ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2021
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IF 9.028
Zhen Cao,Hao Li,Gregory V. Lowry,Xiaoyang Shi,Xiangcheng Pan,Xinhua Xu,Graeme Henkelman,Jiang Xu
Groundwater contamination by halogenated organic compounds, especially fluorinated ones, threatens freshwater sources globally. Sulfidized nanoscale zero-valent iron (SNZVI), which is demonstrably effective for dechlorination of groundwater contaminants, has not been well explored for defluorination. Here, we show that SNZVI nanoparticles synthesized via a modified post-sulfidation method provide rapid dechlorination (∼1100 μmol m–2 day–1) and relatively fast defluorination (∼6 μmol m–2 day–1) of a halogenated emerging contaminant (florfenicol) under ambient conditions, the fastest rates that have ever been reported for Fe0-based technologies. Batch reactivity experiments, material characterizations, and theoretical calculations indicate that coating S onto the metallic Fe surface provides a highly chemically reactive surface and changes the primary dechlorination pathway from atomic H for nanoscale zero-valent iron (NZVI) to electron transfer for SNZVI. S and Fe sites are responsible for the direct electron transfer and atomic H-mediated reaction, respectively, and β-elimination is the primary defluorination pathway. Notably, the Cl atoms in florfenicol make the surface more chemically reactive for defluorination, either by increasing florfenicol adsorption or by electronic effects. The defluorination rate by SNZVI is ∼132–222 times higher with chlorine attached compared to the absence of chlorine in the molecule. These mechanistic insights could lead to new SNZVI materials for in situ groundwater remediation of fluorinated contaminants.
研究领域:
环境科学
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材料科学
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DOI
PubMed
高影响因子
MATERIALS LETTERS
·
2018
·
IF 2.687
Peng Qu,Xiaolin Liu,Sijing Wang,Chen Xiao,Shanshan Liu
Moderate dehydrofluorinated PVDF (MD PVDF) composed of polyene and untreated PVDF was produced by elimination reaction in polyvinyl pyrrolidone (PVP) and KOH aqueous solution. Dielectric films of MD PVDF were fabricated by solution casting method to study the energy density performance of the polymer. The energy density of MD PVDF was enhanced and the maximum energy density was 10.5 J/cm 3 at 450 kV/mm with an efficiency of 46%. The enhanced energy density was attributed to combined effects of high conductivity of polyene and charges blockage of untreated PVDF. This work may provide a new way to enhance the energy density performance of polymer dielectrics by moderate dehydrofluorination.
研究领域:
材料科学
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能源存储
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DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Min Yang,Xiaolei Zhang,Yicheng Yang,Qiang Liu,Long D. Nghiem,Wenshan Guo,Huu Hao Ngo
This study investigated the degradation of perfluorooctanoic acid (PFOA) on zerovalent iron-laden biochar (BC-ZVI) prepared by carbothermal reduction. Results show that over 99% PFOA can be removed by BC-ZVI in hydrothermal conditions under 240 °C within 6 h. The maximum defluorination rate of 63.2% was achieved after 192 h, and this outcome was significantly better than biochar (BC) and zero-valent iron (ZVI) alone. The short-chain perfluorinated compounds (PFCs) and perfluoroheptanal were detected in the liquid phase after degradation, suggesting that the degradation of PFOAs by BC-ZVI followed the Kobel decarboxylation process. XRD and SEM-EDS analyses strongly suggested that carbothermal reduction could avoid the agglomeration of ZVI loaded onto biochar, which helped make the PFOA degradation more efficient. The frontier molecular orbital theory calculated by density functional theory revealed there were two possibilities for ZVI loading on BC (edged or internal loading), while the edge loaded ZVI had a greater tendency to provide electrons for the defluorination of PFOA than internally loaded ZVI.
研究领域:
环境科学
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化学工程
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DOI
PubMed
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Yiwei Sun,Xiaoli Wei,Wei Zhang,Zhen Wang,Jianhai Jiang,Fangcao Liu,Bing Liu,Wenfeng Han
Conversion of potent greenhouse gases, hydrofluorocarbons (HFCs), to value-added hydrofluoroolefins (HFOs) is of great importance. AlF3 catalysts play a major role in this process. Formation and maintenance under coordinated Al are the key to prepare efficient catalysts. Herein, carbon interacted AlF3 nanoclusters catalyst (AlF3–SAPO-5) was effectively achieved with SAPO-5 molecular sieves as precursors via pyrolysis followed by in situ fluorination. This process results in a strong interaction between the carbonaceous material and active aluminum (Al) species. The results show that AlF3–SAPO-5 possesses both high activity and thermal stability. For 1,1-difluoroethane (HFC-152a) dehydrofluorination, the conversion can reach up to 95% at a reaction temperature of 350 °C. The reaction rate is almost 4 times higher than that of AlF3 prepared by traditional pyrolysis (AlF3-py). It implies that the confinement effect contributes to the formation of AlF3 nanoclusters with abundant 4- and 5-coordinated Al species stabilized by the F–Al–O–C structure. In addition, the carbon-interacted AlF3 nanoclusters exhibit superb sintering resistance. Given its fantastic activity and thermal stability, the carbon-interacted AlF3 nanoclusters show great potential for the catalytic dehydrofluorination of fluorinated alkanes.
研究领域:
化学工程
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材料科学
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催化反应
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DOI
高影响因子
Environmental Technology & Innovation
·
2024
·
IF 6.7
Yongjia Lei,Hongyu Zeng,Ravi Naidu,Dong Tian,Li Zhao,Mei Huang,Jinsong He,Jianmei Zou,Shihuai Deng,Li Sun,Fei Shen
Due to the synergistic contribution, dual-frequency ultrasound can significantly enhance the degradation of organic contaminants, but the effects of different frequency combinations have not been clarified and need to be explored. In this study, several frequency combinations were designed firstly both in experimental exploration and numerical simulation within the dual-frequency ultrasound coupling persulfate (PS) system to investigate the effect of frequency combinations on the degradation of perfluorooctanoic acid (PFOA). The monitoring parameters included the defluorination percentage and the simulated maximum expansion ratio ( R max / R 0 ). The simulated maximum expansion ratios in different frequency combinations showed a high correlation with their defluorination results, indicating that the discrepancy in defluorination effects of different frequency combinations was mostly attributed to their various maximum expansion ratios. Additionally, various maximum expansion ratios could result in different maximum solution temperatures, and the increase in temperature was found positive for PFOA defluorination in this study. In addition, the synergistic parameters that affected the maximum expansion ratio were analyzed, including the phase difference, frequency ratio, and frequency value. The obtained results showed that the maximum expansion ratio varied with different phase differences, and the frequency ratio could affect the variation trend. For the same fundamental frequency, the larger the frequency ratio, the smaller the maximum expansion ratio. Under the same phase difference and frequency ratio, the larger the frequency value, the lower the cavitation.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
CHEMOSPHERE
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2022
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IF 8.943
Yuqi Zhou,Hanqing Lv,Jin Lin,Tianyu Lv,Nan Wang,Heqing Tang,Lihua Zhu
This work reports a mechanochemical (MC) method for complete defluorination of perfluorooctanoic acid (PFOA) by using Al and Al 2 O 3 as milling agents. Both the Al/Al 2 O 3 molar ratio ( n Al / n Al 2 O 3 ) and the pre-thermal treatment of Al 2 O 3 strongly influenced the defluorination of PFOA. When commercial γ -Al 2 O 3 was pre-treated at 1200 °C, the use of Al and heat-treated γ -Al 2 O 3 with n Al / n Al 2 O 3 of 1: 1 led to PFOA defluorination of 100% after ball milling for 26 min at 350 rpm, being much higher than those (8.3%–58.1%) for using singlet milling agents or binary milling agents containing γ -Al 2 O 3 pre-heated at temperatures lower than 700 °C. It was clarified that the carboxylate-mediated adsorption of PFOA on Al 2 O 3 was essential for the MC decarboxylation as a degradation initiation step, and the in-situ generated electron on milled Al consequently caused the reductive dissociation of C–F bonds in the decarboxylation intermediate. A larger n Al / n Al 2 O 3 increased the in-situ electron generation rate ( r e ), and a higher heat-treatment temperature decreased OH − /H 2 O adsorbed on Al 2 O 3 to low the PFOA decarboxylation rate ( r dec ). The r e / r dec ratio determined defluorination pathways, and the percentage of the defluorination of PFOA in its total degradation including the generation of any degradation intermediates increased linearly with increasing r e / r dec .
研究领域:
环境科学
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化学工程
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2023
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IF 7.7
Yuancai Lv,Shiyu He,Shuting Liu,Zhendong Yu,Yanting Jiang,Yihui Hu,Yifan Liu,Chunxiang Lin,Xiaoxia Ye,Guifang Yang,Minghua Liu
Doping polymetals on Fe-based catalysts is proved to be an effective way to improve the performance on activating persulfate. In this paper, a highly efficient persulfate activation catalyst (FeCo@MoS 2 ) was successfully synthesized by introducing MoS 2 onto the surface of FeCo nanoboxes. During the activation of PMS the introduced of MoS 2 effectively promoted the formation of free radicals (∙OH, SO 4 · - ), 1 O 2 and Fe(IV). Due to the synergistic effects between Mo and Fe, FeCo@MoS 2 has better catalytic activity (2.01 times larger of defluorination efficiency and 3.91 times larger of the apparent rate constant ( k obs )) than FeCo. Under the optimal conditions (catalyst dosage of 0.2 g L −1 , PMS dosage of 1.0 g L −1 and initial pH 4.0), the perfluorooctanoic acid (PFOA, 10 mg L −1 ) could be degraded in 60 min, with 90.26 ± 2.64% of the defluorination efficiency. The LC- MS results showed that under the attack of free radicals (∙OH, SO 4 · - ), 1 O 2 and Fe(IV), the PFOA underwent step-by-step defluorination process. In addition, the ECOSAR results showed that during the whole degradation of PFOA in FeCo@MoS 2 /PMS system, no highly toxic intermediates was accumulated, suggesting a green degradation process. This work showed new ideas and strategies for studying the influence of polymetallic doping on the catalytic process of PMS multiphase catalytic system.
研究领域:
环境科学
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催化化学
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产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2024
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IF 12.2
Xun Liu,Yufei Shu,Yu Pan,Guoshen Zeng,Meng Zhang,Chaoqun Zhu,Youmei Xu,Aling Wan,Mengxia Wang,Qi Han,Bei Liu,Zhongying Wang
The persistence and ecological impact of per- and poly-fluoroalkyl substances (PFAS) in water sources necessitate effective and energy-efficient treatment solutions. This study introduces a novel approach using cerium dioxide (CeO 2 ) electrodes enhanced with oxygen vacancy (O v ) to catalyze the defluorination of PFAS. By leveraging the unique affinity between cerium and fluorine-containing species, our approach enables adsorptive preconcentration and catalytic degradation at low oxidation potentials (1.37 V vs. SHE). Demonstrating high removal and defluorination efficiencies of perfluorooctanoic acid (PFOA) at 94.0% and 73.0%, respectively, our approach also proves effective in the environmental matrix. It minimizes the impacts of co-existing natural organic matter and chloride ions, crucial benefits of operating at lower oxidation potentials. The role of O v in CeO 2 is validated by both experimental results and density functional theory modeling, demonstrating that these sites can activate the C–F bond and substantially reduce the energy barriers for defluorination. Consequently, our CeO 2 -based method not only achieves defluorination efficiencies comparable to more energy-intensive techniques but does so while requiring less than 0.62 kWh/m 3 per order. This positions our approach as a promising, cost-effective alternative for the remediation of PFAS-contaminated waters, emphasizing its relevance and effectiveness in environmental remediation scenarios.
研究领域:
环境科学
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材料科学
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产品关联
DOI
PubMed
高影响因子
WATER ENVIRONMENT RESEARCH
·
2020
·Vol. 93
·期 3
·455-463
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IF 1.369
Yuanhao Li,Qiufeng Lin,Cong Li,Zijian Weiguo,Luo Xu,Kejia Zhang
Perfluorooctanoic acid (PFOA) is one kind of persistent organic pollutants that is often detected in water. In recent years, the effective degradation technologies of PFOA have attracted widespread attentions. Thus, in this study, the defluorination efficiency of PFOA in different systems (i.e., ultraviolet (UV), vacuum ultraviolet (VUV), vacuum ultraviolet/persulfate (VUV/PS) and vacuum ultraviolet/residual chlorine (VUV/RC)) was evaluated. Moreover, the different impact factors (i.e., the initial concentrations of persulfate and PFOA, temperature, anions, and initial pH values) on PFOA degradation by VUV/PS system were investigated. The results showed that VUV system was more effective than UV system for PFOA defluorination. VUV system combined with persulfate would further enhance the defluorination efficiency while residual chlorine would decrease it. In VUV/PS system, the defluorination efficiency of PFOA was the best as the molar ratio of PFOA and persulfate at 1:60. Moreover, higher temperature, lower initial PFOA concentration, and acid condition were favorable for the defluorination of PFOA. Under the different influence factors, the defluorination efficiency of PFOA fitted well to the first-order reaction kinetic model. When the temperature was range from 20°C to 40°C, the value of activation energy was 8.73 kJ/mol. Besides, the inhibition effect of three kinds of anions on PFOA defluorination followed the order: > Cl − > . Practitioner points The defluorination efficiency of perfluorooctanoic acid (PFOA) in water by different VUV systems was compared. VUV system is more effective than UV system for PFOA defluorination. Persulfate will enhance the defluorination efficiency by VUV system. Hypochlorite will decrease the defluorination efficiency by VUV system.
研究领域:
环境科学
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水处理
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污染物降解
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产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2019
·
IF 7.149
Nan Wang,Hanqing Lv,Yuqi Zhou,Lihua Zhu,Yue Hu,Tetsuro Majima,Heqing Tang
Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that has received concerns worldwide due to its extreme resistance to conventional degradation. A mechanochemical (MC) method was developed for complete degradation of PFOA by using alumina (Al2O3) and potassium persulfate (PS) as comilling agents. After ball milling for 2 h, the MC treatment using Al2O3 or PS caused conversion of PFOA to either 1-H-1-perfluoroheptene or dimers with a defluorination efficiency lower than 20%, but that using both Al2O3 and PS caused degradation of PFOA with a defluorination of 100% and a mineralization of 98%. This method also caused complete defluorination of other C3∼C6 homologues of PFOA. The complete defluorination of PFOA attributes to Al2O3 and PS led to the weakening of the C–F bond in PFOA and the generation of hydroxyl radical (•OH), respectively. During the MC degradation, Al2O3 strongly anchors PFOA through COO––Al coordination and in situ formed from Lewis-base interaction and PS through hydrogen bond. Meanwhile, mechanical effects induce the homolytic cleavage of PS to produce SO4•–, which reacts with OH group of Al2O3 to generate •OH. The degradation of PFOA is initiated by decarboxylation as a result of weakened C–COO– due to Al3+ coordination. The subsequent addition of •OH, elimination of HF, and reaction with water induce the stepwise removal of all carboxyl groups and F atoms as CO2 and F–, respectively. Thus, complete defluorination and mineralization are achieved.
研究领域:
环境科学
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化学工程
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污染物降解
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产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Yongjia Lei,Lirong Zhao,Cheng Fang,Ravi Naidu,Dong Tian,Li Zhao,Mei Huang,Jinsong He,Zhang Cheng,Zhenxing Zeng,Jianmei Zou,Xiaohong Zhang,Shihuai Deng,Fei Shen
A novel enhanced defluorination of perfluorooctanoic acids (PFOA) by surfactant-assisted ultrasound (US) coupling persulfate (PS) was proposed in this study. Instead of adding the surfactant into the PFOA solution directly, the promoted defluorination was obtained by adding the surfactant to the US bath outside of the PFOA reactor. In this situation, the effects of the critical micelle concentration (CMC), concentration and type of the surfactant, the US frequency and the pH of the US bath liquid on the PFOA defluorination were investigated. The results demonstrated that the PFOA defluorination at low-frequency levels (25 kHz-59 kHz) was facilitated by raising US frequency. Besides, the addition of three surfactants (Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) all increased the PFOA defluorination by Triton X-100 > CTAB > SDS , which is opposed to their CMC (Triton X-100: 0.28 mM＜CTAB: 1.07 mM＜SDS: 7.69 mM). Rising the surfactant concentration would not enhance the defluorination, the best one was obtained at its CMC. Moreover, changing the pH of the US bath liquid by adding acid or alkaline solution inhibited the defluorination, which might be attributed to acid or base causing damage to the chemical properties or physical structure of surfactant (certified by the SEM tests). Additionally, the mechanism of enhanced PFOA defluorination was examined by electron paramagnetic resonance analysis, which proved that adding surfactant facilitated the generation of the radicals (·OH and S O 4 ∙ - ), as well as the radicals’ amount increased over time during 60 min. Finally, the inhibited defluorination of adding surfactant directly to the PFOA solution was studied by the SEM analysis, the results demonstrated that adsorption and wrapping between surfactant micelles and PFOA reduced the contact between PFOA and radicals and affected the surfactant effect on the surface tension.
研究领域:
环境科学
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化学工程
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分析化学
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 103
·84856-84864
·
IF 3.84
Qianchi Ma,Lei Liu,Wei Cui,Ruifeng Li,Tingting Song,Zhaojie Cui
Model aqueous solutions of perfluorooctanoic acid (PFOA, 100 mg L−1) were electro-oxidized in a homemade container. The electrocatalytic behavior and anodic performance of Ti/SnO2–Sb/Yb–PbO2, Ti/SnO2–Sb–PbO2 and Ti/SnO2–Sb–Yb anodes in sodium electrolytes were compared. The SnO2–Sb/Yb–PbO2 anode demonstrated better electrocatalytic performance compared with the SnO2–Sb–PbO2 and SnO2–Sb–Yb electrodes in terms of both degradation and defluorination. Then a systematic experimental study was designed as follows to analyze the influencing factors: initial concentration of PFOA (10 mg L−1 to 200 mg L−1), current density (1 mA cm−2 to 40 mA cm−2), initial pH value (3 to 11) and electrode distance (5 mm to 20 mm). After a 150 min electrolysis, the optimum reaction conditions were obtained and the degradation and defluorination ratios reached 95.11 ± 3.9% and 75.7 ± 2.8%, respectively. Under the optimum conditions, the degradation of PFOA followed pseudo-first-order kinetics (0.0193 min−1) and the degradation half-life was 35.9 min. The produced F− was measured using a fluoride ion selective electrode, whereas the intermediate PFCAs with short-chain lengths were measured using HPLC-MS. A detailed degradation pathway was proposed in this study by analyzing the intermediates and the recovery of fluoride.
研究领域:
环境科学
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化学工程
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分析化学
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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）