WATER RESEARCH
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2024
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IF 11.4
Yihua Chen,Jiaxin Zhu,Hang Ma,Yurong Gu,Tongzhou Liu
Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant posing a risk in environmental persistence, bioaccumulation and biotoxicity. This study was to reach a comprehensive and deeper understanding of PFOS elimination in a UV 254 photolytic treatment with the co-presence of Fe 2+ and nitrilotriacetic acid trisodium salt (NTA). PFOS defluorination was noticeably enhanced in the UV/Fe 2+ -NTA treatment compared with UV/NTA, UV/Fe 2+ and our previously studied UV/Fe 3+ treatments. UV–vis, FTIR, and UPLC/MS-MS results indicated the formation of PFOS-Fe 2+ -NTA complex in PFOS, Fe 2+ and NTA mixture. The transition energy gap of PFOS-Fe 2+ -NTA decreased below the excitation energy supplied by UV 254 irradiation, corresponding with red shift appearing in UV–vis scanning spectrum. This favored intramolecular electron transfer from Fe 2+ -NTA to PFOS under UV 254 irradiation to form electron-accepting PFOS. Molecular electrostatic potential and atom charge distribution analyses suggested electron density rearrangement and perturbation in the perfluorinated carbon chain of electron-accepting PFOS, leading to the decrease in bond dissociation energies. Intermediate products detection suggested the parallel defluorination pathways of PFOS desulfonation, middle carbon chain scission and direct C-F cleavage. NTA exhibited crucial functions in the UV/Fe 2+ -NTA treatment by holding Fe 2+ /Fe 3+ in soluble form as a chelant and favoring water activation to generate hydrated electrons (e aq − ) under UV irradiation as a photosensitizer. Fe 2+ acting as the conduit for electron transfer and the bridge of PFOS anion and NTA was thought functioning best at 200 µM in this study. The degree of UV/Fe 2+ -NTA -synergized PFOS defluorination also depended on e aq − yield and UV 254 photon flux. The structure dependence on the electron transfer process of PFOS and PFOA was explored incorporating molecular structure descriptors. Because of possessing greater potential to acquire electrons or less likeliness to donate its electrons than PFOA, PFOS exhibited faster defluorination kinetics in the published “reduction treatments” than “oxidation” ones. Whereas, PFOA defluorination kinetics were at similar level in both “reduction” and “oxidation” treatments.
研究领域:
环境科学
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化学
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DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2017
·Vol. 7
·期 24
·6000-6012
·
IF 5.773
Wenfeng Han,Chunpeng Zhang,Haili Wang,Shenglan Zhou,Haodong Tang,Luteng Yang,Zhikun Wang
Hydrofluorocarbons (HFCs) which are usually potent greenhouse gases are regulated by the Montreal Protocol and its amendments, especially the recent Kigali Amendment. Dehydrofluorination of HFCs is an efficient route for the conversion of these greenhouse gases to value added and environmentally benign chemicals. Although AlF3 with strong Lewis acidity catalyzes dehydrofluorination, it also favors carbon deposition. MgF2 with weak acidity inhibits coking significantly. Unfortunately, MgF2 sinters dramatically at temperatures below 300 °C leading to the low activity for dehydrofluorination. In the present work, we report that sub-nano MgF2 embedded in carbon fibers and electrospun MgF2 fibers prevent sintering of MgF2 during dehydrofluorination reaction. Via simple and one-step electrospinning and calcination in a N2 (for embedded MgF2) or air (for MgF2 fibers) atmosphere, embedded MgF2 with particle sizes between 3–6 nm and pure MgF2 fibers with diameters of around 100 nm were fabricated. No sintering was observed following reaction at 450 °C. The fine MgF2 particles and MgF2 fibers facilitate the formation of under coordinated Mg species in MgF2 which are the weak acid sites. By embedding MgF2 or fabrication of MgF2 fibers, weak acid sites are increased significantly, while strong acid sites remain almost unchanged. Hence, they show significantly higher reaction rates than MgF2 prepared by precipitation of Mg(CH3COO)2·4H2O with NH4F for the dehydrofluorination of 1,1,1-trifluoroethane (HFC-143a) to VDF (CH2CF2) at 450 °C.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Zhuyu Sun,Dan Geng,Chaojie Zhang,Jiabin Chen,Xuefei Zhou,Yalei Zhang,Qi Zhou,Michael R. Hoffmann
Due to the extremely high stability of perfluorooctane sulfonate (PFOS), effective defluorination is difficult. Previous studies indicated that PFOS can be decomposed under the catalysis of vitamin B12 (VB12) with strong artificial reductants such as Ti(III)-citrate and nZn 0 . In this study, we explored if naturally occurring reductant like sulfide (S 2− ) could initiate the reaction. In S 2− /VB12 system, branched PFOS (br-PFOS) can undergo effective decomposition and defluorination at the temperature of 70 °C and pH greater than 12. The degradation of br-PFOS fits pseudo-first-order kinetic with a rate constant of 0.0984 ± 0.0034 d -1 in the presence of 30 mM Na 2 S and 300 μM VB12, while linear PFOS (L-PFOS) remained stable during 30 d reaction process. UV–Vis spectral characterization indicates that S 2− reduces VB12(Co III ) to Co II , which is able to initiate the reductive defluorination. Based on the product analysis, HF/2F elimination followed by C–C scission is the dominant degradation pathway of br-PFOS instead of stepwise H/F exchange. The primary products include F − and polyfluorinated sulfonates and carboxylates. The degradation of br-PFOS is strongly dependent on temperature due to a relatively high apparent activation energy of 62.86 kJ/mol. Strong alkaline condition can greatly enhance the decomposition efficiency since S 2− is the primary reactive form. This study provides new insights into the VB12-catalyzed defluorination of PFOS and a feasible approach for future natural or engineered remediations of br-PFOS.
研究领域:
环境科学
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化学
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DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2020
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IF 3.612
Jiaqin Lu,Wenfeng Han,Wei Yu,Yongnan Liu,Hong Yang,Bing Liu,Haodong Tang,Ying Li
Aluminum fluoride (AlF 3 ) is a typical catalyst for dehydrofluorination of hydrofluorocarbons (HFCs) to fluoroolefins with high heat of reaction. Consequently, heat supply and sintering are the key challenges for AlF 3 -based catalysts. Herein, SiC with high thermal conductivity and resistance to HF corrosion is suggested as a candidate support of AlF 3 catalyst. The interaction between AlF 3 and SiC leads to uniform distribution of the catalytic phase, and as a result of this, AlF 3 /SiC exhibits high catalytic activity and stability for the dehydrofluorination of 1,1-difluoroethane to vinyl fluoride. This study proposes a novel catalyst support (SiC) for strong endothermic catalytic reactions involving HFCs for the first time to the best of our knowledge.
研究领域:
化学工程
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材料科学
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DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Xing Zhang,Han Wu,Yue Wang,Yafei Wang,Yangyang Deng,Yanping Zhu,Shengsen Zhang,Huub Rijnaarts,Harry Bruning,Junhao Qin,Qingqi Lin,Zhuobiao Ni,Rongliang Qiu
The effectiveness of electrochemical reductive defluorination is impeded by the low environmental concentrations of per- and polyfluoroalkyl substances (PFASs) and the robust nature of C − F bonds. In this work, we investigate the zeolitic imidazolate framework-67 (ZIF-67) as a promising catalyst for PFASs remediation. We show that ZIF-67 hold promise for simultaneous adsorption and reductive defluorination of 2-(trifluoromethyl) acrylic acid (TFMAA). Following a 48-hour treatment, the ZIF-67 modification significantly improves the adsorption of TFMAA onto the cathode surface, achieving removal and defluorination efficiencies of 99.66 % and 97.16 %, respectively (C 0 = 5 mg L −1 , applied voltage of −1.2 V vs. Ag/AgCl). Furthermore, the atomic H*, catalyzed by the Co−N 4 structure, boosts the reductive defluorination of TFMAA through indirect mechanisms, while the nitrogen loss due to carbonization further enhances the catalytic defluorination efficiency. This research presents a novel electrode material for PFASs defluorination and offers mechanistic insights into the defluorination process.
研究领域:
环境科学
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材料科学
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化学工程
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DOI
PubMed
高影响因子
JOURNAL OF FLUORINE CHEMISTRY
·
2024
·
IF 1.7
Xiaoli Wei,Yiwei Sun,Jianhai Jiang,Zhen Wang,Wei Zhang,Bing Liu,Shucheng Wang,Xiaodan Yang,Wanjin Yu,Jianjun Zhang,Wenfeng Han
Al 2 O 3 exhibits high activity for the resource utilization of potent greenhouse gases, hydrofluorocarbons via dehydrofluorination or F/Cl exchange. However, it experiences completely fluorination under corrosive HF environment, leading to thorough fluorination of F-Al-O active site into F-Al-F, accompanied with serious carbon deposition. In this work, we successfully confined Al 2 O 3 in SiC (Al 2 O 3 @SiC) via treating Al 2 O 3 /SiC under high temperatures (>800 °C). The results showed that different with simple loaded Al 2 O 3 (Al 2 O 3 /SiC), during high temperature treatment, reaction between Al 2 O 3 and SiC occurred, leading to the confinement effect. Then, contributed by the interaction, desired F-Al-O species could be stabilized on the surface of SiC. While for Al 2 O 3 /SiC, it thoroughly turned into AlF 3 under identical reactive conditions, leading to inferior stability during CH 3 CHF 2 dehydrofluorination. Furthermore, the reaction rate of 5 %Al 2 O 3 @SiC is nearly up to 4 folds higher than that of traditional AlF 3 . Facilitated by the suitable Lewis acid intensity, less carbon deposition formed on Al 2 O 3 @SiC. Thus, constructing strong interaction between F-Al-O and stable SiC provides a potential strategy to stabilize unstable active centers.
研究领域:
化学工程
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环境科学
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DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2022
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IF 14.224
Yihua Chen,Hang Ma,Jiaxin Zhu,Yurong Gu,Tongzhou Liu
UV/Fe 3+ -facilitated PFOA defluorination was often reported and recognized to proceed through a “ligand-to-metal charge transfer (LMCT)” mechanism in the literatures. Sufficient Fe 3+ supply is important for sustaining the LMCT reaction pathway. In this study, an interesting “excessive defluorination” was observed, even the continuous Fe 3+ supply was cut off, implying a parallel mechanism strengthening PFOA defluorination . Based the results of intermediate products detection, 19 F NMR analysis, and exploration of electron density alternation, transition energy evolution, and bonds characteristics, remarkable electron density perturbation in [PFOA-Fe] 2+ was revealed. This effect was triggered by the complexation between PFOA anion and Fe 3+ , diminishing electron shielding on the perfluorinated carbon chain. Hence, the dissociation energy of C–C bonds was reduced by maximally 53% (C4-C5). Once attacked by high-flux UV 254 photons, the perfluorinated carbon chain underwent scission , and subsequent defluorination was achieved via hydrolysis reactions. This parallel mechanism cooperated with the LMCT mechanism, leading to the observed “excessive defluorination.” The degree of UV/Fe 3+ -synergized PFOA defluorination depended on UV 254 photon flux and Fe 3+ dosage. High UV 254 intensity guaranteed fast defluorination kinetics. A [Fe 3+ ]/[PFOA] molar ratio near 1 showed the best UV/Fe 3+ synergic effect on PFOA defluorination.
研究领域:
环境科学
·
化学
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DOI
PubMed
高影响因子
Heliyon
·
2024
·
IF 3.4
Chenhan Lv,Haixiang Cheng,Rui Fan,Jingyu Sun,Xinghai Liu,Yinghui Ji
Organic fluorine compounds are acute carcinogenic and mutagenic to humans. Photoelectrocatalysis (PEC) treatment is an innovative technology in the field of the removal of fluorine compounds, and thus current research focused on improving stability and catalytic ability of photoanode. In this study, it has been synthesized a rGO/BiOI photocathode for the efficient degradation of 4-Fluoroaniline (4-FA). The physical characterization and photoelectrochemical properties of the photocathode was determined. The results indicate that the PEC treatment with the rGO/BiOI photocathode was more efficient compared with individual processes. During the optimization experiments, the PEC treatment achieved 99.58 % and 72.12 % of 4-FA degradation and defluorination within 1 h. Cyclic stability experiments show that rGO/BiOI photocathode was efficient and stable, which reached 96.91 % and 67.64 % of 4-FA degradation and defluorination after five cycles. Mechanism analysis indicates that the PEC process was based on an electrochemical reaction and photo-induced processes. The degradation product of 4-FA was mainly 2,4-di-t-butylphenol, and trapping experiments indicates that h + is the primary oxidizing species. Therefore, PEC treatment with rGO/BiOI photocathode is a competitive green approach to remove fluorine compounds pollutants and brings new insights into development of PEC treatment.
研究领域:
环境科学
·
材料科学
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DOI
PubMed
高影响因子
CHEMICAL PHYSICS LETTERS
·
2023
·
IF 2.8
Wujian Zhang,Xiangdong Zhou,Hui Sun,Zhenxiang Li,Kangjun Wang,Panpan Zhang,Wenfeng Han,Ying Li,Haodong Tang
The activated alumina with different specific surface areas and different acidity was used to catalyze the dehydrofluorination reaction of CF 3 CH 2 F (HFC-134a). The catalytic performance of the alumina catalysts was rationalized by analyzing the relationship between specific surface area and acidity before and after fluorination. A series of physiochemical techniques, including Scanning Electron Microscope (SEM), X-ray diffraction (XRD), and N 2 physical adsorption (BET), were used to investigate the changes in catalyst structure and surface morphology before and after being tested for the dehydrofluorination reaction. The Al 2 O 3 catalyst prepared from the precipitation method (Al 2 O 3 -P) demonstrated the best stability among all the Al 2 O 3 catalysts. Results from XRD techniques showed that Al 2 O 3 catalysts were fully or partially fluorinated into AlF 3 after the dehydrofluorination reaction. Al 2 O 3 -B catalyst and Al 2 O 3 -S catalyst containing mainly α-AlF 3 deactivate easier than the Al 2 O 3 -P catalyst, which has primarily β-AlF 3 . In addition, it can be concluded the high surface area Al 2 O 3 -P catalyst still has the highest specific surface area and pore size when fluorinated to AlF 3 , while forming the β-AlF 3 crystalline phase. Therefore, it has the optimum catalytic performance for dehydrofluorination of HFC-134a. This provides a new idea for designing alumina catalysts with reasonable structure.
研究领域:
化学工程
·
催化科学
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DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Han Zhang,Yinyin Zhang,Luxiang Zhu,Yanan Liu
The frequent detection of 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) in various environments has raised concerns owing to its comparable or even higher environmental persistence and toxicity than perfluorooctane sulfonate (PFOS). This study investigated the plasma degradation of F-53B for the first time using a water film plasma discharge system. The results revealed that F-53B demonstrated a higher rate constant but similar defluorination compared to PFOS, which could be ascribed to the introduction of the chlorine atom . Successful elimination (94.8–100 %) was attained at F-53B initial concentrations between 0.5 and 10 mg/L, with energy yields varying from 15.1 to 84.5 mg/kWh. The mechanistic exploration suggested that the decomposition of F-53B mainly occurred at the gas-liquid interface, where it directly reacted with reactive species generated by gas discharge . F-53B degradation pathways involving dechlorination , desulfonation , carboxylation , C-O bond cleavage , and stepwise CF 2 elimination were proposed based on the identified byproducts and theoretical calculations. Furthermore, the demonstrated effectiveness in removing F-53B in various coexisting ions and water matrices highlighted the robust anti-interference ability of the treatment process. These findings provide mechanistic insights into the plasma degradation of F-53B, showcasing the potential of plasma processes for eliminating PFAS alternatives in water.
研究领域:
环境科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Jiaxin Zhu,Yihua Chen,Yurong Gu,Hang Ma,Mingyue Hu,Xinlei Gao,Tongzhou Liu
The discharge of widely used per- and poly-fluorinated compounds (PFCs) leads to their environmental prevalence, bioaccumulation and biotoxicity; and attracts researches focusing on their treatment in wastewater. Electrochemical reductive treatment is a promising alternative due to its milder reaction conditions and easy operation. The feasibility of electrochemical reductive decomposition of PFOA using a Rh/Ni cathode was explored. The Rh/Ni cathode was fabricated by coating Rh 3+ on Ni foil through electrodeposition . The Rh coating was primarily elemental and in a Rh(111) crystalline form. PFOA decomposition and defluorination were observed when using the Rh/Ni cathode where DMF was the solvent and the cathode potential was −1.25 V. A hydrodefluorination reaction was considered having occurred. Because possessing d electrons and empty d orbitals, the Rh coating enhanced PFOA adsorption onto the cathode surface and facilitated C F bond activation through Rh···F interactions. Moreover, the Rh(111) crystal helped chemisorb the generated H* and supply it participating in PFOA decomposition. With the continuous interaction of cathode-supplied electrons, C F bond would ultimately dissociate and transform to C H bond by H* substitution. Adding FeCp 2 * as a supporting electrolyte enhanced PFOA decomposition by working as the shuttle facilitating PFOA migration to the cathode surface.
研究领域:
环境科学
·
电化学
·
污染治理
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产品关联
DOI
PubMed
高影响因子
ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Yinghua Xu,Tingjie Ge,Hongxing Ma,Xufen Ding,Xiaoyong Zhang,Qi Liu
Hydrodefluorination (HDF) is the key step in fluoroaromatic pollutant (FAP) degradation, making the search for efficient HDF catalysts and the determination of the corresponding mechanism a matter of great importance. In this study, we developed an efficient HDF catalyst (a Rh-Pd alloy) and investigated the underlying catalytic reaction mechanism , using 4-fluorophenol (4-FP) as a model FAP. Specifically, the rapid aqueous-phase HDF of 4-FP at pH 3 was achieved on a Rh-Pd alloy-modified Ni foam electrode, which was followed by ring hydrogenation (RH) of the HDF product (phenol) to afford cyclohexanone and cyclohexanol . Inductively coupled plasma optical emission spectrometer (ICP-OES) and thermodynamic analyses showed that, in addition to those supplied by the applied current, the electrons involved in the HDF of 4-FP and the RH of phenol were largely provided by the oxidative dissolution of the Ni foam support. Hydrogenation and cyclic voltammetry experiments indicated that the HDF of 4-FP probably follows an indirect mechanism (featuring adsorbed H atoms as the direct reductant) and that the strength of 4-FP adsorption onto the surface of the catalyst significantly influences its HDF activity.
研究领域:
环境科学
·
电化学
·
催化材料
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）