Evidence of precipitate formation and byproduct transfer to nonaqueous phase liquids as a result of persulfate exposure
Notice bibliographique
Résumé
Abstract For optimal treatment of a source zone using in situ chemical oxidation (ISCO), the oxidant needs to be delivered as close to the nonaqueous phase liquid (NAPL) as possible to enhance the rate of dissolution. However, the interaction between the oxidant and NAPL may result in physical and chemical changes that affect both treatment effectiveness and post‐treatment dissolution behavior from remnant NAPL. Due to a host of favorable attributes, persulfate is frequently selected as the preferred oxidant but little is known about changes that can occur when persulfate interacts with a NAPL. In this study, two series of static batch experiments were conducted. In the first series, NAPL collected from a former manufactured gas plant (FMGP) site was exposed to a persulfate solution for ~60 days, while in the second series, individual and a mixture of pure organic liquids were exposed to a persulfate solution for ~50 days. It was observed that dark‐brown precipitates were formed in almost all the experimental systems. Notably, a layer of precipitates accumulated along the NAPL/water interface in the FMGP NAPL system and inhibited dissolution. In some of the pure organic liquid systems, the aqueous phase appeared yellow and precipitates were formed. Precipitate formation was attributed to the polymerization of aromatic compounds initiated by sulfate and hydroxyl radicals. Although precipitate formation is detrimental to mass transfer, surfactant‐like byproducts which may also be produced could lead to an emulsified aqueous phase, thereby enhancing dissolution and altering NAPL/water surface tension. Several of the organic byproducts that were detected in the aqueous phase were also detected in the NAPL, suggesting that these byproducts which were generated in aqueous phase migrated into the NAPL. Depending on the concentration of these byproducts in the NAPL, they could impact important physical properties (e.g., viscosity and density) and affect NAPL composition, which can affect intra‐NAPL diffusion and post‐treatment dissolution behavior. Although additional investigation is required, the results from this study indicate that the impacts of byproducts generated when using persulfate in ISCO applications need to be considered.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».