ACS ES&T Water
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2022
·
IF 0
Xiaofeng Fang,Ruo Li,Ziyi Zhang,Xingran Zhang,Fang Li,Yanbiao Liu
Excellent perm-selectivity and fouling resistance are highly desirable for membrane separation in water treatment. Electrically conductive membranes have been recognized as an effective means for overcoming the permeability–selectivity trade off and enhancing the antifouling capability. However, the facile and controllable fabrication of conductive membranes with good flexibility, high conductivity, and stable separation performance remains a challenge. Herein, a novel conductive poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membrane with a thin silver nanoparticle (Ag NP) coating layer was developed via nonsolvent phase separation and green in situ reduction methods. Especially, the tannic acid/Fe3+ (TA/Fe) complex and carbon nanotube (CNT) were first blended into a PVDF UF membrane. The thin Ag NP coating layer was then in situ formed and firmly fixed on the membrane with TA to produce a conductive PVDF/TA-Ag composite membrane. The introduced Ag NP coating layer not only narrowed the pore size but also increased the electrical conductivity of the PVDF/TA membrane, which resulted in an enhanced electrostatic repulsion and remarkable humic acid (HA) rejection. The optimal membrane (i.e., PVDF/TA-Ag12) achieved an improved HA solution flux of 265 LMH/bar and an HA rejection of 97% under −2 V applied voltage, which are 2 times and 1.7 times higher than those of the uncharged membrane, respectively. Moreover, the PVDF/TA-Ag12 membrane exhibited a superior antifouling performance under an external electrical field. Meanwhile, the electrochemical reduction of Ag+ to Ag0 on the membrane matrix can effectually avoid the Ag NP leaching, keeping the stability of the separation performance. These findings provide an alternative and cost-effective method for the development of polymer conductive membranes to enhance pollutant rejection and mitigate membrane fouling.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Jingtong Yu,Dongmin Yue,De Sun,Bingbing Li,Yanxia Ge,Yuanhang Lin
Solar-driven photothermal conversion vacuum membrane distillation (SVMD) becomes an energy-efficient water treatment thanks to the thermal localization of photothermal membranes. Membrane photothermal activity and distillation performance are essential for creating photothermal composite membranes. Herein, a CuO/CF-PVDF photothermal composite membrane has been designed with flower-like copper oxide (CuO/CF) photothermal active-layer and polyvinylidene fluoride (PVDF) microporous hydrophobic separation layer. Firstly, the flower-like CuO/CF layer with the light trapping was obtained by in-situ surface oxidation on the copper foam (CF) surface. Then, by the NIPS method, PVDF microporous hydrophobic layer was scraped on one side of the CuO/CF photothermal active-layer and firmly fixed on the porous surface of CuO/CF layer by anchoring effect. The light trap consisted of CuO micron flowers and Cu(OH) 2 nanowires. The gaps among the petals increased the light refractive rate and absorption area, thus enhancing the photothermal performance of the CuO/CF. Under 1 kW‧m −2 solar irradiation, the absorption rate reached up to 95 %, and the photothermal conversion efficiency achieved 94 %. For the SVMD process, compared to current research, the CuO/CF-PVDF achieved the permeate flux of 3.34 kg‧m −2 ‧h −1 and energy efficiency of 88 % under average feed temperature. Overall, the CuO/CF-PVDF membrane has promising potential for desalination by fully using sustainable energy.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 47
·32482-32492
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IF 3.3
Shuo Zheng,Xuanchen Zhao,Junhao Xie,Shulin Sun
Polymer-based dielectric materials have been used in film capacitors due to their rapid charge–discharge rate, lightness, and low cost. Nevertheless, the energy storage properties of these dielectric films were limited by their weak polarization ability and low discharge energy density. Herein, the solution casting method was used to prepare all-organic crosslinked composite films using linear methyl methacrylate-co-glycidyl methacrylate (MG) as the matrix and ferroelectric poly(vinylidene fluoride) (PVDF) as the organic filler. The crosslinked MG networks can enhance the breakdown strength, restrain dielectric loss, and keep high discharge efficiency. What's more, the presence of PVDF can compensate for the low electrical displacement, improve the permittivity, and overcome the brittleness of the crosslinked films. The optimal all-organic crosslinked dielectric film exhibited an ultrahigh breakdown strength of 800 MV m−1 and a high efficiency of 77.4%. The maximum energy density of the composite film reached up to 12.1 J cm−3, which was nearly 120% higher than the energy density of 5.6 J cm−3 of the pure MG film. The enhancement in energy storage properties is ascribed to the synergistic effects of chemical crosslinking and hydrogen bonding. This study offers a feasible method for all-organic polymer films to fabricate energy storage equipment.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Wenliang Feng,Jing Zhang,Abdulmalik Yusuf,Xiang Ao,Dongfeng Shi,Vinodkumar Etacheri,De-Yi Wang
The practical application of sodium-ion hybrid capacitors is limited by their low energy densities resulted from the kinetics mismatch between cathodes and anodes, and the fire safety related to the flammable electrolyte-separator system. Hence, we report a rational design of metal–organic frameworks (MOFs, UiO-66) modified PVDF-HFP separator. High tensile strength and dimensional thermal stability of the separator reduce the risk of electrode short circuit caused by the separator deformation. MCC test demonstrates a reduction of 75% in peak heat release rate (pHRR), indicating an enhanced fire-resistant property of the separator. This is due to the transformation of UiO-66 into ZrO 2 accompanied by the consumption of oxygen and the formation of the barrier char that suppresses further heat release. Quasi-solid-state electrolyte prepared based on this separator presents an enhanced ionic conductivity of 2.44 mS cm −1 and Na-ion transference number of 0.55, which are related to the high porosity (>70%) and electrolyte uptake (~320%) of the separator. Moreover, the open metal sites of UiO-66 can capture PF 6 – and consequently liberate the Na + for faster migration, thus reducing the kinetics mismatch between cathodes and anodes. Such multifunctional separator enables the quasi-solid-state Na-ion hybrid capacitor to achieve high energy density (182 Wh kg −1 @31 W kg −1 ) and power density (5280 W kg −1 @22 Wh kg −1 ), as well as excellent cyclic stability (10,000 cycles @1000 mA g −1 ).
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JOURNAL OF ELECTRONIC MATERIALS
·
2021
·Vol. 50
·期 4
·2182-2189
·
IF 1.938
Feng Yefeng,Zhao Xiaomiao,Chen Peiyao,Bo Maolin,Deng Qihuang,Zhao Anning,Fu Junjie
High-dielectric-constant (high- k ) polymer–ceramic composites with low-level dielectric loss are expected to enable excellent energy storage. However, high conductivity and high dielectric loss often occur simultaneously with high dielectric constant. To obtain a high dielectric constant but with low conductivity and low dielectric loss, in this work, we studied the ternary polyvinylidene fluoride (PVDF)/La 2 TiO 5 /V 2 C dielectric composite system, which takes advantage of the synergistic effect between the high content (0 wt.% to 40 wt.%) of pseudo-perovskite filler La 2 TiO 5 and the low content (2 wt.%) of highly conductive two-dimensional filler V 2 C. Comparisons with the binary PVDF/La 2 TiO 5 composite system revealed that the ternary PVDF/La 2 TiO 5 /V 2 C composite dielectric system enabled balance and optimization of the comprehensive electrical properties of the composite material. Significantly elevated permittivity as well as depressed low-level dielectric loss were obtained in the ternary composites. The optimized ternary composite with 40 wt.% La 2 TiO 5 and 2 wt.% V 2 C exhibited high dielectric constant of 47 and low dielectric loss of 0.17 at 1 kHz. This work might enable facile fabrication of promising composite dielectric materials based on this excellent synergetic filler strategy.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Hui Chen,YaFei Hou,ZhiJie Wu,Peng Du,LaiHui Luo,WeiPing Li
The progress of dielectric capacitors with superior energy storage density ( U e ) has drawn widely attentions in recent years. However, most studies improve the U e at the cost of their energy storage efficiency ( η ), which greatly limits their practical applications. In this study, a nanocomposite film based on the nickel hydroxide (Ni(OH) 2 ) and the polymethylmethacrylate and polyvinylidene fluoride blend polymer (PMMA/PVDF) is designed and prepared ( x vol%-Ni(OH) 2 -PMMA/PVDF). It has been found that introducing Ni(OH) 2 and PMMA into ferroelectric PVDF is not only able to improve the dielectric constant and breakdown field, but also able to suppress the dielectric loss and leakage current density of nanocomposite films, leading to enhanced U e and η simultaneously. Furthermore, the finite element simulation was adopted to demonstrate the mechanism of compatible improvement on the dielectric constant and breakdown field in the nanocomposite films, respectively. An excellent U e of 14.5 J/cm 3 and η of 71.7% are realized in the 3 vol%-Ni(OH) 2 -PMMA/PVDF nanocomposite film at 445 MV/m. The significantly improved U e in this composite is 181% higher than that of the pristine PMMA film and 250% higher than that of the pure PVDF film. Thus, this study might provide a new path to design the nanocomposite films with high U e and η simultaneously.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Na Li,Huai-duo Chen,Yong-ze Lu,Ming-chao Zhu,Zhao-xia Hu,Shou-wen Chen,Raymond Jianxiong Zeng
In recent years, nanoscale zero-valent iron (nZVI) has been considered an appealing alternative for halogenated organic compound removal for its advantages, such as its high activity. However, easy aggregation limits nZVI activity. In this study, functional nZVI-modified PVDF membranes (nZVI@PVDF membranes) were successfully prepared by a simple and easy-to-follow filter-press coating method and was applied in the ultrafiltration process to treat 2-chlorophenol (2-cp) wastewater. Scanning electron microscopy showed that nZVI particles were relatively uniformly distributed on the membrane surface and formed a fluffy and porous space-stacked structure. 2-cp ultrafiltration degradation results illustrated that nZVI@PVDF membranes revealed good 2-cp removal efficiencies ranged from 56.06% to74.62%. These 2-cp removal efficiencies were higher than those for Fe supported on powder materials and were relatively comparable to those for nZVI composite membranes prepared by complex methods (e.g., blend spinning and cross-linking methods). Furthermore, the 2-cp degradation efficiencies by nZVI@PVDF membranes were not affected much in the presence of natural organic matter and different ions, demonstrating a robust anti-interference ability of nZVI@PVDF membrane. The mechanism underlying its robust performance likely resulted from that nZVI was uniformly distributed and loaded layer by layer on the PVDF membrane surface with high loading capacity, which guaranteed high nZVI activity, layer-layer interception of pollutants and complete reaction between nZVI and pollutants. These findings provide key insights into how nZVI@PVDF membranes could be integrated into the treatment of wastewater containing refractory pollutants.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 27
·期 36
·45605-45617
·
IF 3.056
Zhou Anran,Wang Yonglei,Sun Shaohua,Xin Xiaodong,Wang Mingquan,Zhao Qinghua,Zhu Huanhuan,Jia Ruibao
The addition of Fe 3+ to TiO 2 is one of the effective methods to inhibit the recombination of photogenerated electrons and holes and thus improve the photocatalytic activity of TiO 2 . The effect of PVDF-PVP-TiO 2 -FeCl 3 (PPTFe) membrane filtration-photocatalytic system on the removal of trace concentration of sulfadiazine (SD) in water was evaluated. A two-factor four-level experiment was established to optimize 16 self-made modified membranes. The optimal membrane was then characterized in seven tests (SEM, EDS, membrane pure water flux, contact angle, porosity, mean pore size, ATR-FTIR), resulting in the optimal ratio (PPTFe membrane with 1.2 wt%TiO 2 and 0.8 wt%FeCl 3 ). Compared with the original membrane, the pore number, pore size, permeability, and hydrophilicity of the PPTFe membrane were all enhanced. The removal efficiency (92.63%) of SD by PPTFe membrane filtration-photocatalysis system was investigated. The reaction rate (0.0214 min −1 ) of the removal SD of the system was determined according to the pseudo-first-order kinetic model. The removal performance of membrane type, pH, and water quality parameters (Cl − , SO 4 2− , NO 3 − , HA) on PPTFe membrane filtration-photocatalytic system were also made a deep inquiry. The results reflected that acidic conditions (pH = 3) were beneficial to SD removal, the presence of Cl − , SO 4 2− , and HA could inhibit SD removal, while the existence of NO 3 − was unaffected. Furthermore, the removal rate of SD in the actual water body was displayed well in this system. Finally, the possible photocatalytic degradation mechanism was proposed. Graphical abstract
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JOURNAL OF MEMBRANE SCIENCE
·
2020
·
IF 7.183
Zhenghua Guo,Yi Yang,Shang Xiang,Xi Du,Zhenyu Cui,Benqiao He,Hong Wang,Jianxin Li,Tao Jiang
In this work, poly(vinylidene fluoride) (PVDF) flat membrane was prepared via “In-situ template-TIPS” technology using poly(vinylpyrrolidone) (PVP) as template. The membrane formation mechanism and microstructure evolution of this method were expounded for the first time. The effect of PVP content on the crystallization behavior of the dope, the microstructure, the crystallization behavior and the permeability of the membrane was investigated in detail. Interestingly, the solidification of PVP from the diluent via air-cooling at room temperature not only hindered the PVDF crystallization, but also the growth of PVP led to the formation of porous surface and eliminated the thick and dense skin layer, and thus formed the inter-connected structure and higher porosity (The maximum porosity is 88.9%). The maximum pure water flux reached as high as 3420 L m −2 h −1 . The membrane also indicated an excellent performance in rejection of bacteria and separation of “petroleum ether/water” emulsion (nearly 100%). The α crystal phase was formed for the membrane by air-cooling at room temperature. The non-isothermal crystallization kinetics revealed that PVP can act as a heterogeneous nucleating agent for PVDF crystallization and hindered the growth of PVDF crystal in three-dimension. The research presented a novel and simple idea for tailoring the microstructure of membrane via TIPS process.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2020
·
IF 5.774
Bin Jiang,Kai Cheng,Na Zhang,Na Yang,Luhong Zhang,Yongli Sun
Herein, hydrophobic PVDF membranes were facilely transformed into highly hydrophilic and underwater superoleophobic ones via one-step dip-coating in tannic acid (TA)/sodium periodate (NaIO 4 )-mixed solution. The employment of NaIO 4 could not only facilitate TA oxidation and deposition, but also introduce abundant hydrophilic carboxyl groups on membrane surface. Consequently, compared with the pristine PVDF membrane, the modified membrane showed much higher hydrophilicity and underwater oleophobicity with water contact angle decreasing from 121° to 32°, oil contact angle increasing from 116° to 162° and a tilt angle of just 2°. In contrast to the two-step modification (deposition of TA followed by post-oxidation by NaIO 4 ), our approach endowed the membrane with dramatically improved permeability (>2400 LMH/bar) and oil rejection (>98%) when dealing with different types of oil-in-water emulsions. Additionally, the membrane displayed excellent antifouling performance with flux recovery ratios of above 95% and favorable reusability after 5-cycle filtration tests. Moreover, the membrane possessed a stable TA coating even being subjected to harsh pH solutions or sonication. This work provides a simple, robust and cost-effective strategy for membrane modification.
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高影响因子
Journal of Physical Chemistry C
·
2020
·
IF 4.189
Yefeng Feng,Furong Zhou,Maolin Bo,Yuehao Huang,Qihuang Deng,Cheng Peng
High dielectric constant and breakdown strength are crucial for high-energy-density polymer/ceramic composites. Anatase-TiO2 with low dielectric constant and V2C MXene with high work function are not satisfactory fillers. In the present work, V2C–TiO2 hybrid filler was in situ synthesized, followed by fabricating poly(vinylidene fluoride) (PVDF)/V2C–TiO2 composites via solution cast. Compared with PVDF/TiO2 and PVDF/V2C composites, PVDF/V2C–TiO2 composites have an improved high dielectric constant, depressed low dielectric loss, and maintained high breakdown strength. High overall electric traits are ascribed to the synergy of conductive V2C and semiconductive TiO2. Outer and inner surfaces of V2C were ornament-combined by anatase-TiO2 particles having surface point defects as electron traps, contributing to low interface leakage conduction. Through density functional theory (DFT) calculations, nontypical V–F–Ti-bonding-induced dipole enhancement and Fermi-level (EF) overlapping-induced high electron localization mechanisms improve the dielectric response. Ternary composite with 10 wt % hybrid filler exhibits a dielectric constant of ∼99, a dielectric loss of ∼0.24 at 1 kHz, and a breakdown strength of ∼189 MV/m. This work might enable large-scale preparation of promising polymer/MXene composite dielectrics.
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高影响因子
Energy Technology
·
2020
·Vol. 8
·期 9
·2000444
·
IF 3.404
Xilai Xue,Xiangxin Zhang,Yongchuan Liu,Sujing Chen,Yuanqiang Chen,Junhong Lin,Yining Zhang
Solid-state poly(ethylene oxide) (PEO) electrolyte exhibits a low ionic conductivity at ambient conditions, and large interfacial resistance between PEO and electrodes obstructs its applications in lithium metal batteries. Heterogeneous solid electrolytes (HSEs) are an alluring solution for the exploitation of PEO. Herein, PEO/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/micron-sized Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 (LATP) heterogeneous solid electrolytes are originally prepared to decrease the crystallinity of PEO and interfacial resistance between HSEs and electrodes. Heterogeneous solid electrolyte composed of PEO/PVDF-HFP/5% micron-sized LATP (PPL-5) exhibits superior electrochemical properties in ionic conductivity (3.01 × 10 −5 S cm −1 ), lithium transference number (0.55) at 30 °C, and a broad potential window (5.31 V). Li/PPL-5/Li symmetric cell displays a relatively stable potential response during 800 h cycling, authenticating long-term compatibility between the as-prepared electrolyte and lithium metal. LiFePO 4 (LFP) is used as a cathode to test the chemical and electrochemical stability of PPL-5. The discharge capacity of LFP/PPL-5/Li coin cell maintains 97.9 mAh g −1 at 0.8 C after 500 cycles with capacity retention of 86.7%. Such excellent performance of PPL-5 can be ascribed to the reduction of crystallinity of PEO and the improvement of the interfacial contact between electrolyte and electrodes, when PVDF-HFP and micron-sized LATP are simultaneously incorporated with PEO electrolyte.
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