Partition of a mixture of chlorinated organic compounds in real contaminated soils between soil and aqueous phase using surfactants: Influence of pH and surfactant type

García-Cervilla, Raúl; Santos, Aurora; Salvador, Alfredo; Lorenzo, David

doi:10.1016/j.jece.2021.105908

Cited by 19 publications

(18 citation statements)

References 45 publications

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“…The addition of alkali could be considered a first step to enhancing the volatility of the more highly chlorinated compounds. It was experimentally proved that alkaline pH (>12) promotes the reaction of HCH and PentaCXs to TCBs and HeptaCHs and HexaCXs to TetraCBs in the absence and presence of the surfactant. , TCB and TetraCB compounds presented lower risks and lower boiling points than the parent COCs. García-Cervilla et al studied the transformation of DNAPL-R at pH 12 in the presence of the surfactant, observing distributing changes since PentaCX, HexaCX, HCH, and HeptaCH isomers were not detected in the aqueous emulsion under alkaline conditions, while the TCB and TetraCB molar percentage was increased under these conditions.…”

Section: Resultsmentioning

confidence: 99%

“…NaOH was used to promote the alkaline dehydrochlorination of HCHs and PentaCXs to TCBs and HeptaCHs and HexaCXs and HeptaCHs to TetraCBs, which reduced the toxicity of the effluent to be treated and increased the volatility of the COCs in the aqueous phase. 30 The composition of DNAPL-R after the alkalinization treatment (i.e., xi pH > 12) is summarized in Table S1.…”

Section: Industrial and Engineeringmentioning

confidence: 99%

“…The amount of solubilized COCs in a saturated emulsion is linear with the surfactant concentration at alkaline pH. 30 Therefore, the decrease in the surfactant concentration with time produces a decrease in the COCs in the emulsion C D when saturated emulsions are used at zero time. The remaining surfactant concentration with time C D can be calculated using eq 8.…”

Section: Effect Of Temperaturementioning

confidence: 99%

“…28 In previous studies, it was reported that alkali addition could be considered to enhance the volatility of the more chlorinated compounds since it promotes their dehydrochlorination to more volatile compounds in the aqueous and soil phases 29 and emulsion with E3, Tween-80, and SDS. 30 This effect can be managed by air stripping the contaminated emulsions obtained after SEAR treatment of sites polluted with DNAPL waste from lindane production. However, the alkali, surfactant concentrations, and temperature could affect the surfactant stability and the volatility of the COCs in the emulsion.…”

Section: Introductionmentioning

confidence: 99%

“…In this place, the liquid wastes of lindane production, containing 28 COCs, were dumped in unlined landfills, migrating vertically through the aquifer as dense NAPLs (DNAPLs) and polluting the nearby area . In previous studies, it was reported that alkali addition could be considered to enhance the volatility of the more chlorinated compounds since it promotes their dehydrochlorination to more volatile compounds in the aqueous and soil phases and emulsion with E3, Tween-80, and SDS . This effect can be managed by air stripping the contaminated emulsions obtained after SEAR treatment of sites polluted with DNAPL waste from lindane production.…”

Section: Introductionmentioning

confidence: 99%

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Treatment of a Complex Emulsion of a Surfactant with Chlorinated Organic Compounds from Lindane Wastes under Alkaline Conditions by Air Stripping

Sáez

García-Cervilla

Santos

et al. 2023

Ind. Eng. Chem. Res.

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Surfactant-enhanced aquifer remediation is commonly applied in polluted sites with dense non-aqueous phase liquids (DNAPLs). This technique transfers the contamination from subsoil to an extracted emulsion, which requires further treatment. This work investigated the treatment of a complex emulsion composed of a nonionic surfactant and real DNAPL formed of chlorinated organic compounds (COCs) and generated as a lindane production waste by air stripping under alkaline conditions. The influence of the surfactant (1.5–15 g·L–1), COC concentrations (2.3–46.9 mmol·L–1), and temperature (30–60 °C) on the COC volatilization was studied and modeled in terms of an apparent constant of Henry at pH > 12. In addition, the surfactant stability was studied as a function of temperature (20–60 °C) and surfactant (2–10 g·L–1), COC (0–70.3 mmol·L–1), and NaOH (0–4 g·L–1) concentrations. A kinetic model was successfully proposed to explain the loss of surfactant capacity (SCL). The results showed that alkali and temperature caused the SCL by hydrolysis of the surfactant molecule. The increasing surfactant concentration decreased the COC volatility, whereas the temperature improved the COC volatilization. Finally, the volatilization of COCs in alkaline emulsions by air stripping (3 L·h–1) was performed to evaluate the treatment of an emulsion composed of the COCs (17.6 mmol·kg–1) and surfactant (3.5 and 7 g·L–1). The air stripping was successfully applied to remove COCs (>90%), reaching an SCL of 80% at 60 °C after 8 h. Volatilization can remove COCs from emulsions and break them, enhancing their further disposal.

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Section: Resultsmentioning

confidence: 99%

Section: Industrial and Engineeringmentioning

confidence: 99%

Section: Effect Of Temperaturementioning

confidence: 99%