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Title: Fate of phthalate esters in landfill leachate under subcritical and supercritical conditions and determination of transformation products
Authors: Ateş, Havva
Argun, Mehmet Emin
Keywords: Cost
Emerging micropollutants
Non-target analysis
Transformation of PAEs
Transformation products
Leachate treatment
Emerging micropollutant
Non-target analysis
Phthalate ester
Supercritical water oxidation
Transformation of phthalate ester
Transformation products
Chemical oxygen demand
4-boronic acid benzophenone
di-n-octyl phthalate
phenyl-2-aminoethyl sulfide
phthalic acid
phthalic acid benzyl butyl ester
phthalic acid bis(2 ethylhexyl) ester
water pollutant
Diethylhexyl Phthalate
Water Pollutants, Chemical
Issue Date: 2023
Publisher: Elsevier Ltd
Abstract: The hypothesis of this study is that the complex organic load of landfill leachate could be reduced by supercritical water oxidation (SCWO) in a single stage, but this operation could lead to the formation of some undesired by-products of phthalate esters (PAEs). In this context, the fate of selected PAEs, butyl benzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), was investigated during the oxidation of leachate under subcritical and supercritical conditions. Experiments were conducted at various temperatures (250–500 °C), pressures (10–35 MPa), residence times (2–18 min) and dimensionless oxidant doses (DOD: 0.2–2.3). The SCWO process decreased the leachate's chemical oxygen demand (COD) from 34,400 mg/L to 1,120 mg/L (97%). Removal efficiencies of DEHP and DNOP with longer chains were higher than BBP. The DEHP, DNOP and BBP compounds were removed in the range of −35 to 100%, −18 to 92%, and 28 to 36%, respectively, by the SCWO process. Many non-target PAEs were qualitatively detected in the raw leachate apart from the selected PAEs. Besides, 97% of total PAEs including both target and non-target PAEs was mineralized at 15 MPa, 300 °C and 5 min. Although PAEs were highly mineralized during SCWO of the leachate, aldehyde, ester, amide and amine-based phthalic substances were frequently detected as by-products. These by-products have transformed into higher molecular weight by-products with binding reactions as a result of complex SCWO process chemistry. It has also been determined that some non-target PAEs such as 1,2-benzenedicarboxylic acid bis(2-methylpropyl)ester and bis(2-ethylhexyl) isophthalate can transform to the DEHP. Therefore, the suggested pathway in this study for PAEs degradation during the SCWO of the leachate includes substitution and binding reactions as well as an oxidation reaction. © 2022 Elsevier Ltd
ISSN: 0956-053X
Appears in Collections:Mühendislik ve Doğa Bilimleri Fakültesi Koleksiyonu
PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collections
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collections
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collections

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