone given

    For testing at pH higher than 9, no I 3 - peak was observed.

    “However, for testing at pH higher than 9 no I 3 -peak was observed.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one. 26
  • Probably not a substantial claim. 9

  • It may state two separate claims as one.

    Premisecitation

    The titrimetric method proposed by Schreyer is considered the most accurate method for quantification of ferrates and has been used as a standard procedure to benchmark other methods.

    “The titrimetric method proposed by Schreyer et al.(J.M. Schreyer, G. W. Thompson', 1950) is considered the most accurate method for quantification of ferrates”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [14] source

      The Introduction says the paper’s amperometric method has better precision and accuracy than the volumetric chromite method, and the Results and discussion report better reproducibility for the amperometric method. The Titration procedure confirms that the chromite method was used for comparison, but the paper does not call it the most accurate method; it says the opposite for the methods compared. Page numbers are unavailable in our copy. (LLM, conf=0.86)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured

  • It may state two separate claims as one.

    Findingreasoning

    The direct ferrate UV-Vis technique provides adequate accuracy and moderate precision, but due to its low molar absorptivity it is not possible to quantify samples with concentrations smaller than 70 μM of Fe (VI).

    “The direct ferrate UV-Vis technique provides adequate accuracy and moderate precision. Due to its low molar absorptivity, it is not possible to quantify samples with concentrations smaller than 70 µM of Fe (VI) by the direct UV-Vis colorimetric method.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingreasoning

    The NaI method requires a 27 μM solution of ferrate for an absorbance around 1, compared to the 700 μM concentration required by direct UV-Vis ferrate spectrophotometry.

    “The NaI method requires a 27 µM solution of ferrate for an absorbance around 1, compared to the 700 µM concentration required by direct UV-Vis ferrate spectrophotometry.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data

    In the NaI method for 5 μL, the centrifuged ferrate solution resulted in an absorbance of 0.170, compared to the non-centrifuged value of 0.120, corresponding to 4.2 μM and 3.1 μM respectively.

    “In the case of NaI (Figure 8a) for 5µL, the centrifuged ferrate solution resulted in an absorbance of 0.170, compared to the non-centrifuged value of 0.120, corresponding to 4.2 µM and 3.1 µM respectively.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds. It may state two separate claims as one.

    Findingnone given

    The costs associated with the NaI technique compared to the ABTS method are significantly lower; NaI costs about $1 USD per gram whereas ABTS costs about $60 USD per gram.

    “Furthermore, the costs associated with this technique, compared to the ABTS method, are significantly lower.The cost of NaI is about $1 USD per gram whereas that of ABTS is about $60 USD per gram.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    For the direct colorimetric method, the concentration of the centrifuged ferrate solution was 1.22 mM while the non-centrifuged solution had a concentration of 1.08 mM.

    “For the direct colorimetric method the concentration of the centrifuged ferrate solution was 1.22 mM while the non-centrifuged solution had a concentration of 1.08 mM.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    The ferrate spectra show a maximum at 505 nm and two minima at 390 nm and 670 nm.

    “The ferrate spectra show a maximum at 505 nm and two minima at 390 nm and 670 nm in close agreement with previous studies 13 .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Findingnone given

    The cost of consumables for the titration method is estimated to be about $30 USD per trial.

    “The cost of consumables involved for this method is estimated to be about $30 USD per trial.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    In the ABTS method, the centrifuged ferrate solution gave an absorbance of 0.140 (3.5 μM) and the non-centrifuged gave 0.120 (2.9 μM).

    “A similar effect was obtained with the ABTS method, i.e., an absorbance of 0.140 (3.5 µM) and 0.120 (2.9 µM) for the centrifuged and non-centrifuged ferrate solutions, respectively.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingreasoning

    A ferrate solution of 700 μM has an absorption value of around 1, whereas ABTS + reaches the same value of absorption with a ferrate concentration of only 35 μM.

    “A ferrate solution of 700 µM has an absorption value of around 1, whereas ABTS + reaches the same value of absorption with a much smaller ferrate concentration of only 35 µM.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. It may state two separate claims as one.

    Findingnone given

    Analyzing multiple samples with the ABTS method is time consuming and generates a lot of organic chemical waste coming from ABTS.

    “Furthermore, analyzing multiple samples is time consuming and generates a lot of organic chemical waste coming from ABTS.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Findingnone given

    The cost of consumables for the ABTS method is estimated to be about $3 USD per trial.

    “The cost of consumables involved for this method is estimated to be about $3 USD per trial.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    The ABTS + radical has a higher molar absorptivity than ferrate, allowing for better sensitivity and more accurate results with low ferrate concentrations.

    “The ABTS + radical has a higher molar absorptivity than ferrate, allowing for better sensitivity and more accurate results with low ferrate concentrations”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingreasoning

    The indirect NaI UV-Vis method is stable, easy to make, environmentally benign, does not lead to harmful wastes, and is ideal for water treatment applications.

    “The indirect NaI UV-Vis method is a very good option because it is stable, easy to make, environmentally benign, and does not lead to harmful wastes.For UV-Vis measurements, smaller concentrations of ferrate are required resulting in smaller concentrations of ferrate that can be detected, thus making it ideal for water treatment applications.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Findingnone given

    The cost of consumables for the direct UV-Vis method is estimated to be about $0.1 USD per test.

    “The cost of consumables involved for this method is low and estimated to be about $0.1 USD per test.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Findingnone given

    The NaI method can be carried out using just 4 mL of a 0.1 M NaI buffer pH 9 solution, decreasing the quantity of generated waste.

    “The NaI method can also be carried out using just 4 mL of a 0.1 M NaI buffer pH 9 solution, decreasing the quantity of generated waste.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Findingnone given

    The cost of consumables for the NaI method is estimated to be about $0.1 USD per trial.

    “The cost of consumables involved for this method is estimated to be about $0.1 USD per trial.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    The ferrate concentrations of the centrifuged and non-centrifuged samples, using the chemical titration method, were 1.25 mM and 1.11 mM, respectively.

    “The ferrate concentrations of the centrifuged and non-centrifuged samples, using the chemical titration method, were 1.25 mM and 1.11 mM, respectively.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper may give no reason why it holds.

    Findingnone given

    The waste generated from the NaI method is significantly less hazardous than that of other quantification methods.

    “The waste generated from this method is also significantly less hazardous than that of other quantification methods.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingnone given

    The indirect ABTS-based spectrophotometric method is very simple, efficient, and highly accurate, but the ABTS solution is not stable and degradation will lead to erroneous results.

    “The indirect ABTS-based spectrophotometric method is a very simple, efficient, and a highly accurate method.However, the ABTS solution is not stable and degradation of the ABTS solution will lead to erroneous results.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    ABTS solutions are unstable and must be used within 30 minutes after preparation.

    “however ABTS solution are unstable and must be used within 30 minutes after preparation 12,13,18 .”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [12] source
    • cites [13] source
    • cites [18] source

  • It may state two separate claims as one.

    Premisecitation

    Ozonation is ineffective in alkaline conditions and may result in the formation of carcinogenic bromates when bromides ions are present in water.

    “Ozonation is an alternative disinfection method, but it is ineffective in alkaline conditions and may result in the formation of carcinogenic bromates when bromides ions are present in water 1 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Sharma V. K., 2005, J. Water Health source

  • It may state two separate claims as one.

    Premisecitation

    The wet chemical method for ferrate production has a relatively low yield (10-15%) and requires additional reagents and further steps to purify and separate the desired product, leading to high costs.

    “This process has a is relatively low yield (10-15%) and additional reagents and further steps are required to further purify and separate the desired product, leading to high costs 1 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Sharma V. K., 2005, J. Water Health source

  • Probably not a substantial claim. It may state two separate claims as one.

    Premisenone given

    Electrochemical generation of ferrates requires neither hazardous reagents nor high temperatures.

    “Electrochemical generation of ferrates is an attractive alternative method of preparation, because it requires neither hazardous reagents nor high temperatures.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    Dry thermal synthesis of ferrate (VI) is expensive because of high energy consumption and dangerous due to potential detonation at high temperatures.

    “On the other hand, dry thermal synthesis of ferrate (VI) is performed at elevated temperatures (370 °C), and is considered to be expensive because of high energy consumption, and it is dangerous due to potential detonation at high temperatures 8 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8] source

  • It may state two separate claims as one.

    Premisecitation

    The ferrate solution tends to decompose to yield colloidal Fe (III) oxides, which can interfere with the spectral measurements.

    “In addition, the ferrate solution tends to decompose to yield colloidal Fe (III) oxides, which can interfere with the spectral measurements 19 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Traditional chlorination treatment processes have challenges including high dosages and long contact time, which lead to the formation of carcinogenic disinfection byproducts (DBPs) such as trichloromethanes.

    “Challenges with the use of traditional chlorination treatment processes include high dosages and long contact time, which lead to the formation of carcinogenic disinfection byproducts (DBPs) such as trichloromethanes 1 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Sharma V. K., 2005, J. Water Health source

  • It may state two separate claims as one.

    Interpretationown data

    Centrifuging the ferrate solution in the presence of Fe (III) helps in physical separation of insoluble species from the solution and leads to higher absorbance values.

    “Centrifuging the ferrate solution in the presence of Fe (III) helps in physical separation of insoluble species from the solution and leads to higher absorbance values.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    Phosphates stabilize Fe (III) by surface complexation, avoiding the formation of hydroxides that can interfere in the UV-VIS reading.

    “Phosphates stabilize Fe (III) by surface complexation 21 , avoiding the formation of hydroxides that interfer in the UV-VIS reading 18 .”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [21]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18] source

  • It may state two separate claims as one.

    Interpretationreasoning

    The NaI and ABTS methods measure the absorbance of the I 3 - and ABTS + ions generated as a result of chemical reactions with ferrate, allowing them to account only for the presence of ferrate while any Fe (III) ions are left unreacted.

    “The NaI and ABTS methods measure the absorbance of the I 3 -and ABTS + ions, respectively, which are generated as a result of chemical reactions with ferrate.This allows for the ability to account only for the presence of ferrate while any Fe (III) ions are left unreacted.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    Ferrates have a high standard half-cell reduction potential (2.20 V vs. SHE), non-toxic reduction byproducts (Fe 3+ ), and the simultaneous capacity to act as both an oxidant and coagulant agent.

    “The suitability of ferrates is a consequence of their unique properties such as: a) a high standard half-cell reduction potential (2.20 V vs. SHE), b) non-toxic reduction byproducts (Fe 3+ ), and c) the simultaneous capacity to act as both an oxidant and coagulant agent 3 .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] source
31 of 31

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • ABTS cost per trial conflicts with Table 1

    Major

    The text estimates ABTS consumables at $3 per trial, but Table 1 lists $0.5 per sample under Indirect ABTS.

  • NaI cost per trial conflicts with Table 1

    Major

    The text estimates NaI consumables at $0.1 per trial, but Table 1 lists $3 per sample under Indirect NaI.

  • NaI centrifuging difference exceeds the stated limit

    Minor

    The stated NaI concentrations differ by 1.1 μM (4.2 minus 3.1), contradicting the claim that the difference was lower than 1 μM in both methods.

  • Two blank-absorbance values are assigned the same path length

    Minor

    The ABTS replacement criterion gives both 0.02 and approximately 0.2 as the blank absorbance in a 10 cm path length.

  • Two different NaI buffer recipes are given

    Minor

    The experimental section specifies 995 mL of phosphate solution plus 45 mL of HCl, whereas the results section specifies 955 mL plus 45 mL for the modified NaI buffer.

5 of 5

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Metadata

Authors
Cataldo Hernández, M. A., May, A., Bonakdapour, A., Mohseni, M., & Wilkinson, D. P.
Affiliations
  • Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
  • University of British Columbia (CA)
ORCID
Venue
Canadian Journal of Chemistry
Publisher
Canadian Science Publishing
Published
2017-01
Volume
95
Issue
1
Pages
105-112
ISSN
  • 0008-4042 (ISSN-L)
  • 1480-3291
DOI
10.1139/cjc-2016-0315
OpenAlex
W2546201748
Cited by
14
References
17
Citations by year
2026: 1 · 2023: 1 · 2020: 6 · 2019: 2 · 2018: 3 · 2017: 1
FWCI
1.11
Type
journal article
Language
en
Update notices
correction (2017-09-23)
Open access
Licence
www.nrcresearchpress.com/page/about/CorporateTextAndDataMining (tdm)
Locations
  • Canadian Journal of Chemistry (publishedVersion)
  • TSpace (University of Toronto) (acceptedVersion)
Funders
  • Universities Space Research Association
  • Natural Sciences and Engineering Research Council of Canada
Topics
  • Physical Sciences › Environmental Science › Water Science and Technology › Advanced oxidation water treatment
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Water Treatment and Disinfection
  • Physical Sciences › Environmental Science › Water Science and Technology › Environmental and Analytical Chemistry Studies
Keywords
drinking water treatment, titration, colorimetric assay, ABTS, sodium iodide, UV-Vis spectroscopy, analytical method comparison

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