JOURNAL OF MEMBRANE SCIENCE
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2022
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IF 10.53
Dejun Feng,Xianhui Li,Zhangxin Wang
Membrane wetting, fouling, and scaling are three prominent challenges that limit membrane distillation (MD) applications. To overcome these challenges, novel MD membranes including omniphobic membranes and Janus membranes with a dense hydrophilic surface layer have been developed. In this study, we fabricated an omniphobic membrane and a Janus membrane composed of a dense polyvinyl alcohol (PVA) surface layer and a polyvinylidene fluoride (PVDF) substrate. The two membranes have been compared in MD experiments with different feeds. Furthermore, the working mechanisms of the two membranes have been elucidated. As a result, neither the omniphobic MD membrane nor the Janus MD membrane can resolve all three challenges at the same time. Specifically, both the omniphobic MD membrane and Janus MD membrane can resist wetting but via different working mechanisms. From breakthrough pressure (BP) determinations with an ethanol-water mixture (i.e., a low-surface-tension liquid), the omniphobic MD membrane resists wetting as its LEP (82.0 ± 9.2 kPa) is larger than the transmembrane pressure in the MD operation, while the Janus MD membrane resists wetting because the huge capillary pressure (550 ± 50 kPa) in the dense hydrophilic surface layer retains the wetting solution. The omniphobic MD membrane is prone to oil fouling because of the strong underwater hydrophobic attraction between the membrane surface and the mineral oil droplets, while the Janus MD membrane can substantially mitigate fouling due to the lack of attraction between the mineral oil droplets and the hydrophilic membrane surface. The omniphobic MD membrane exhibits outstanding scaling resistance because minerals can hardly precipitate and/or crystalize on the membrane surface, while the Janus MD membrane was susceptible to scaling due to the precipitation and/or crystallization of minerals inside the hydrophilic surface layer. Therefore, the selection of MD membranes should depend on the feed constituents. Overall, our study provides important guidelines for the future development of robust MD membranes.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Wei Zhang,Zhi Wang,Baoan Li
Omniphobic membranes have acquired some recognitions for alleviating the membrane wetting in the robust membrane distillation because of the super-repulsion towards different surface tension liquids. In this study, the Ti-CNFs/PVDF composite membrane with omniphobicity and high permeate flux was fabricated via electrospraying multilevel heat-conducting nanofibers on the PVDF membrane and fluorosilane treatment simultaneously with one-step strategy. In detail, carbon nanofibers decorated by TiO 2 with hydrothermal treatment were immobilized on the surface by the adhesive attraction of PDMS to establish the re-entrant structure. Meanwhile, 1H,1H,2H,2H-perfluorodecyltriethoxysilane was presented in the spraying liquid to gain the low surface energy for the surface. Additionally, the composite nanofibers played a role in mitigating the temperature polarization. A series of characterizations on membrane morphologies, wetting behaviors, structural peculiarities and stable properties were investigated systematically. The results showed that the re-entrant morphology consisted of the intersecting nanofibers was constructed skillfully, looking like the nest's hierarchical structure. The composite membrane displayed outstanding contact angles of 172.0 ± 1.8°, 170.5 ± 3.5°, 160.1 ± 2.6°, 165.0 ± 3.0°, 162.5 ± 4.5°, 151.0 ± 1.5°, 153.5 ± 3.5° and 118.0 ± 3.0° towards DI water , 3.5 wt% NaCl, 0.4 mM SDS , 0.4 mM CTAB, 0.4 mM Tween-20, ethanol, soybean milk and dodecane, respectively. The modified membrane presented a 167% LEP measurement of the pristine membrane and satisfactory chemical and thermal stabilities along with silver mirror phenomena. Furthermore, the omniphobic membrane exhibited anti-fouling and anti-wetting performances with high and stable permeate fluxes (36.3 kg/m 2 ·h) as well as a nearly 100% salt rejection rate in the consecutive DCMD tests, where HA and diverse surfactants were added to the brine feed. This suggests the omniphobic membrane as a promising alternative for wastewater treatment in membrane distillation.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
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IF 10.53
Songchen Xie,Zhiguang Pang,Chunguang Hou,Ngie Hing Wong,Jaka Sunarso,Yuelian Peng
Membrane scaling represents one of the significant challenges for membrane distillation (MD), especially when treating hypersaline brines. This work presents a one-step dip-coating method to develop an omniphobic membrane. The commercial polyvinylidene fluoride (PVDF) hydrophobic porous membranes were immersed into the epoxy acrylic (EA) resin and fluorosilane (1H,1H,2H,2H-Perfluorodecyltrimethoxysilane, PFTS) mixture followed by a heating cross-linking process. EA/PFTS ratio of 1:1 (v/v) gave the best performance regarding surface morphology , surface chemical composition, surface energy, and mechanical property. The resultant PVDF-(EA/PFTS)-1:1 membrane demonstrated excellent wetting resistance and omniphobicity during the penetration of deionized water , 30% and 60% ethanol in water, and kerosene, giving 141°, 124°, 106°, and 116° contact angles, respectively. It also exhibited excellent scaling resistance in concentrating 14.7 mM gypsum solution and actual reverse osmosis (RO) brine. The permeate flux and conductivity were maintained at about 14 kg m −2 h −1 and below 3 μS cm −1 , respectively. More than 99% salt rejection (actual RO brine) was achieved during a long-term continuous MD operation for 80 h. The PVDF-(EA/PFTS)-1:1 membrane exhibited excellent anti-scaling and anti-wetting properties. A series of capillary experiments confirmed that the membrane's surface pores achieved the gas-wetting state. The increase in the membrane surface hydrophobicity , the reduction in the surface pore size, and the toughening of the surface pores contributed to the formation of a stable gas-liquid interface on the modified membrane surface that can enhance the anti-scaling and anti-wetting performance.
研究领域:
环境科学
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材料科学
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化学工程
✓ 已验证
DOI
高影响因子
Membranes
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2025
·Vol. 15
·期 9
·271
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IF 3.6
Jie Xu,Jinxin Liu,Mei-Ling Liu,Guangze Nie,Dong Zou
Membrane distillation demonstrates ideal separation performance towards saline water; however, it fails to accomplish the classification and recovery of multiple components from complex saline solutions (i.e., heavy metal ion-laden saline water in process industries). Herein, an adsorption–membrane distillation (MD) coupling process was proposed, as an example of a Pb(II)/NaCl mixed solution, in which the prepared adsorption membrane was firstly employed to adsorb heavy metal ions in the mixed solution and then the brine was concentrated by the MD process to realize water source recovery and utilization. Firstly, an FeOOH@PVDF adsorptive membrane was fabricated to adsorb Pb(II) ions. It was demonstrated that chemical adsorption was identified as the dominant mechanism, and the composite membrane showed excellent selective adsorption for Pb(II). Following this, the omniphobic membrane was then employed to concentrate the Pb(II)-removed saline solution, maintaining a water flux of 16.12 kg·m−2·h−1at a concentration factor of 7.7, demonstrating excellent MD concentration performance. Through this coupled process, the saline wastewater containing heavy metal ions was successfully separated into purified water and concentrated brine without heavy metal ions, providing a novel approach for the treatment and recycling of complex saline wastewater.
研究领域:
环境工程
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化学工程
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材料科学
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水处理技术
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分离科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESALINATION
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2025
·
IF 9.8
Ronghua Ma,Xiaolong Lu,Jie Gu,Kai Ren,Yuling Ren,Yuefei Song,Zhong Ma
With a high rejection rate for salts and non-volatile organic compounds, membrane distillation (MD) is widely used in in the treatment of hypersaline wastewater. However, the performance degradation of membranes caused by pore-wetting, mineral scaling or structural instability greatly limits their development potential. Improving the durability of service performance in MD process has become the focus of the scientific community. Herein, we anchored the fluor‑silicon island structure with low-surface-energy onto the poly(vinylidene fluoride- co -chlorotrifluoroethylene) (PVDF-CTFE) membrane surface by covalent bonding based on C Cl, so as to construct an omniphobic membrane with excellent anti-fouling and anti-wetting performance. Through the characterization of the surface morphology, element composition and basic physicochemical properties of the membrane, it was demonstrated that the discontinuous island-structure was successfully anchored on the membrane surface through chemical bonds, endowing the modified membrane with a higher gas-permeability coefficient and liquid entry pressure (LEP w > 4.0 bar), and exhibiting outstanding gas-permeability and water-impermeability. Meanwhile, it has a high contact angle for water (154.0°), brine (152.2°), Sodium Dodecyl Sulfonate (SDS) salt solution (150.5°), and soybean oil emulsion (123.1°), showing excellent lyophobic properties. Experimentally, it was demonstrated that the modified membrane had higher vapor-flux (≥ 23.0 kg m −2 h −1 ), lower irreversible flux decay rate (< 8.8 %), and could be continuously and stably operated for 60 h with excellent performance compared with the original membrane, homogeneous coating or electrostatic adsorption modified membranes. Treating hypersaline wastewater with complex components, it still exhibits excellent stability, anti-wetting, and anti-fouling performance after long-term operation.
研究领域:
环境工程
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膜科学
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）