Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3

Jeen, Sung‐Wook; Yang, YanQi; Gui, Lai; Gillham, Robert W.

doi:10.1016/j.jconhyd.2012.11.004

Cited by 19 publications

(12 citation statements)

References 39 publications

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“…The remediation rate of TCE decreased by 15% when 5 mg L −1 of selenate was added. It can be concluded that the accumulation of precipitates not only can affect the access of contaminants to the electrode surface but also, decrease porosity and hydraulic conductivity, which in turn restricts simulated groundwater flow [35]. …”

Section: Resultsmentioning

confidence: 99%

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Fallahpour

Mao

Rajić

et al. 2017

Journal of Environmental Chemical Engineering

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A small-scale flow-through limestone column was used to evaluate the effect of common coexisting organic and inorganic compounds on the electrochemical dechlorination of trichloroethylene (TCE) in karst media. Iron anode was used to produce ferrous ions and promote reducing conditions in the column. The reduction of TCE under 90 mA current, 1 mL min−1 flow rate, and 1 mg L−1 initial TCE concentration, was inhibited in the presence of humic acids due to competition for direct electron transfer and/or reaction with atomic hydrogen produced at the cathode surface by water electrolysis. Similarly, presence of 10 mg L−1 chromate decreased TCE reduction rate to 53%. The hexavalent chromium was completely reduced to trivalent chromium due to the ferrous species produced from iron anode. Presence of 5 mg L−1 selenate decreased the removal of TCE by 10%. Chromium and selenate complexation with dissolved iron results in formation of aggregates, which cover the electrodes surface and reduce TCE dechlorination rate. Presence of 40 mg L−1 nitrates caused reductive transformation of TCE up to 80%. Therefore, TCE removal is influenced by the presence of other contaminants that are present as a mixture in groundwater in the following order: humic acid, chromate, selenate, and nitrate.

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Section: Resultsmentioning

confidence: 99%

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Fallahpour

Mao

Rajić

et al. 2017

Journal of Environmental Chemical Engineering

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“…In MIN3P, reactions can be defined as equilibrium reactions or kinetically controlled reactions. MIN3P has been successfully used to interpret the multicomponent geochemical changes, including Ni reduction by granular iron [25], effects of chromate [26] and nitrate [27] on TCE degradation, and geochemical interactions of mine seepage water with an aquifer [28]. In this study, the database of MIN3P was modified to include the proposed reaction for the arsenic release from the aquifer sediments.…”

Section: Reactive Transport Modelingmentioning

confidence: 99%

Reactive Transport Modeling for Mobilization of Arsenic in a Sediment Downgradient from an Iron Permeable Reactive Barrier

Jeen

2017

Water

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Arsenic (As) can be naturally present in the native aquifer materials and can be released to groundwater through reduction dissolution of iron oxides containing As. While granular iron permeable reactive barriers (PRBs) can be effective for the treatment of arsenic in groundwater, the mobilization of arsenic in the sediment downgradient of the PRB might be an issue due to the reduced geochemical conditions generated by reactions in the PRB. The release of arsenic in the sediment downgradient from a proposed iron PRB was studied through laboratory column experiments and reactive transport modeling. The laboratory column experiments showed a significant removal of arsenic from the groundwater by granular iron (from the influent concentration of about 0.7 mg L −1 to less than 0.006 mg L −1 at the effluent); however, arsenic can be flushed out from the aquifer sediments (up to 0.09 mg L −1 ). The reactive transport modeling based on the geochemical reactions as suggested from the experiments, i.e., reductive dissolution of As-bearing goethite, was successful to reproduce the observed geochemical trends in the column experiments. This study can provide implications regarding the installation of iron PRBs to treat arsenic in groundwater and also be useful to understand geochemical behavior of arsenic under reduced conditions.

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“…According to Jeen et al (2013), dissolved CaCO 3 buffers pH, decreases the corrosion potential of ZVI and increases the degradation rates of TCE. Similar to column 1, the TCE reaction rate decreased as the simulation time increased; however, the change in this column can be attributed to the effects of dissolved carbonate species in the source water, as will be discussed later.…”

Section: Reaction Rate Constantsmentioning

confidence: 99%

Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model

Hwang

Jeen

Sudicky

et al. 2015

Journal of Contaminant Hydrology

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Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3

Cited by 19 publications

References 39 publications

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Reactive Transport Modeling for Mobilization of Arsenic in a Sediment Downgradient from an Iron Permeable Reactive Barrier

Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model

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