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Reductive decomposition of perfluorooctanoic acid (PFOA) during VUV-based processes : VUV 기반 공정에서의 perfluorooctanoic acid (PFOA)의 환원적 분해

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dc.contributor.advisor조경덕-
dc.contributor.author박흥주-
dc.date.accessioned2024-05-31T18:01:19Z-
dc.date.available2024-05-31T18:01:19Z-
dc.date.issued2023-
dc.identifier.other000000174931-
dc.identifier.urihttps://hdl.handle.net/10371/204017-
dc.identifier.urihttps://dcollection.snu.ac.kr/common/orgView/000000174931ko_KR
dc.description학위논문(석사) -- 서울대학교대학원 : 보건대학원 환경보건학과, 2023. 2. 조경덕.-
dc.description.abstractBecause of its high stability and persistence, PFOA is not easily degraded in the water. Hydrated electrons (eaq-) are known as strong reducing agents that can remove recalcitrant PFOA through reductive decomposition. In this study, the efficient removal and defluorination of PFOA were confirmed using eaq-, and the removal and defluorination rates were compared in the vacuum ultraviolet (VUV) photolysis, VUV/sulfite, VUV/sulfite/iodide processes. In the VUV photolysis process, 88.6 % of PFOA is removed within 6 hr, and the removal rate constant for this is 0.007 min-1. In the VUV/sulfite process, PFOA is all removed within 90 minutes, and the removal rate constant is 0.083 min-1. In the VUV/sulfite/iodide process, PFOA is all removed within 30 minutes, and the removal rate constant is 0.230 min-1. The defluorination rate for PFOA removal in VUV photolysis, VUV/sulfite, and VUV/sulfite/iodide process was 34.6 %, 72.7 %, and 73.9 % in 6 hr, respectively. Adding tert-butanol, NO2-, and NO3- as scavengers confirmed that eaq- can degrade PFOA most efficiently and can cause defluorination because it has strong reducing power.
In the VUV photolysis process, short-chain perfluoroalkyl carboxylic acids (PFCAs) were mainly produced as transformation products (TPs) by chain shortening mechanism. In the VUV/sulfite and VUV/sulfite/iodide processes, it was confirmed that 16 and 15 TPs were found respectively and were mainly generated through the mechanism of H-F exchange (e.g. TP377, TP395), SO3∙--F exchange (e.g. TP474), generation of an unsaturated compound (e.g. TP392, TP410, TP436), or hydration (e.g. TP393). Based on the results and TPs found in UPLC-QTOF/MS, PFOA degradation pathways are proposed in the VUV-based processes.
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dc.description.abstract수화 전자는 환원 분해를 통해 제거하기 어려운 과불화화합물을 제거할 수 있는 강력한 환원제로 알려져 있다. 본 연구에서는 수화 전자를 이용하여 대표적인 과불화화합물인 과불화옥탄산의 효율적인 제거 및 탈불화를 확인하였고, 진공 자외선 광분해, 진공 자외선 / 아황산염, 진공 자외선 / 아황산염 / 요오드화물 공정에서의 제거 및 탈불화율을 비교하였다.
진공 자외선 광분해 공정에서는 6시간 이내에 약 88.6%의 과불화옥탄산이 제거된 반면, 진공 자외선 / 아황산염 공정에서는 과불화옥탄산이 90분 이내에, 진공 자외선 / 아황산염 / 요오드화물 공정에서는 30분 이내에 완전히 제거되었다. 진공 자외선 광분해, 진공 자외선 / 아황산염 및 진공 자외선 / 아황산염 / 요오드화물 공정에서 과불화옥탄산을 제거를 위한 탈불소화율은 6시간 동안 각각 약 34.6%, 72.7% 및 73.9%이다. 제거제로 삼차 뷰틸 알코올, 아질산염 및 질산염을 추가하여 수화 전자가 과불화옥탄산을 가장 효율적으로 분해할 수 있음이 확인되었다.
진공 자외선 광분해 공정에서 짧은 사슬의 과불화카르복실산은 주로 사슬 단축 메커니즘을 통해 부산물로 생성된다. 진공 자외선 / 아황산염 및 진공 자외선 / 아황산염 / 요오드화물 공정에서는 주로 수소-불소 치환(예: 부산물 377, 부산물 395), 아황산염 라디칼-불소 치환(예: 부산물 474), 불포화 화합물(예: 부산물 392, 부산물 410, 부산물 436)의 생성, 수화 반응(예: 부산물 393)의 메커니즘을 통해 다양한 유형의 부산물이 생성됨을 확인했다.
위의 결과들과 사중극자 비행시간형 액체크로마토그래피/ 질량분석기에서 발견된 부산물을 기반으로 진공 자외선 기반 공정에서 과불화옥탄산 분해 경로가 제안되었다.
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dc.description.tableofcontents1. Introduction 1
1.1. Background 1
1.2. Objectives 7
2. Materials and methods 8
2.1. Chemicals 8
2.2. Photo-degradation of PFOA 9
2.3. Analytical methods 12
2.4. Theoretical calculation methods for identifying reactive sites 16
2.5. Toxicity assessment 17
3. Results and discussion 18
3.1 Degradation of PFOA in VUV-based processes 18
3.2 Effect of sulfite, iodide concentration 22
3.3 Effect of pH 28
3.4 The roles of reactive species in PFOA degradation 32
3.5 Degradation pathways and mechanism in VUV-based processes 35
3.6 Toxicity evaluation of PFOA and its TPs 49
4. Conclusions 52
5. References 53
Abstract in Korean 62
6. Supplementary materials 64
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dc.format.extentⅴ, 76-
dc.language.isoeng-
dc.publisher서울대학교 대학원-
dc.subjectPFOA-
dc.subjectvacuum ultraviolet-
dc.subjectsulfite-
dc.subjectiodide-
dc.subjecthydrated electron-
dc.subjectdefluorination-
dc.subject.ddc363.7-
dc.titleReductive decomposition of perfluorooctanoic acid (PFOA) during VUV-based processes-
dc.title.alternativeVUV 기반 공정에서의 perfluorooctanoic acid (PFOA)의 환원적 분해-
dc.typeThesis-
dc.typeDissertation-
dc.contributor.AlternativeAuthorPark Heungjoo-
dc.contributor.department보건대학원 환경보건학과-
dc.description.degree석사-
dc.date.awarded2023-02-
dc.contributor.major환경화학모니터링-
dc.identifier.uciI804:11032-000000174931-
dc.identifier.holdings000000000049▲000000000056▲000000174931▲-
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