IN SITU Chemical Oxidation

Siegrist, Robert L.; Crimi, Michelle; Thomson, Neil R.; Clayton, Wilson S.; Marley, Michael C.

doi:10.1007/978-1-4614-6922-3_9

Cited by 13 publications

(15 citation statements)

References 138 publications

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“…Among the two, oxidation of Fe(0) by water represents the major fraction of NRD because Fe(0) corrodes in water and water is essentially unlimited. This makes NRD different from NOD (natural oxidant demand), a conceptually similar term used in in situ chemical oxidation (ISCO), as NOD is mainly contributed by indigenous oxidizable materials (e.g., organic matter), which are finite (Siegrist et al., ). Therefore, compared to NOD, whose impacts are commonly mitigated by applying excess oxidant in ISCO, the impacts of NRD cannot be effectively alleviated by adding excess nZVI in ISCR because water cannot be exhausted.…”

Section: Reducing Capacity Natural Reductant Demand and Electron Efmentioning

confidence: 99%

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Fan¹,

O'Carroll

Elliott

et al. 2016

Remediation

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Nano zerovalent iron (nZVI) is a promising remediation technology utilizing in situ chemical reduction (ISCR) to clean up contaminated groundwater at hazardous waste sites. The small particle size and large surface area of nZVI result in high reactivity and rapid destruction of contaminants. Over the past 20 years, a great deal of research has advanced the nZVI technology from bench‐scale tests to field‐scale applications. However, to date, the overall number of well‐characterized nZVI field deployments is still small compared to other alternative remedies that are more widely applied. Apart from the relatively high material cost of nZVI and questions regarding possible nanotoxicological side effects, one of the major obstacles to the widespread utilization of nZVI in the field is its short persistence in the environment due to natural reductant demand (NRD). The NRD for nZVI is predominantly due to reduction of water, but other reactions with naturally present oxidants (e.g., oxygen) occur, resulting in situ conditions that are reducing (high in ferrous iron phases and H2) but with little or no Fe(0). This article reviews the main biogeochemical processes that determine the selectivity and longevity of nZVI, summarizes data from prior (laboratory and field) studies on the longevity of various common types of nZVI, and describes modifications of nZVI that could improve its selectivity and longevity for full‐scale applications of ISCR. © 2016 Wiley Periodicals, Inc.

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Section: Reducing Capacity Natural Reductant Demand and Electron Efmentioning

confidence: 99%

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Fan¹,

O'Carroll

Elliott

et al. 2016

Remediation

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“…In situ chemical oxidation (ISCO) has been used for several decades for the remediation of contaminated groundwater and aquifer solids. 1 Recently, persulfate (S 2 O 8 2− ) has become popular as an oxidant in ISCO systems due to its ability to oxidize a variety of contaminants. 2-3 When persulfate is injected into the subsurface without any other additives, it is activated by Fe(III)- and Mn(IV)-containing oxides to produce sulfate radical (SO 4 •− ), 4-5 an oxidant that reacts with a variety of contaminants.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products

Liu

Bruton²,

et al. 2016

Environ. Sci. Technol.

282

113

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Sulfate radical (SO4(•-)) is a strong, short-lived oxidant that is produced when persulfate (S2O8(2-)) reacts with transition metal oxides during in situ chemical oxidation (ISCO) of contaminated groundwater. Although engineers are aware of the ability of transition metal oxides to activate persulfate, the operation of ISCO remediation systems is hampered by an inadequate understanding of the factors that control SO4(•-) production and the overall efficiency of the process. To address these shortcomings, we assessed the stoichiometric efficiency and products of transition metal-catalyzed persulfate oxidation of benzene with pure iron- and manganese-containing minerals, clays, and aquifer solids. For most metal-containing solids, the stoichiometric efficiency, as determined by the loss of benzene relative to the loss of persulfate, approached the theoretical maximum. Rates of production of SO4(•-) or hydroxyl radical (HO(•)) generated from radical chain reactions were affected by the concentration of benzene, with rates of S2O8(2-) decomposition increasing as the benzene concentration increased. Under conditions selected to minimize the loss of initial transformation products through reaction with radicals, the production of phenol only accounted for 30%-60% of the benzene lost in the presence of O2. The remaining products included a ring-cleavage product that appeared to contain an α,β-unsaturated aldehyde functional group. In the absence of O2, the concentration of the ring-cleavage product increased relative to phenol. The formation of the ring-cleavage product warrants further studies of its toxicity and persistence in the subsurface.

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“…S‐ISCO, an EthicalChem (South Windsor, CT) patented technology, is a simultaneous surfactant‐oxidant application approach, and is well suited to permanently meeting site cleanup objectives for soil and groundwater by significantly enhancing contaminant contact with the oxidant. Contaminant solubilization by surfactants brings immiscible organics into the groundwater phase making them available to the simultaneously injected aqueous oxidants; thereby, enabling a more efficient rate and extent of oxidation (Siegrist et al., ). Desorbed contaminants become immediately available in the aqueous phase for reaction with the simultaneously injected oxidant, while emulsification of contaminants significantly increases the surface area of contaminant available to the oxidant; thereby, increasing the oxidant efficiency.…”

Section: Overview Of S‐iscomentioning

confidence: 99%

“…For combined surfactant‐oxidant application, compatibility of surfactants with the oxidants is an important factor to be considered. Several studies that tested and documented chemical compatibility between various surfactants and oxidants have recognized alcohol‐based surfactants to be more susceptible to reactions with oxidants, thus, making them unfavorable for simultaneous applications with the oxidants (Siegrist et al., ; Zai et al., ). Surfactants used during the S‐ISCO process are plant‐based solvent/co‐solvent blends and have shown compatibility with the most commonly used oxidants, such as sodium persulfate and hydrogen peroxide.…”

Section: Overview Of S‐iscomentioning

confidence: 99%

“…While pump and treat was initially the most common approach used for contaminated groundwater cleanups, several strategies for destruction of contaminants using in situ chemical oxidation (ISCO) approaches have emerged in recent years. Many organic contaminants are predisposed to decomposition though reactions with oxidants making ISCO remediation viable for some aspects of remediation (Siegrist et al., ). However, contaminant rebound, which causes groundwater contaminant concentrations to increase after ISCO treatments, is an undesirable but a commonly anticipated outcome of ISCO remediation.…”

Section: Introductionmentioning

confidence: 99%

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Surfactant‐Oxidant Co‐Application for Soil and Groundwater Remediation

Dahal

Holcomb

Socci

2016

Remediation Journal

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In situ chemical oxidation (ISCO) typically delivers oxidant solutions into the subsurface for contaminant destruction. Contaminants available to the oxidants, however, are limited by the mass transfer of hydrophobic contaminants into the aqueous phase. ISCO treatments therefore often leave sites with temporarily clean groundwater which is subject to contaminant rebound when sorbed and free phase contaminants leach back into the aqueous phase. Surfactant Enhanced In situ Chemical Oxidation (S-ISCO R⃝ ) uses a combined oxidant-surfactant solution to provide optimized contaminant delivery to the oxidants for destruction via desorption and emulsification of the contaminants by the surfactants. This article provides an overview of S-ISCO technology, followed by an implementation case study at a coal tar contaminated site in Queens, New York. Included are data points from the site which demonstrate how S-ISCO delivers desorbed contaminants without uncontrolled contaminant mobilization, as desorbed and emulsified contaminants are immediately available to the simultaneously injected oxidant for reaction. c⃝

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IN SITU Chemical Oxidation

Cited by 13 publications

References 138 publications

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products

Surfactant‐Oxidant Co‐Application for Soil and Groundwater Remediation

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