Removal of chromium(VI) from drinking water by redox-assisted coagulation with iron(II)

Giehyeon Lee, Janet G. Hering

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Batch experiments were conducted to determine whether sub-ppb concentrations of dissolved Cr(VI) could be achieved by redox-assisted coagulation with Fe(II). In this process Fe(II) acts as a reductant for Cr(VI) and, after its oxidation to Fe(III), as a coagulant. With an Fe(II) dose of 30 μM (1.7 mg/l as Fe), dissolved Cr(VI) concentrations in synthetic or natural Colorado River water (CRW) at pH 8.2 could be decreased from an initial value of 1 μM (52 μg/l) to <0.01 μM (<0.5 μg/l) corresponding to a >99% removal efficiency. In contrast, removal of Cr(VI) by coagulation with Fe(III) was poor, even at higher Fe(III) doses (up to 100 μM). The efficiency of Cr(VI) removal by redox-assisted coagulation decreased at lower (but still above stoichiometric) Fe(II) doses due to the incomplete reduction of Cr(VI) to Cr(III), which, under our experimental conditions, can be attributed to the competing reaction of Fe(II) with O2 between pH 7 and 8.2 and to the slow kinetics of reaction of Fe(II) with Cr(VI) between pH 6.5 and 7. Although Cr(VI) was less efficiently removed from natural or synthetic CRW than from the simple electrolyte solution, the desired level of removal could be achieved by increasing the Fe(II) dose.

Original languageEnglish
Pages (from-to)319-332
Number of pages14
JournalJournal of Water Supply: Research and Technology - AQUA
Volume52
Issue number5
Publication statusPublished - 2003 Aug 1

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Coagulation
Potable water
Drinking Water
coagulation
Oxidation-Reduction
chromium
Chromium
Iron
drinking water
iron
river water
Rivers
electrolyte
Water
Electrolytes
oxidation
kinetics
Oxidation
Coagulants
Kinetics

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Water Science and Technology

Cite this

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abstract = "Batch experiments were conducted to determine whether sub-ppb concentrations of dissolved Cr(VI) could be achieved by redox-assisted coagulation with Fe(II). In this process Fe(II) acts as a reductant for Cr(VI) and, after its oxidation to Fe(III), as a coagulant. With an Fe(II) dose of 30 μM (1.7 mg/l as Fe), dissolved Cr(VI) concentrations in synthetic or natural Colorado River water (CRW) at pH 8.2 could be decreased from an initial value of 1 μM (52 μg/l) to <0.01 μM (<0.5 μg/l) corresponding to a >99{\%} removal efficiency. In contrast, removal of Cr(VI) by coagulation with Fe(III) was poor, even at higher Fe(III) doses (up to 100 μM). The efficiency of Cr(VI) removal by redox-assisted coagulation decreased at lower (but still above stoichiometric) Fe(II) doses due to the incomplete reduction of Cr(VI) to Cr(III), which, under our experimental conditions, can be attributed to the competing reaction of Fe(II) with O2 between pH 7 and 8.2 and to the slow kinetics of reaction of Fe(II) with Cr(VI) between pH 6.5 and 7. Although Cr(VI) was less efficiently removed from natural or synthetic CRW than from the simple electrolyte solution, the desired level of removal could be achieved by increasing the Fe(II) dose.",
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Removal of chromium(VI) from drinking water by redox-assisted coagulation with iron(II). / Lee, Giehyeon; Hering, Janet G.

In: Journal of Water Supply: Research and Technology - AQUA, Vol. 52, No. 5, 01.08.2003, p. 319-332.

Research output: Contribution to journalArticle

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