https://scholars.lib.ntu.edu.tw/handle/123456789/598503
Title: | New insight into PFOS transformation pathways and the associated competitive inhibition with other perfluoroalkyl acids via photoelectrochemical processes using GOTiO2 film photoelectrodes | Authors: | Yang J.-S Lai W.W.-P ANGELA YU-CHEN LIN |
Keywords: | Competitive inhibition;PFOS;Photoelectrochemical;Reactive oxygen species, Byproducts and reaction pathways;Carboxylation;Chain length;Chlorine compounds;Electrodes;Electrolytes;Energy gap;Free radical reactions;Graphene;Oxygen;Rate constants;Sodium compounds;Titanium dioxide;Oxygen reaction;Perfluoroalkyl acids;Perfluorooctane sulfonates;Photoelectrochemical system;Photoelectrochemicals;Photoelectrode;Reaction pathways;Reactive oxygen species;Reactive oxygen species, byproduct and reaction pathway;Degradation;aldehyde;carbon;electrolyte;graphene oxide;hydroxyl radical;perfluorooctanesulfonic acid;reactive oxygen metabolite;sodium perchlorate;sulfurous acid;superoxide;alkanesulfonic acid;carboxylic acid;fluorocarbon;biotransformation;chemical composition;chemical compound;detection method;electrochemical method;inhibition;oxidation;surface area;transformation;Article;comparative study;competitive inhibition;controlled study;current density;decarboxylation;decomposition;defluorination;degradation;electron transport;first order rate constant;fluorination;hydroxylation;reaction analysis;reaction time;sulfonation;environmental monitoring;Missouri;Novelty;United States;Alkanesulfonic Acids;Carboxylic Acids;Environmental Monitoring;Fluorocarbons | Issue Date: | 2021 | Journal Volume: | 207 | Source: | Water Research | Abstract: | The global distribution and environmental persistence of perfluoroalkyl acids (PFAAs) has been considered a critical environmental concern. In this work, we successfully fabricated a graphene oxide-titanium dioxide (GOTiO2) photoelectrode for perfluorooctane sulfonate (PFOS) degradation in a photoelectrochemical (PEC) system. The results reveal that a 5 wt.% GOTiO2 anode possesses the optimal PEC performance, with a band gap (Eg) of 2.42 eV, specific surface area (SBET) of 72.6 m2 g?1 and specific capacitance (Cs) of 4.63 mF cm?2. In the PEC system, PFOS can be efficiently removed within 4 h of reaction time, with a pseudo-first-order rate constant of 0.0124 min?1, under the optimized conditions of current density = 20 mA cm?2, electrode distance = 5 mm, solution pH = 5.64, [PFOS]0= 0.5 ?M and NaClO4 electrolyte concentration = 50 mM. The electron transfer pathway, hydroxyl radicals and superoxide radicals are all responsible for PFOS decomposition/transformation. New degradation pathways were identified; a total of 25 PFOS byproducts are reported in this work; and perfluoroalkane sulfonates (PFSAs), perfluorinated aldehydes (PFALs) and hydrofluorocarbons (HFCs) were identified for the first time. PFOS degradation involves the desulfonation pathway as the first step, followed by oxidation and subsequent defluorination, decarboxylation, decarbonylation, sulfonation, defluorination and hydroxylation. The results from this work also show that the reactivity of PFAAs is related to their carbon chain length, with shorter-chain PFAAs exhibiting a lower degradation rate. In a PFAA mixture, a decline in the degradation rate was observed for the shorter-chain-length PFAAs, suggesting stronger competitive inhibition and indicating stronger environmental recalcitrance during the treatment process. Novelty statement: Although many efforts have been made to identify perfluorooctane sulfonate (PFOS) degradation byproducts, previous studies were only able to identify byproducts that are related to perfluorinated carboxylic acids (PFCAs). This is the first study to elucidate the new PFOS degradation pathway; furthermore, this is the first report to identify byproducts containing sulfonate groups (perfluoroalkane sulfonates, PFSAs), aldehyde groups (perfluorinated aldehydes, PFALs), and hydrofluorocarbons (HFCs). This study further systematically explores how perfluoroalkyl acid (PFAA) degradation may be affected in the mixture system: shorter-chain-length PFAAs suffer stronger competitive inhibition in the photoelectrochemical (PEC) system. By utilizing the graphene oxide-titanium dioxide (GOTiO2) photoelectrode fabricated in this work, PFOS can be successfully decomposed during the PEC process for the first time. ? 2021 |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118255571&doi=10.1016%2fj.watres.2021.117805&partnerID=40&md5=82159277cd24571e29e4c22b144e2075 https://scholars.lib.ntu.edu.tw/handle/123456789/598503 |
ISSN: | 00431354 | DOI: | 10.1016/j.watres.2021.117805 |
Appears in Collections: | 環境工程學研究所 |
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