Membranes
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2021
·Vol. 12
·期 1
·57
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IF 4.106
Huan Liu,Quan Li,Benqiao He,Zhengguang Sun,Feng Yan,Zhenyu Cui,Jianxin Li
The efficient separation of Sr2+/Mg2+through nanofiltration (NF) technology is a great challenge because Sr2+and Mg2+ions are congeners with the same valence and chemical properties. In this work, an NF membrane under an electric field (EF) was successfully employed to separate Mg2+and Sr2+ions for the first time. The effects of current densities, Mg2+/Sr2+mass ratios, pH of the feed, and coexisting cations on separation performance were investigated. Dehydration of Sr2+or Mg2+ions under EF was proved by molecular dynamics simulation. The results showed that a high-efficient separation of Mg2+/Sr2+was achieved: Mg2+removal of above 99% and increase in Sr2+permeation with increasing EF. A separation factor reached 928 under optimal conditions, far higher than that without EF. The efficient separation of Mg2+/Sr2+ions was mainly due to rejection of most Mg2+ions by NF membrane and in situ precipitation of partly permeated Mg2+ions by OH−generated on the cathode under EF. Meanwhile, preferential dehydration of Sr2+ions under EF due to lower hydration energy of Sr2+compared with Mg2+resulted in an increase of permeation of Sr2+ions. This work provided a new idea for separation of congener ions with similar valence and chemical properties.Keywords:ENF process;congener ions;dehydration;efficient separation
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESALINATION
·
2024
·
IF 8.3
Tong Wu,Liu-Kun Wu,Hai-Tao Xu,Zhen-Liang Xu,Yong-Jian Tang
The TFC RO/NF membranes are the predominant membranes applied in desalination , and heat curing is an essential step in its industrial production, which increases the polyamide cross-linking degree and facilitate packing but leads permeability decrease. Nevertheless, the mechanism of heat curing on TFC membranes permeation resistance changes is still ambiguous. Figuring it out will aid in crafting a more effective optimization strategy in high flux membrane preparation. Herein, we prepared a range of TFC RO/NF membranes with various monomer concentrations on different substrates and quantified the permeation resistance changes by a resistance-in-series model. For nascent TFC RO/NF membranes, the PA layer provided almost all permeation resistance. After heat curing, the substrate exhibited a marked increase in permeation resistance. The change in the permeation resistance composition was further exacerbated by the decrease in monomer concentration. For TFC NF membranes with heat curing, the proportion of substrate permeation resistance increased significantly, rising from 31.62 % to 75.05 %. This study made a comprehensive analysis of the impact of the permeation resistance in TFC RO/NF membranes caused by heat curing, enriched the insight into the impact of heat curing on TFC membranes, and helped to prepare TFC membranes with better desalination performance.
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
ACS Applied Nano Materials
·
2022
·
IF 6.14
Jiqiao Liu,Quan Li,Yanhong Ji,Zhenyu Cui,Younas Mohammad,Jianxin Li,Benqiao He
Nanofiltration (NF) membranes commonly with a single polyamide (PA) barrier layer play a significant role in the fields of separation and purification. Herein, an NF membrane with double PA layers was successfully fabricated through interfacial polymerization (IP) of a diamine with trimesoyl chloride, and CaCO3 nanoparticles were used as scaffolds. The upper PA layer grounded on the nano-CaCO3 aggregates was incomplete with multidefects. Trimesoyl chloride solution could permeate through the multidefect PA layer to continue IP reaction with diamine underneath the multidefect PA layer to form a bottom defect-free PA layer. The double PA layers almost fitted together, and additional nanovoids were left after removing nano-CaCO3 particles by HCl. The NF membranes with double PA layers exhibited a high water permeance of 34.1 L·m–2·h–1·bar–1, 3.4-fold that of the control sample without sacrificing selectivity. This was attributed to the enhancement of the hydrophilicity and effective filtration area and decrease in PA layer thickness, as well as additional nanovoids to reduce transport resistance. The antifouling performance of the NF membrane was found to be superior to that of the control sample possibly because the upper thin PA layer as a protective layer reduced the contamination to the separation layer.
研究领域:
膜科学
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材料科学
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纳米技术
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环境工程
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产品关联
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Tian Gao,Ping Fu,Wan-Long Li,Wan-Ting Lin,Yuan-Hui Yu,Xiao-Jun Huang,Zhi-Kang Xu,Ling-Shu Wan
Nanofiltration (NF) membranes with superior permeability and selectivity are highly desirable for the applications. The development of non-polyamide loose NF membranes with high permeability and dye/salt selectivity has aroused great attention in recent years. In this work, 2-hydroxy-1,4-naphthoquinone, a natural compound commonly existed in plants, was chosen to prepare loose NF membranes via the co -deposition with polyethyleneimine (PEI). By optimizing the deposition conditions, we successfully fabricated amine-quinone network coatings on the surface of polyacrylonitrile (PAN) ultrafiltration membranes, and further cross-linked the coatings with glutaraldehyde to improve the compactness and stability. For this kind of loose NF membrane, the rejections to dyes with a molecular weight larger than 600 Da reach 98 %, and the water permeance keeps above 10 L·m −2 ·h −1 ·bar −1 . In contrast, the rejections to inorganic salts (NaCl, Na 2 SO 4 , MgCl 2 , and MgSO 4 ) are only about 10 %, and the selectivity of the dye molecule alcian blue against NaCl can reach 430. These results prove that this novel composite membrane can realize effective separation for dyes with different molecular weights and desalination for dye solutions. The present work will open up an avenue for designing loose NF membranes with novel separation layers.
研究领域:
膜科学
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材料科学
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环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2020
·
IF 7.183
Caini Liu,Wenyi Wang,Liuyong Zhu,Fangyan Cui,Chengcheng Xie,Xingyu Chen,Ning Li
A structurally controlled polyethersulfone (PES) membrane, as the substrate of the thin film composite nanofiltration (NF) membranes, was designed and fabricated with aligned carbon nanotubes (ACNTs) by a direct current electric field. The morphology and properties of the NF membranes were simultaneously affected by the PES substrate with especial macrovoids and ACNTs, increasing the permeability from 6.4 to 29.7 L/m 2 h bar. It was confirmed by FT-IR and XPS that the poly(piperazine amide) selective layer of the modified NF membrane has an increased content of –COOH for enhanced hydrophilicity. The zeta potential proves that the surface of the NF membrane modified by electric field has weaker negative charge than that of unmodified membrane in the range of pH = 5–9. Under the combined action of the Donnan effect and size exclusion, the rejection of MgCl 2 increased while maintaining the dianion rejection above 95%. Particularly, the NF membrane modified with ACNTs exhibited better chlorine resistance and antifouling ability, thus improving the stability and perdurability of membranes. Our work utilizes the characteristics of ACNTs to explore its potential in NF membranes.
研究领域:
材料科学
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化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Haojie Zeng,Feiyun Sun,Jianjun Zhang,Ying Wang,Songwen Yang,Dingyu Xing
Polyvinyl alcohol (PVA) has been employed and crosslinked as the selective layer of NF membranes with enhanced hydrophilicity. However, the influences of different crosslinking methods and agents on the reaction mechanism and membrane performance still need to be comprehensively studied. In this study, NF membranes were prepared by coating crosslinking (CC-membrane) and gradient crosslinking (GC-membrane) methods. Compared with CC-membrane, the GC-membrane possessed a 65% higher flux with Na 2 SO 4 rejection around 90%, under the optimal preparation conditions with PVA content of 0.10%, curing at 80 °C for 10 min. Crosslinking agents including 1,3,5-benzenetricarboxylic acid (TMA), 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and pyromellitic dianhydride (PMDA) with different spatial structure were used to optimize the GC-membrane. As confirmed by SEM, XPS, FTIR and contact angle tests, the 6FDA-GC membrane showed a thinner, smoother and more hydrophilic selective layer, and kept an excellent balance between the water flux (88.6 L/m 2 h) and Na 2 SO 4 rejection (88.7%). This is because the 6FDA with a large molecule and flexible spatial structure could form a more integrated crosslinking structure compared to PMDA. Meanwhile, the 6FDA-GC membrane showed rejections of over 80% towards the endocrine-disrupting compound 17α-Ethinylestradiol and exhibited stable antifouling ability and durability. Overall, this work studied systematically the influences of various crosslinking agents on the GC-membrane, and verified the potential of hydrophilic PVA membranes for nanofiltration.
研究领域:
材料科学
·
化学工程
·
环境科学
·
膜技术
✓ 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）