Oxidation of aqueous EDTA and associated organics and coprecipitation of inorganics by ambient iron-mediated aeration

James Douglas Englehardt, Daniel E. Meeroff, Luis Echegoyen, Yang Deng, Francisco Raymo, Tomoyuki Shibata

Research output: Contribution to journalArticle

78 Citations (Scopus)

Abstract

Cationic metal and radionuclide contaminants can be extracted from soils to groundwater with sequestering agents such as EDTA. However, EDTA must then be removed from the groundwater, by advanced oxidation or specialized biological treatment. In this work, aqueous individual metal-EDTA solutions were aerated with steel wool for 25 h, at ambient pH, temperature, and pressure. Removal of approximately 99% of EDTA (0.09-1.78 m M); glyoxylic acid (0.153 mM); chelated Cd2+ (0.94 and 0.0952 mM), Pb2+ (0.0502 mM), and Hg 2+ (0.0419 mM); and free chromate and vanadate was shown. EDTA was oxidized to glyoxylic acid and formaldehyde, and metals/metalloids were coprecipitated together with iron oxyhydroxide floe. Free arsenite and arsenate were each removed at 99.97%. Free Sr2+, and chelated Ni2+ were removed at 92% and 63%, respectively. Similar removals were obtained from mixtures, including 99.996 ± 0.004% removal of total arsenic (95% confidence). Traces of iminodiacetic acid, nitrilotriacetic acid, and ethylenediaminetriacetic acid were detected after 25 h. Results are consistent with first-order, solution-phase oxidation of EDTA and glyoxylic acid by ferryl ion and H2O2, respectively, with inhibition due to sludge accumulation, and equilibrium metal coprecipitation. This ambient process, to our knowledge previously unknown, agrees with recently reported findings and shows promise for remediation of metals, metalloids, and radionuclides in wastewater, soil, and sediment.

Original languageEnglish
Pages (from-to)270-276
Number of pages7
JournalEnvironmental Science and Technology
Volume41
Issue number1
DOIs
StatePublished - Jan 1 2007

Fingerprint

Ethylenediaminetetraacetic acid
Coprecipitation
EDTA
Edetic Acid
aeration
Iron
oxidation
iron
Metals
Oxidation
Acids
acid
Metalloids
metal
Radioisotopes
radionuclide
Groundwater
Sequestering Agents
Nitrilotriacetic Acid
Chromates

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Science(all)
  • Environmental Chemistry

Cite this

Oxidation of aqueous EDTA and associated organics and coprecipitation of inorganics by ambient iron-mediated aeration. / Englehardt, James Douglas; Meeroff, Daniel E.; Echegoyen, Luis; Deng, Yang; Raymo, Francisco; Shibata, Tomoyuki.

In: Environmental Science and Technology, Vol. 41, No. 1, 01.01.2007, p. 270-276.

Research output: Contribution to journalArticle

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