DESALINATION
·
2018
·
IF 6.603
Kang-Kang Yan,Lei Jiao,Saisai Lin,Xiaosheng Ji,Yin Lu,Lin Zhang
Electrospun nanofiber membranes (ENMs) have received increasing attentions in membrane distillation (MD) process due to their high porosity and interconnected open pores. However, the hydrophobicity of conventional ENMs depends on the used polymers, and the fabricated ENMs are still wetted during long-term operation. In this article, we present a facile surface coating technique for the fabrication of superhydrophobic ENMs through a spraying method. In this method, the low content of CNTs dispersion with a proper solvent plays an important role to prevent the agglomeration of CNTs. The scanning electron microscopy images showed that the carbon nanotubes (CNTs) were interlaced on polyvinylidene fluoride (PVDF) ENMs and formed a thin network layer. In order to have good bonding force with CNTs, the sprayed ENM was heat-pressed slightly below the PVDF melting point. Because of high hydrophobicity and low surface energy of CNTs, the fabricated membranes exhibited superhydrophobic property. The 20 g/m 2 CNTs coated membrane exhibited highest water flux (28.4 kg/m 2 h) with steady vacuum membrane distillation (VMD) performance >26 h. The morphology of CNTs coated membranes had no significant change after VMD test. The present study suggests that the CNTs network coated ENMs provide high potential applications towards VMD desalination .
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 Environmental Chemical Engineering
·
2025
·
IF 7.2
Peiqing Zhang,Sihang Li,Fan Xiao,Yongfang Xiao,Yi Zhang,Zhongguo Shan,Zhenyu Li,Haihua Wang
Membrane distillation (MD) represents a promising advance in wastewater purification, contributing to the mitigation of water scarcity. Hydrophobic poly(vinylidene fluoride) (PVDF) microporous membrane is susceptible to wetting by low surface tension substances, leading to fouling. To address this, PVDF membrane was superhydrophobically modified using modified ZIF-8 to obtain two composite membranes, AZ/PVDF and Z@C/PVDF. AZ/PVDF and Z@C/PVDF composite membranes were prepared by coating more dispersible APTES-ZIF-8 and ZIF-8@MWCNT, respectively, onto the surface of PVDF membrane. The hydrophobicity of the composite membranes was regulated by silane types, fluorination methods, and fluorination time, resulting in reduced surface roughness and increased surface energy. The contact angles of AZ/PVDF and Z@C/PVDF were 154.2 ± 3.4° and 156.8 ± 4.2°, respectively. Both AZ/PVDF and Z@C/PVDF membranes demonstrated outstanding mechanical, thermal, and chemical stability. AZ/PVDF and Z@C/PVDF membranes outperformed PVDF membrane, extending operation times by 2 h and 3 h, respectively, without obvious NaCl crystals. Furthermore, Z@C/PVDF membrane exhibited superior resistance to wetting by SDS than AZ/PVDF and PVDF membranes, treating pickle brine via the direct contact MD (DCMD) process with a recovery rate of 30.2 % within 10 h. Overall, this research offers a promising approach to fabricating superhydrophobic composite membranes for high-salt brine treatment via DCMD.
研究领域:
化学工程
·
材料科学
·
环境工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Xiaoju Yan,Chengyu Yang,Cong Ma,Hui Tao,Shirong Cheng,Lin Chen,Guodong Wang,Xinping Lin,Chengzhi Yao
Membrane fouling and wetting limit the applications of membrane distillation (MD) for wastewater treatment , especially when treating the wastewater with a high concentration of low surface tension substances such as oil and surfactants. In this paper, virgin polyvinylidene fluoride (PVDF) membrane was modified by polydimethylsiloxane (PDMS) to enhance anti-wetting ability. Then a thin polydopamine (PDA) layer was coated as a reaction platform for further modification. Polyethyleneimine (PEI) was cross-linked with PDA to form a uniform and stable layer, through hydrogen bonds and electrostatic interaction to immobilize hydrophilic MXene, which formed a Janus MXene-PVDF membrane. The MXene layer was the key for superoleophobicity and high liquid entry pressure (LEP) of membrane, capable of mitigating membrane fouling and wetting when dealing with low surface tension wastewater (LSTW). From the experiments results, pristine PVDF membrane showed severe fouling and wetting with flux decline and salt leakage during treatment of LSTW (surfactants containing water, oil-in-water emulsion and sodium dodecyl sulfate stabilized oil-in-water emulsion). However, under the same conditions, the Janus MXene-PVDF membrane exhibited remarkably stable flux (9.3 kg m −2 h −1 , 9.1 kg m −2 h −1 , 10.2 kg m −2 h −1 ) and salt rejection (almost 99.9%) after 15 h operation. Excellent fouling and wetting resistance of MXene-PVDF membrane was mainly attributed to its superhydrophilic and superoleophobic top surface (in-air water contact angle: 30.2°, under-water oil contact angle: 169.9°) and hydrophobic substrate (in-air water contact angle: 130.8°), together with high LEP value (91.1 Kpa). This study provides a viable route to fabricated a Janus membrane with outstanding fouling and wetting resistance for LSTW, oily wastewater and it has great potential for sewage treatment in the future.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2020
·
IF 5.774
Hongbin Li,Hengji Liu,Wenying Shi,Haixia Zhang,Rong Zhou,Xiaohong Qin
Mixed matrix membranes (MMMs) combine the advantages of different materials and hopefully break through the limitation of high mass transfer resistance and low permeability in membrane distillation (MD) process. In this study, hydrophobic zeolitic imidazolate framework-71 (ZIF-71)/polyvinylidene fluoride (PVDF) hollow fiber composite membrane was prepared by the dilute solution coating method. ZIF-71 was incorporated into the PVDF dilute solution and a macroporous hydrophobic ZIF-71/PVDF coating layer was formed on the outer surface of PVDF hollow fiber support membrane through the nonsolvent induced phase separation (NIPS) process. PVDF hollow fiber support membrane was fabricated by the dry-jet wet spinning process. Membrane surface morphologies were observed through Field emission scanning electron microscope (FESEM). The effects of zeolitic imidazolate frameworks (ZIFs) content in PVDF coating layer on membrane surface hydrophobicity and desalination performance were investigated through Dynamic water contact angle (WCA) measurements and the vacuum membrane distillation (VMD) experiment, respectively. The VMD experiment was carried out at feed temperature 50 °C and permeation side vacuum 31.3 kPa using 3.5 wt% NaCl aqueous solution as the feed solution. Compared with the uncoated PVDF hollow fiber membrane, both the surface hydrophobicity and the water permeability of the ZIFs-incorporated PVDF hollow fiber composite membranes are improved. The surface WCA and permeation water flux of ZIFs-PVDF composite membrane increase from 94.5 to 136.5° and 13.5 to 27.1 kg . m −2. h −1 meanwhile the NaCl rejection could maintain at 99.99%. No obvious pore wetting phenomenon was observed for ZIFs-PVDF hollow fiber composite membrane during the continuous VMD experiment for 60 h. The dilute solution coating is a promising method to prepare high-performance hollow fiber composite membrane for the desalination in MD process.
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
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2021
·
IF 9.028
Yuanmiaoliang Chen,Kang-Jia Lu,Wenxiao Gai,Tai-Shung Chung
Membranes with robust antiwetting and antifouling properties are highly desirable for membrane distillation (MD) of wastewater. Herein, we have proposed and demonstrated a highly effective method to mitigate wetting and fouling by designing nanofiltration (NF)-inspired Janus membranes for MD applications. The NF-inspired Janus membrane (referred to as PVDF-P-CQD) consists of a hydrophobic polyvinylidene fluoride (PVDF) membrane and a thin polydopamine/polyethylenimine (PDA/PEI) layer grafted by sodium-functionalized carbon quantum dots (Na+-CQDs) to improve its hydrophilicity. The vapor flux data have confirmed that the hydrophilic layer does not add extra resistance to water vapor transport. The PVDF-P-CQD membrane exhibits excellent resistance toward both surfactant-induced wetting and oil-induced fouling in direct contact MD (DCMD) experiments. The impressive performance arises from the fact that the nanoscale pore sizes of the PDA/PEI layer would reject surfactant molecules by size exclusion and lower the propensity of surfactant-induced wetting, while the high surface hydrophilicity resulted from Na+-CQDs would induce a robust hydration layer to prevent oil from attachment. Therefore, this study may provide useful insights and strategies to design novel membranes for next-generation MD desalination with minimal wetting and fouling propensity.
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
高影响因子
Membranes
·
2023
·Vol. 13
·期 2
·225
·
IF 4.2
Yubo Xu,Long-Fei Ren,Jun Li,Chengyi Wang,Yangbo Qiu,Jiahui Shao,Yiliang He
Membrane distillation (MD) is attractive for water reclamation due to the fact of its unique characteristics. However, membrane wetting becomes an obstacle to its further application. In this paper, a novel hydrophobic polyvinylidene fluoride/poly(vinyl pyrrolidone) (PVDF/PVP) membrane was fabricated by electrospinning and solvothermal treatment. The electrospun membranes prepared by electrospinning showed a multilevel interconnected nanofibrous structure. Then, a solvothermal treatment introduced the micro/nanostructure to the membrane with high roughness (Ra= 598 nm), thereby the water contact angle of the membrane increased to 158.3 ± 2.2°. Owing to the superior hydrophobicity, the membrane presented high resistance to wetting in both NaCl and SDS solutions. Compared to the pristine PVDF membrane, which showed wetting with a flux decline (120 min for 0.05 mM surfactant solution treatment), the prepared membrane showed outstanding stability over 600 min, even in 0.2 mM surfactant solutions. These results confirm a simple method for anti-wetting hydrophobic membrane preparation, which presented universal significance to direct contact membrane distillation (DCMD) for industrial application.Keywords:membrane distillation;membrane wetting;electrospinning;solvothermal treatment
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Haiyun Li,Zhengshi Yu,Yibo Lin,Wentian Zhang,Cunxian Lai,Lichao Xia,Fangang Meng,Shanshan Zhao
Membrane distillation (MD) is a promising technology for hypersaline wastewater treatment. However, commercial hydrophobic MD membrane usually suffers from severe wetting/fouling/scaling challenges that seriously hinder its wide applications. It is urgent to develop a robust MD membrane with simultaneous wetting/fouling/scaling resistance in a facile way. In this study, a Janus membrane with a dense hydrophilic nanofiltration top layer was simply fabricated by co-deposition of pyrogallic and polyethylenimine on hydrophobic polyvinylidene difluoride membrane followed by glutaraldehyde cross-linking. The Janus membrane can maintain stable performance during long-term treatment of saline wastewater containing surfactants, oil, and/or mineral ions, suggesting its excellent simultaneous wetting/fouling/scaling resistance. The mechanisms analyses reveal that the excellent wetting/fouling resistance is owed to the combined effects of strong surface hydration barrier, size exclusion, and strong capillary force. Moreover, the positively charged amino groups on the membrane surface further enhance the scaling resistance. Remarkably, the Janus membrane demonstrated exceptional performance during long-term (>100 h) treatment of ethylene waste lye, a hypersaline organic wastewater containing a broad spectrum of contaminants. The membrane possessed stable vapor flux and exhibited near-perfect salt rejection (99 %) and organic rejection (98 %). Our study provides a simple method for designing a robust Janus membrane for treating hypersaline organic wastewater and demonstrates the significant industrial application potential of MD technology.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2022
·Vol. 27
·期 3
·1057
·
IF 4.927
Kaiyun Fu,Yunzhao Guo,Wenbo Qi,Xianfu Chen,Minghui Qiu,Yiqun Fan
Ceramic membranes have the advantages of high mechanical strength and thermal stability and are promising candidates for membrane distillation. Ceramic membranes are generally designed to have a multilayer structure with different pore sizes to create a high liquid entry pressure and obtain a high permeability. However, these structural characteristics pose significant difficulties in predicting permeate flux in a ceramic membrane contactor for vacuum membrane distillation (VMD). Here, a modeling approach was developed to simulate the VMD process and verified by comparing the simulated results with the experimental data. Furthermore, correlations are proposed to simplify the calculations of permeate flux for VMD using asymmetric ceramic membranes by assuming those multilayers to be an effectively quasi-symmetric layer and by introducing a correction factor. The simulation results indicated that this simplified correlation was effective and enabled a quick estimation of the effect of membrane parameters on permeate flux.Keywords:ceramic membrane;vacuum membrane distillation;permeate flux;modeling
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESALINATION
·
2022
·
IF 11.211
Songchen Xie,Ngie Hing Wong,Jaka Sunarso,Qiang Guo,Chunguang Hou,Zhiguang Pang,Yuelian Peng
Mineral scaling is one of the major challenges for membrane distillation in concentrating high-salinity brine. This work first investigated the characteristic of CaSO 4 scaling, then explored different cleaning reagents to evaluate their efficiencies and mechanisms. By analyzing the SEM and EDX mapping images, the CaSO 4 scaling process could be divided into surface and pore scaling stages. Three cleaning solutions, i.e., commercial detergent (20 %), EDTA-4Na (0.05 M), and MgCl 2 (0.8 M), were chosen for their high CaSO 4 solubility (0.7 g CaSO 4 per 100 g H 2 O). At the surface scaling stage, three cleaning solutions exhibited excellent removal of CaSO 4 scaling with approximately similar 96 % cleaning efficiencies. However, at the pore scaling stage, only the commercial detergent showed high efficiency (89 %). Such high cleaning efficiency was mainly attributed to the detergent's high total dissolved solids (salinity), low pH, and high diffusion rate (5.46 μm cm −1 min −1 ) across the membrane. Moreover, periodic cleaning at the surface scaling stage with the commercial detergent followed by drying throughout a 43.5 h continuous concentration test on an actual RO brine could restore the PTFE membrane performance completely, giving 90 % of the total water recovery . This work provides new insights into the cleaning mechanism for gypsum scaling in a hydrophobic porous membrane.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Yin-Shuang Hu,Shuo-Chun Ke,Yu-Xi Huang
Membrane fouling and scaling are two critical challenges in membrane distillation (MD). The traditional superhydrophobic anti-scaling strategy is contradictory to the hydrophilic anti-fouling coating, creating a crucial challenge to combine these two properties into one material. In this study, glutamic acid (GA) was grafted on a polyvinylidene fluoride (PVDF) membrane surface to achieve fouling and scaling resistance simultaneously. The hydrophilic GA modification endowed the membrane with a larger underwater oil contact angle without affecting the surface morphology. The direct contact MD (DCMD) tests demonstrated that the GA-modified membrane had excellent oil fouling resistance due to the formation of a hydration layer by the GA molecules. In addition, the surface carboxyl groups offered plenty of coordination sites for metal ions, such as calcium ions. The surface coordination of calcium resulted in a lower free calcium concentration on the membrane surface, thereby postponing the scale nucleation and preventing the scales from intruding into the membrane matrix. The scaling tests also showed that the gypsum scales grown on the modified membrane were smaller than those on the pristine PVDF membrane. Besides, membrane cross-section analyses revealed that no scale intrusion was observed in the GA-modified membrane. Long-term stability tests and practical application with ethylene plant spent caustic further confirmed the promising application potential of the membrane. These results demonstrated that anti-fouling and anti-scaling properties can be integrated using the GA modification. This study provides a new surface modification strategy for designing and fabricating a robust anti-fouling and anti-scaling MD membrane.
研究领域:
材料科学
·
化学工程
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
npj Clean Water
·
2024
·Vol. 7
·期 1
·1-15
·
IF 10.4
Wu Zhuobin,Zheng Ke,Zhang Guichang,Huang Longwei,Zhou Shaoqi
Membrane distillation is an emerging wastewater treatment technology that harnesses low-grade heat as an energy source and exhibits potential for complete desalination. Nonetheless, two notable challenges hinder the practical application of this technology: membrane wetting and fouling. To counter these challenges, an innovative anti-fouling Janus membrane with asymmetric wettability was developed through electrospinning. The hydrophobic layer was formed using tetraethyl orthosilicate/polysulfone (PSF), and the superhydrophilic layer was created using polyvinylpyrrolidone (PVP)/PSF. A sensitive adhesion probe was used to assess the anti-fouling performance of the Janus membrane against oil. Molecular dynamics simulation suggested that PVP reduced the adsorption tendency of the membrane for humic acid (HA). Under experimental conditions involving saline water with HA and a saline oil–water emulsion, the non-Janus membrane suffered severe fouling, resulting in rapid water permeate flux decline. However, the Janus membrane demonstrated consistent permeate flux (26.84 LMH and 24.92 LMH) and an impressive salt rejection rate (> 99.99%). This study suggests that the Janus membrane, with its high permeate fluxes and remarkable resistance to fouling and wetting, could be an effective solution for wastewater treatment, with considerable potential for future application.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2020
·
IF 7.183
Shanshan Zhao,Zhu Tao,Muqiao Han,Yu-xi Huang,Bin Zhao,Liang Wang,Xuelin Tian,Fangang Meng
Conventional hydrophobic membranes are susceptible to membrane fouling and pore wetting, impeding the applications of membrane distillation (MD) processes for water recovery from complex wastewater. To address these challenges, we herein developed a novel Janus membrane by a hybrid plant-derived polyphenols coating and polyelectrolytes layer-by-layer assembly strategy. Through alternative deposition of catechol/chitosan and polyethylenimine (PEI) on top of a hydrophobic polyvinylidene fluoride (PVDF) substrate, a Janus membrane with a superhydrophilic and defect-free top layer was achieved. The synergistic effects of covalent bonding, non-covalent interactions, and electrostatic interactions between neighboring coatings endowed the membrane with robust chemical stability in the pH range of 2–12. In comparison with the pristine PVDF membrane, the Janus membrane exhibited remarkably stable water vapor flux and high quality of effluent during long-term treatments of non-ionic/cationic surfactants and Tween® 20-stabilized oil-in-water (O/W) emulsion in the bench-scale direct contact membrane distillation (DCMD) experiments. The excellent anti-fouling and anti-wetting properties of the Janus membrane were attributed to its hierarchical structured superhydrophilic surface, in which a strong hydration layer was formed and served as an energetic barrier to prevent adsorption of surfactants and oil droplets. Moreover, the electrostatic repulsion between the protonated amino groups on the membrane surface and cationic surfactant molecules also contributed to the robust long-term performance (nearly one-week operation) of the Janus membrane in the treatment of saline water containing cationic surfactant. Our findings reveal the significant role of surface functionality in fouling and wetting resistance of MD membranes and the as-developed Janus membrane shows great potential for water recovery from saline wastewater containing challenging contaminants via DCMD.
研究领域:
环境科学
·
材料科学
✓ 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）