Pub Date : 2024-11-28DOI: 10.1016/j.memsci.2024.123566
Caixia Wang , Bo Zhang , Shenzhen Cong , Chenglian Luo , Min Li , Zhecheng Guo , Zhi Wang , Xinlei Liu
High performance membranes for benzene/cyclohexane separation are crucial. Metal–organic frameworks (MOFs), given by their high structural designability, are expected to provide satisfying membrane performance for this separation. In this study, polymer chains were threaded into the pores of MOF UiO-66, to reconstruct the structures of the membrane channels. The permeance of benzene and selectivity of benzene/cyclohexane were boosted simultaneously, compared with the bare UiO-66 membranes. The performance enhancement was rationalized since the solubility of benzene was improved meanwhile the diffusivity of cyclohexane dropped by virtue of the new adsorption sites of benzene and narrower membrane channels created by threading polymers. The as-synthesized polyvinyl alcohol (PVA)-threaded UiO-66 membranes exhibited a benzene permeance around 110 GPU and a benzene/cyclohexane selectivity around 30.
{"title":"Threading MOF membranes with polymer chains for superior benzene/cyclohexane separation","authors":"Caixia Wang , Bo Zhang , Shenzhen Cong , Chenglian Luo , Min Li , Zhecheng Guo , Zhi Wang , Xinlei Liu","doi":"10.1016/j.memsci.2024.123566","DOIUrl":"10.1016/j.memsci.2024.123566","url":null,"abstract":"<div><div>High performance membranes for benzene/cyclohexane separation are crucial. Metal–organic frameworks (MOFs), given by their high structural designability, are expected to provide satisfying membrane performance for this separation. In this study, polymer chains were threaded into the pores of MOF UiO-66, to reconstruct the structures of the membrane channels. The permeance of benzene and selectivity of benzene/cyclohexane were boosted simultaneously, compared with the bare UiO-66 membranes. The performance enhancement was rationalized since the solubility of benzene was improved meanwhile the diffusivity of cyclohexane dropped by virtue of the new adsorption sites of benzene and narrower membrane channels created by threading polymers. The as-synthesized polyvinyl alcohol (PVA)-threaded UiO-66 membranes exhibited a benzene permeance around 110 GPU and a benzene/cyclohexane selectivity around 30.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123566"},"PeriodicalIF":8.4,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-28DOI: 10.1016/j.memsci.2024.123565
Wenxin Yan , Guangxiang Ma , Xinwei Kang , Zhe Yang , Fengxia Zhang , Daoji Wu , Min Song , Meng Li , Daliang Xu , Xuewu Zhu
Low-pressure, chlorine-resistant polyester (PE) nanofiltration (NF) membranes achieving superior organic matter/mineral selectivity are a promising candidate for producing healthy drinking water. However, PE-based NF membranes are mostly loosely structured, and less effective in removing natural organic matter. In this work, a maltitol monomer with a distorted non-planar structure was used to precisely regulate the properties of PE-based dense NF membranes (DNF) by thermal-modulated interfacial polymerization (TIP). The TIP contributed to the fast formation of a dense and highly crosslinked PE network on the support. The prepared DNF membranes were highly hydrophilic and electronegative. The non-volatile Isopar G was chosen as an organic solvent to minimize the nanobubble effect on PE membrane surface roughness, resulting in a relatively smooth membrane surface. The optimized [email protected] membrane exhibited satisfactory water permeance (15.7 L m−2 h−1 bar−1), DOC rejection (79.6 %), and outstanding chlorine resistance (48,000 ppm h). This study provides a new strategy for tailoring high-performance PE-based DNF membranes to treat natural surface water for healthy drinking water.
低压、耐氯聚酯（PE）纳滤（NF）膜具有优异的有机物/矿物选择性，是生产健康饮用水的有希望的候选者。然而，聚乙烯基滤膜大多结构松散，在去除天然有机物方面效果较差。本研究利用一种扭曲非平面结构的麦芽糖醇单体，通过热调节界面聚合（TIP）来精确调节聚乙烯基致密纳滤膜（DNF）的性能。TIP有助于在支架上快速形成致密且高度交联的PE网络。所制备的DNF膜具有高度亲水性和电负性。选择不挥发的等opar G作为有机溶剂，最大限度地减少纳米气泡对PE膜表面粗糙度的影响，从而获得相对光滑的膜表面。优化后的[email protected]膜具有良好的透水性（15.7 L m−2 h−1 bar−1），DOC截留率（79.6%）和出色的耐氯性（48,000 ppm h）。该研究为定制高性能pe基DNF膜处理天然地表水提供了新的策略。
{"title":"Thermal-modulated interfacial polymerization towards chlorine-resistant and dense polyester NF membranes for healthy drinking water","authors":"Wenxin Yan , Guangxiang Ma , Xinwei Kang , Zhe Yang , Fengxia Zhang , Daoji Wu , Min Song , Meng Li , Daliang Xu , Xuewu Zhu","doi":"10.1016/j.memsci.2024.123565","DOIUrl":"10.1016/j.memsci.2024.123565","url":null,"abstract":"<div><div>Low-pressure, chlorine-resistant polyester (PE) nanofiltration (NF) membranes achieving superior organic matter/mineral selectivity are a promising candidate for producing healthy drinking water. However, PE-based NF membranes are mostly loosely structured, and less effective in removing natural organic matter. In this work, a maltitol monomer with a distorted non-planar structure was used to precisely regulate the properties of PE-based dense NF membranes (DNF) by thermal-modulated interfacial polymerization (TIP). The <span>TIP</span> contributed to the fast formation of a dense and highly crosslinked PE network on the support. The prepared DNF membranes were highly hydrophilic and electronegative. The non-volatile Isopar G was chosen as an organic solvent to minimize the nanobubble effect on PE membrane surface roughness, resulting in a relatively smooth membrane surface. The optimized [email protected] membrane exhibited satisfactory water permeance (15.7 L m<sup>−2</sup> h<sup>−1</sup> bar<sup>−1</sup>), DOC rejection (79.6 %), and outstanding chlorine resistance (48,000 ppm h). This study provides a new strategy for tailoring high-performance PE-based DNF membranes to treat natural surface water for healthy drinking water.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123565"},"PeriodicalIF":8.4,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-28DOI: 10.1016/j.memsci.2024.123567
Xuan Wang , Yuxuan Yang , Zehua Li , Tiantian Li , Chunmei Niu , Ruolin Wang
Composite hydrogels offer significant potential in the development of nanofiltration membranes. Nonetheless, fabricating defect-free and ultra-thin polyamide membranes with wrinkled structure on three-dimensional composite hydrogel substrates through conventional interfacial polymerization remains a considerable challenge. Achieving both enhanced water permeability and ionic selectivity simultaneously is particularly challenging. In this study, a hydroxyl-enriched natural composite hydrogel, carboxyl methylated Astragalus gum/acid-soluble chitosan/multi-walled carboxylated carbon nanotubes (CTG/CS@CNT-COOH), was introduced as an intermediate layer to improve the process. This interlayer effectively enhanced PIP retention and reduced its diffusion rate into the organic phase by over 90 % through hydrogen bonding and physical barriers. The resulting polyamide layer, with a thickness of only 79.0 nm, exhibited a desirable wrinkled structure. SEM and AFM were employed to assess membrane morphology, while ATR-FTIR and XPS provided a detailed characterization of the membrane surface chemistry. The hydrophilicity and charge properties of various membranes were examined using water contact angle and zeta potential measurements. Notably, the modified thin-film composite membrane (TFC4) demonstrated exceptional pure water permeance, reaching 23.31 L m−2 h−1·bar−1, compared to 8.63 L m−2 h−1·bar−1 for TFC membrane lacking the composite hydrogel, alongside a Na2SO4 rejection rate of 98.38 %. Furthermore, the membrane exhibited strong fouling resistance and maintained structural integrity throughout extended filtration tests. This study presents a straightforward strategy for developing high-performance TFC membranes with enhanced efficiency.
复合水凝胶在纳滤膜的开发中具有重要的潜力。然而，通过传统的界面聚合在三维复合水凝胶基底上制造无缺陷的具有褶皱结构的超薄聚酰胺膜仍然是一个相当大的挑战。同时实现增强水渗透性和离子选择性是特别具有挑战性的。本研究以羧甲基化黄芪胶/酸溶性壳聚糖/多壁羧化碳纳米管（CTG/CS@CNT-COOH）为中间层，制备了一种富含羟基的天然复合水凝胶。该中间层有效地增强了PIP的保留，并通过氢键和物理屏障将其扩散到有机相的速率降低了90%以上。所得聚酰胺层厚度仅为79.0 nm，具有理想的皱褶结构。利用扫描电镜和原子力显微镜对膜的形貌进行了评估，而ATR-FTIR和XPS则对膜的表面化学进行了详细的表征。利用水接触角和zeta电位测定了不同膜的亲水性和电荷特性。值得注意的是，改性薄膜复合膜（TFC4）表现出优异的纯水渗透率，达到23.31 L m−2 h−1·bar−1，而缺乏复合水凝胶的TFC膜的纯水渗透率为8.63 L m−2 h−1·bar−1，Na2SO4的截留率为98.38%。此外，膜表现出很强的抗污性，并在长期过滤试验中保持结构完整性。本研究提出了一种开发高效TFC膜的直接策略。
{"title":"Natural composite hydrogel regulated interface polymerization to prepare high performance nanofiltration membranes with wrinkled structure","authors":"Xuan Wang , Yuxuan Yang , Zehua Li , Tiantian Li , Chunmei Niu , Ruolin Wang","doi":"10.1016/j.memsci.2024.123567","DOIUrl":"10.1016/j.memsci.2024.123567","url":null,"abstract":"<div><div>Composite hydrogels offer significant potential in the development of nanofiltration membranes. Nonetheless, fabricating defect-free and ultra-thin polyamide membranes with wrinkled structure on three-dimensional composite hydrogel substrates through conventional interfacial polymerization remains a considerable challenge. Achieving both enhanced water permeability and ionic selectivity simultaneously is particularly challenging. In this study, a hydroxyl-enriched natural composite hydrogel, carboxyl methylated Astragalus gum/acid-soluble chitosan/multi-walled carboxylated carbon nanotubes (CTG/CS@CNT-COOH), was introduced as an intermediate layer to improve the process. This interlayer effectively enhanced PIP retention and reduced its diffusion rate into the organic phase by over 90 % through hydrogen bonding and physical barriers. The resulting polyamide layer, with a thickness of only 79.0 nm, exhibited a desirable wrinkled structure. SEM and AFM were employed to assess membrane morphology, while ATR-FTIR and XPS provided a detailed characterization of the membrane surface chemistry. The hydrophilicity and charge properties of various membranes were examined using water contact angle and zeta potential measurements. Notably, the modified thin-film composite membrane (TFC4) demonstrated exceptional pure water permeance, reaching 23.31 L m<sup>−2</sup> h<sup>−1</sup>·bar<sup>−1</sup>, compared to 8.63 L m<sup>−2</sup> h<sup>−1</sup>·bar<sup>−1</sup> for TFC membrane lacking the composite hydrogel, alongside a Na<sub>2</sub>SO<sub>4</sub> rejection rate of 98.38 %. Furthermore, the membrane exhibited strong fouling resistance and maintained structural integrity throughout extended filtration tests. This study presents a straightforward strategy for developing high-performance TFC membranes with enhanced efficiency.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123567"},"PeriodicalIF":8.4,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-27DOI: 10.1016/j.memsci.2024.123564
Steven Schlosser, Wulin Qiu, Zhongyun Liu, Zachary S. Campbell, William J. Koros
Carbon molecular sieve (CMS) membranes have proven to be promising candidates for next-generation gas separations. Modification of polymeric precursors is a critical tool that permits fine-tuning of CMS structure and performance for a wide variety of gas mixtures. Here, we make a targeted alteration to a polyimide CMS precursor through substitution of free-volume-generating trifluoromethyl groups for aliphatic methyl groups on the polymer backbone. Gas separation performance shows a vast improvement, demonstrated by up to an eightfold increase in gas permeability as well as higher mixed gas separation factors in some cases. We investigate these properties, and their dependence on pyrolysis temperature, with detailed measurements of gas sorption and permeation in CMS dense film membranes with additional analysis through classical materials characterization methods. Our observations indicate that addition of free-volume-generating groups into polymeric precursors is a powerful tool for developing state-of-the-art CMS membranes, especially in cases when high permeability is an important design parameter.
{"title":"Leveraging molecular scale free volume generation to improve gas separation performance of carbon molecular sieve membranes","authors":"Steven Schlosser, Wulin Qiu, Zhongyun Liu, Zachary S. Campbell, William J. Koros","doi":"10.1016/j.memsci.2024.123564","DOIUrl":"10.1016/j.memsci.2024.123564","url":null,"abstract":"<div><div>Carbon molecular sieve (CMS) membranes have proven to be promising candidates for next-generation gas separations. Modification of polymeric precursors is a critical tool that permits fine-tuning of CMS structure and performance for a wide variety of gas mixtures. Here, we make a targeted alteration to a polyimide CMS precursor through substitution of free-volume-generating trifluoromethyl groups for aliphatic methyl groups on the polymer backbone. Gas separation performance shows a vast improvement, demonstrated by up to an eightfold increase in gas permeability as well as higher mixed gas separation factors in some cases. We investigate these properties, and their dependence on pyrolysis temperature, with detailed measurements of gas sorption and permeation in CMS dense film membranes with additional analysis through classical materials characterization methods. Our observations indicate that addition of free-volume-generating groups into polymeric precursors is a powerful tool for developing state-of-the-art CMS membranes, especially in cases when high permeability is an important design parameter.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123564"},"PeriodicalIF":8.4,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-27DOI: 10.1016/j.memsci.2024.123560
Hyeongrae Cho , Anja Krastel , Funda Arslan , Tobias Morawietz , Johannes Bender , Jochen Kerres , Vladimir Atanasov
Anion exchange membranes based on poly(pentafluorostyrene) (PPFSt) functionalized with tetramethylguanidinium are described in this study. By incorporating flexible thiohexyl groups onto PPFSt followed by functionalization with tetramethylguanidine and its quaternization with dimethylsulfate, free standing anion exchange membranes were fabricated. The resulting membranes were doped in phosphoric acid (PA) and applied for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The 60 % thiohexylated and 40 % tetramethylguanidinium-functionalized PPFSt membrane (M-PPFSt-TH-TMG) showed higher phosphoric acid doping level (ADL) than meta-PBI (m-PBI) membrane: 13.5 PA/guanidinium to 4.9 PA/imidazole respectively. Conductivity of the M-PPFSt-TH-TMG membrane displayed 322 mS cm−1 (ADL 13.5) and is therefore higher than the one of m-PBI membrane showing 203 mS cm−1 (ADL 4.5) at 160 °C. The fuel cell performance was measured at 160 °C with non-humidified gases and without back pressure on both anode and cathode sides and compared with commercial MEA (Celtec-P 1100W). A PA doped M-PPFSt-TH-TMG MEA showed higher performance than the commercial one exhibiting 793 and 656 mW cm−2 respectively measured under the same condition. The highest performance was obtained with the membrane M-PPFSt-TH-TMG: this membrane showed a peak power density of 1.31 W cm−2 in H2/O2 FC at 160 °C with 2 bars of backpressure on both anode and cathode sides. A stability test in FC showed no significant decay running at a constant current density of 217 mA cm−2 at 160 °C with non-humidified gases for 100 h. An accelerated stress test (AST) carried out via thermal cycling between 80 and 160 °C with humidified gases showed rapid decay over the first 20 cycles, followed by stabilization.
研究了四甲基胍功能化聚五氟苯乙烯（PPFSt）阴离子交换膜。通过在PPFSt上加入柔性的硫己基，然后用四甲基胍进行功能化，再用硫酸二甲基进行季铵化，制备了独立的阴离子交换膜。制备的膜在磷酸（PA）中掺杂，并应用于高温质子交换膜燃料电池（ht - pemfc）。60%硫己基化和40%四甲基胍功能化的PPFSt膜（M-PPFSt-TH-TMG）的磷酸掺杂水平（ADL）高于元pbi膜（m-PBI），分别为13.5 PA/胍和4.9 PA/咪唑。在160°C时，M-PPFSt-TH-TMG膜的电导率为322 mS cm−1 (ADL 13.5)，高于m-PBI膜的203 mS cm−1 （ADL 4.5）。在160°C、无加湿气体、阳极和阴极两侧无背压的条件下测量燃料电池的性能，并与商用MEA （Celtec-P 1100W）进行比较。在相同条件下，PA掺杂M-PPFSt-TH-TMG MEA的性能分别为793和656mw cm−2。M-PPFSt-TH-TMG膜的性能最好：在160°C的H2/O2 FC中，阳极和阴极两侧背压均为2 bar，该膜的峰值功率密度为1.31 W cm−2。在FC中进行的稳定性测试显示，在恒流密度为217 mA cm - 2、160°C、非湿化气体条件下，在100小时内没有明显的衰减。在80至160°C的热循环条件下进行的加速应力测试（AST）显示，在前20个循环中，使用湿化气体进行了快速衰减，随后趋于稳定。
{"title":"Novel guanidinium functionalized poly(pentafluorostyrene): Synthesis and application as ion-pair membrane in PA doped HT-PEMFC","authors":"Hyeongrae Cho , Anja Krastel , Funda Arslan , Tobias Morawietz , Johannes Bender , Jochen Kerres , Vladimir Atanasov","doi":"10.1016/j.memsci.2024.123560","DOIUrl":"10.1016/j.memsci.2024.123560","url":null,"abstract":"<div><div>Anion exchange membranes based on poly(pentafluorostyrene) (PPFSt) functionalized with tetramethylguanidinium are described in this study. By incorporating flexible thiohexyl groups onto PPFSt followed by functionalization with tetramethylguanidine and its quaternization with dimethylsulfate, free standing anion exchange membranes were fabricated. The resulting membranes were doped in phosphoric acid (PA) and applied for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The 60 % thiohexylated and 40 % tetramethylguanidinium-functionalized PPFSt membrane (M-PPFSt-TH-TMG) showed higher phosphoric acid doping level (ADL) than <em>meta</em>-PBI (<em>m</em>-PBI) membrane: 13.5 PA/guanidinium to 4.9 PA/imidazole respectively. Conductivity of the M-PPFSt-TH-TMG membrane displayed 322 mS cm<sup>−1</sup> (ADL 13.5) and is therefore higher than the one of <em>m</em>-PBI membrane showing 203 mS cm<sup>−1</sup> (ADL 4.5) at 160 °C. The fuel cell performance was measured at 160 °C with non-humidified gases and without back pressure on both anode and cathode sides and compared with commercial MEA (Celtec-P 1100W). A PA doped M-PPFSt-TH-TMG MEA showed higher performance than the commercial one exhibiting 793 and 656 mW cm<sup>−2</sup> respectively measured under the same condition. The highest performance was obtained with the membrane M-PPFSt-TH-TMG: this membrane showed a peak power density of 1.31 W cm<sup>−2</sup> in H<sub>2</sub>/O<sub>2</sub> FC at 160 °C with 2 bars of backpressure on both anode and cathode sides. A stability test in FC showed no significant decay running at a constant current density of 217 mA cm<sup>−2</sup> at 160 °C with non-humidified gases for 100 h. An accelerated stress test (AST) carried out via thermal cycling between 80 and 160 °C with humidified gases showed rapid decay over the first 20 cycles, followed by stabilization.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123560"},"PeriodicalIF":8.4,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.memsci.2024.123558
Xiaohu Zhai , Jianyu Hu , Zhong Chu , Jinghang Zou , Xuesong Li , Zhiwei Wang
Nanofiltration (NF) membranes are crucial for lithium (Li) recovery from salt-lake brine, but efficient Li/magnesium (Mg) separation remains challenging. This study employs the recently proposed S-JLi (separation factor vs Li flux) framework to evaluate NF membrane performance for Li/Mg separation, addressing limitations in traditional S-A (separation factor vs water permeance) frameworks. Using the Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE), we systematically investigate how operating conditions, feedwater properties, and membrane characteristics affect Li/Mg separation. Our results reveal that positively charged membranes outperform negatively charged ones, despite experiencing performance drops in high-salinity environments. We identify a trade-off between Li/Mg selectivity and Li flux that cannot be overcome by adjusting single membrane parameters. Multi-parameter synergistic regulation, particularly minimizing effective membrane thickness while optimizing charge density and pore size, emerges as a promising strategy to enhance separation performance. Our numerical simulations align well with experimental data, providing theoretical insights for designing high-performance Li/Mg separation membranes and emphasizing the importance of considering both selectivity and Li recovery in membrane development and evaluation.
{"title":"Rethinking nanofiltration membrane design for breaking the trade-off in Li/Mg separation: A comprehensive analysis based on the separation factor-lithium flux (S-JLi) framework","authors":"Xiaohu Zhai , Jianyu Hu , Zhong Chu , Jinghang Zou , Xuesong Li , Zhiwei Wang","doi":"10.1016/j.memsci.2024.123558","DOIUrl":"10.1016/j.memsci.2024.123558","url":null,"abstract":"<div><div>Nanofiltration (NF) membranes are crucial for lithium (Li) recovery from salt-lake brine, but efficient Li/magnesium (Mg) separation remains challenging. This study employs the recently proposed <em>S-J</em><sub>Li</sub> (separation factor vs Li flux) framework to evaluate NF membrane performance for Li/Mg separation, addressing limitations in traditional <em>S-A</em> (separation factor vs water permeance) frameworks. Using the Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE), we systematically investigate how operating conditions, feedwater properties, and membrane characteristics affect Li/Mg separation. Our results reveal that positively charged membranes outperform negatively charged ones, despite experiencing performance drops in high-salinity environments. We identify a trade-off between Li/Mg selectivity and Li flux that cannot be overcome by adjusting single membrane parameters. Multi-parameter synergistic regulation, particularly minimizing effective membrane thickness while optimizing charge density and pore size, emerges as a promising strategy to enhance separation performance. Our numerical simulations align well with experimental data, providing theoretical insights for designing high-performance Li/Mg separation membranes and emphasizing the importance of considering both selectivity and Li recovery in membrane development and evaluation.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123558"},"PeriodicalIF":8.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Covalent organic frameworks (COFs) have attracted great interest for the development of proton exchange membranes (PEMs) in the field of hydrogen fuel cells. However, the Grotthuss mechanism of proton transfer fails to discriminate the preferential pathways on the complicated hydrogen-bond network, thus limiting cell performance. Herein, a heterocharged COF lamellar membrane with cross-layer alternating paired charge distribution was fabricated by alternately assembling the positively charged TpEB and negatively charged TpPa-SO3H nanosheets. We demonstrated that the TpEB nanosheet drives the proton to directional transfer along the hydrogen-bond network on the sulfonic acid periphery of TpPa-SO3H by significantly reducing ineffective motions in branched hydrogen-bond network for both through-plane and in-plane directions. Meanwhile, it provides a low absorption energy for proton transfer from the sulfonic acid shell. This assembly effect occurs within the three nanosheet layers during each alternate film formation (A3B3) and contributes to the long-term stability of the proton conductivity for TpEB@TpPa-SO3H. Notably, it achieves a maximum power density of 223 mW cm−2 at 60 °C and 100 % RH, which is superior to those of 83 mW cm−2 and 22 mW cm−2 for the homocharged TpPa-SO3H and TpEB membranes, respectively. This work provides new insights into the design of high-conductivity PEMs from engineered COF membranes.
{"title":"Cross-layer alternating paired charge distribution to boost proton conductivity of COF lamellar membrane","authors":"Yuqing Xue, Xingke Yuan, Chongchong Chen, Wenpeng Li, Wenjia Wu, Zhirong Yang, Jingtao Wang","doi":"10.1016/j.memsci.2024.123556","DOIUrl":"10.1016/j.memsci.2024.123556","url":null,"abstract":"<div><div>Covalent organic frameworks (COFs) have attracted great interest for the development of proton exchange membranes (PEMs) in the field of hydrogen fuel cells. However, the Grotthuss mechanism of proton transfer fails to discriminate the preferential pathways on the complicated hydrogen-bond network, thus limiting cell performance. Herein, a heterocharged COF lamellar membrane with cross-layer alternating paired charge distribution was fabricated by alternately assembling the positively charged TpEB and negatively charged TpPa-SO<sub>3</sub>H nanosheets. We demonstrated that the TpEB nanosheet drives the proton to directional transfer along the hydrogen-bond network on the sulfonic acid periphery of TpPa-SO<sub>3</sub>H by significantly reducing ineffective motions in branched hydrogen-bond network for both through-plane and in-plane directions. Meanwhile, it provides a low absorption energy for proton transfer from the sulfonic acid shell. This assembly effect occurs within the three nanosheet layers during each alternate film formation (A<sub>3</sub>B<sub>3</sub>) and contributes to the long-term stability of the proton conductivity for TpEB@TpPa-SO<sub>3</sub>H. Notably, it achieves a maximum power density of 223 mW cm<sup>−2</sup> at 60 °C and 100 % RH, which is superior to those of 83 mW cm<sup>−2</sup> and 22 mW cm<sup>−2</sup> for the homocharged TpPa-SO<sub>3</sub>H and TpEB membranes, respectively. This work provides new insights into the design of high-conductivity PEMs from engineered COF membranes.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123556"},"PeriodicalIF":8.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.memsci.2024.123557
Yanting Tang , Qingnan Wang , Xiaohe Tian , Chenlu Liu , Keming Zhang , Xiaoting Feng , Rui Zhang , Yueyangchao Yu , Shaofei Wang
Covalent organic frameworks (COFs), characterized by their well-organized porous structure, exhibit promising prospects for carbon capture. Nevertheless, their weak film-forming property and relatively large pore sizes constrain their utilization as gas separation membranes. This study introduced a facile approach to fabricating COF membranes tailored for CO2 separations. By introducing an extra monomer, trimesoyl chloride (TMC), together with COF monomers, a thin and defect-free layer of COF-polyamide was synthesized by interfacial polymerization process. The amide structure embedded into the COFs layers was expected to mend the defects, strengthen the binding forces, and improve the stability of the COFs layers. To further enhance the performance, imidazolium ionic liquid (IL) was adopted to modify the COF-polyamide layer. The introduction of TMC rendered the COF-polyamide layer more negatively charged, facilitating stronger binding to the positively charged cations in the IL. This modification with IL effectively reduced the pore size of the COFs and increased the affinity for CO2. The resultant COF composite membranes exhibited a high CO2 permeance of 125.9 GPU and CO2/N2 selectivity up to 35.0, accompanied by robust long-term stability. Our method paves a new way for the fabrication and application of interfacial polymerized COF membranes for gas separation applications.
共价有机框架（COFs）具有组织良好的多孔结构，在碳捕集方面前景广阔。然而，它们的弱成膜特性和相对较大的孔径限制了它们作为气体分离膜的应用。本研究介绍了一种制造 COF 膜的简便方法。通过在 COF 单体中引入额外的单体--三甲基甲酰氯（TMC），利用界面聚合工艺合成了一层薄而无缺陷的 COF 聚酰胺。嵌入 COFs 层中的酰胺结构有望修补缺陷、增强结合力并提高 COFs 层的稳定性。为了进一步提高性能，采用了咪唑离子液体（IL）来修饰 COF 聚酰胺层。TMC 的引入使 COF 聚酰胺层带更多负电荷，有利于与 IL 中带正电荷的阳离子更紧密地结合。这种对 IL 的改性有效地缩小了 COF 的孔径，增加了对 CO2 的亲和力。最终得到的 COF 复合膜具有 125.9 GPU 的高 CO2 渗透率和高达 35.0 的 CO2/N2 选择性，并具有长期稳定性。我们的方法为气体分离应用中界面聚合 COF 膜的制造和应用铺平了新的道路。
{"title":"Interfacial polymerization of COF-polyamide composite membranes modified with ionic liquids for CO2 separations","authors":"Yanting Tang , Qingnan Wang , Xiaohe Tian , Chenlu Liu , Keming Zhang , Xiaoting Feng , Rui Zhang , Yueyangchao Yu , Shaofei Wang","doi":"10.1016/j.memsci.2024.123557","DOIUrl":"10.1016/j.memsci.2024.123557","url":null,"abstract":"<div><div>Covalent organic frameworks (COFs), characterized by their well-organized porous structure, exhibit promising prospects for carbon capture. Nevertheless, their weak film-forming property and relatively large pore sizes constrain their utilization as gas separation membranes. This study introduced a facile approach to fabricating COF membranes tailored for CO<sub>2</sub> separations. By introducing an extra monomer, trimesoyl chloride (TMC), together with COF monomers, a thin and defect-free layer of COF-polyamide was synthesized by interfacial polymerization process. The amide structure embedded into the COFs layers was expected to mend the defects, strengthen the binding forces, and improve the stability of the COFs layers. To further enhance the performance, imidazolium ionic liquid (IL) was adopted to modify the COF-polyamide layer. The introduction of TMC rendered the COF-polyamide layer more negatively charged, facilitating stronger binding to the positively charged cations in the IL. This modification with IL effectively reduced the pore size of the COFs and increased the affinity for CO<sub>2</sub>. The resultant COF composite membranes exhibited a high CO<sub>2</sub> permeance of 125.9 GPU and CO<sub>2</sub>/N<sub>2</sub> selectivity up to 35.0, accompanied by robust long-term stability. Our method paves a new way for the fabrication and application of interfacial polymerized COF membranes for gas separation applications.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123557"},"PeriodicalIF":8.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-25DOI: 10.1016/j.memsci.2024.123552
Long Han , Shoutao Gong , Haiyang Zhang , Min Yang , Omer Javed , Xiaoming Yan , Gaohong He , Fengxiang Zhang
Highly conductive and robust anion exchange membrane (AEM) is the key for development of alkali fuel cell and electrodialysis. We herein report novel, branched polyarylpiperidinium AEMs containing 1,3-dicarbazole-9-ylbenzene (DCB) unit. As a larger, more rigid branching unit relative to the conventional one, DCB can create higher fraction of free volume in the AEM, induce more significant microphase separation and better restrict water swelling of the membrane. The prepared qTPDCB-5.5 AEM exhibited an excellent hydroxide conductivity (175.3 mS cm−1) and a low swelling ratio (21 %) at 90 °C; when soaked in aqueous sodium hydroxide solution (2 mol/L, 80 °C) for 1000 h, qTPDCB-5.5 showed a high conductivity retention (96.5 %). Its hydrogen/oxygen fuel cell reached an impressive peak power density (1.83 W cm−2), and the qTPDCB-5.5 AEM did not experience appreciable structural decomposition after the cell worked at 0.2 A cm−2 for 230 h (including >100 h intermittent discharge). Owing to its high conductivity and swelling resistance, the qTPDCB-5.5 membrane also showed good performance in electrodialysis, and gave rise to low energy consumption (2.72 kWh kg−1) when used for desalinating 0.1 M NaCl solution. This work highlights the importance and provides the methodology of incorporating large, rigid branching unit in the structure of high performance AEM for fuel cell and electrodialysis applications.
高导电性和坚固耐用的阴离子交换膜（AEM）是开发碱燃料电池和电渗析的关键。我们在此报告了含有 1,3-二咔唑-9-基苯 (DCB) 单元的新型支化聚芳基哌啶 AEM。与传统的支化单元相比，DCB 是一种更大、更硬的支化单元，它能在 AEM 中产生更高的自由体积分数，诱导更显著的微相分离，并能更好地限制膜的水膨胀。制备的 qTPDCB-5.5 AEM 在 90 ℃ 时表现出优异的氢氧化物电导率（175.3 mS cm-1）和较低的膨胀率（21%）；在氢氧化钠水溶液（2 mol/L，80 ℃）中浸泡 1000 小时后，qTPDCB-5.5 表现出较高的电导率保持率（96.5%）。它的氢/氧燃料电池达到了惊人的峰值功率密度（1.83 W cm-2），而且 qTPDCB-5.5 AEM 在 0.2 A cm-2 的条件下工作 230 小时（包括 100 小时间歇放电）后没有出现明显的结构分解。由于qTPDCB-5.5膜具有高导电性和抗溶胀性，因此在电渗析中也表现出了良好的性能，在用于淡化0.1 M NaCl溶液时，能耗较低（2.72 kWh kg-1）。这项工作强调了在燃料电池和电渗析应用的高性能 AEM 结构中加入大型刚性分支单元的重要性，并提供了相关方法。
{"title":"High performance anion exchange membrane containing large, rigid branching structural unit for fuel cell and electrodialysis applications","authors":"Long Han , Shoutao Gong , Haiyang Zhang , Min Yang , Omer Javed , Xiaoming Yan , Gaohong He , Fengxiang Zhang","doi":"10.1016/j.memsci.2024.123552","DOIUrl":"10.1016/j.memsci.2024.123552","url":null,"abstract":"<div><div>Highly conductive and robust anion exchange membrane (AEM) is the key for development of alkali fuel cell and electrodialysis. We herein report novel, branched polyarylpiperidinium AEMs containing 1,3-dicarbazole-9-ylbenzene (DCB) unit. As a larger, more rigid branching unit relative to the conventional one, DCB can create higher fraction of free volume in the AEM, induce more significant microphase separation and better restrict water swelling of the membrane. The prepared qTPDCB-5.5 AEM exhibited an excellent hydroxide conductivity (175.3 mS cm<sup>−1</sup>) and a low swelling ratio (21 %) at 90 °C; when soaked in aqueous sodium hydroxide solution (2 mol/L, 80 °C) for 1000 h, qTPDCB-5.5 showed a high conductivity retention (96.5 %). Its hydrogen/oxygen fuel cell reached an impressive peak power density (1.83 W cm<sup>−2</sup>), and the qTPDCB-5.5 AEM did not experience appreciable structural decomposition after the cell worked at 0.2 A cm<sup>−2</sup> for 230 h (including >100 h intermittent discharge). Owing to its high conductivity and swelling resistance, the qTPDCB-5.5 membrane also showed good performance in electrodialysis, and gave rise to low energy consumption (2.72 kWh kg<sup>−1</sup>) when used for desalinating 0.1 M NaCl solution. This work highlights the importance and provides the methodology of incorporating large, rigid branching unit in the structure of high performance AEM for fuel cell and electrodialysis applications.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123552"},"PeriodicalIF":8.4,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The membranes for membrane distillation (MD) posed challenges for long-term stable operation due to poor mechanical strength, low flux and susceptibility to wetting. In this study, inspired by conventional mortise and tenon (MT) structure, we constructed a novel robust and porous bilayer composite membrane consisting of superhydrophobic microsphere layer and nanofibrous substrate along with interfacial interlocked networks via a facile integrated casting-recrystallization (ICR) method for highly efficient direct contact membrane distillation (DCMD). During one-step ICR process, amorphous polypropylene (aPP) and isotactic polypropylene (iPP) (a-iPP) with certain mass ratio were completely dissolved in xylene and then cast on the surface of highly porous poly(vinylidene fluoride) (PVDF) nanofibrous substrate at high temperature, in which a crystallization process of the mixed solution occurred in a single step to form PP microsphere layer with a flower-like structure for guarantee of the superhydrophobicity and permeability of the composite membrane. Meanwhile, PP solution infiltrated into the PVDF nanofibrous substrate and then solidified along the fibers and fiber junctions at the initial pouring to create intermediate interlocking connections based on MT construction between the nanofibrous substrate and the microsphere layer, which resulted in the composite membrane with extremely high structural integrity and mechanical properties. The optimal a-iPP/PVDF composite membranes exhibited outstanding mechanical properties (36.6 MPa in tensile strength and 118.0% in strain), significantly superior to PVDF electrospun nanofibrous membrane and commercial PVDF membrane. This unique a-iPP composite membrane with unrelenting superhydrophobicity and high permeability demonstrated a complete barrier to salts with a considerable permeation flux of 54 kg m−2 h−1 in a 70-h DCMD test (ΔT = 40 °C).
膜蒸馏（MD）用膜由于机械强度差、通量低、易润湿等问题，对长期稳定运行提出了挑战。在这项研究中，我们受到传统的mts （MT）结构的启发，通过简单的集成铸造-再结晶（ICR）方法构建了一种新型的坚固的多孔双层复合膜，该复合膜由超疏水微球层和纳米纤维衬底以及界面互锁网络组成，用于高效的直接接触膜蒸馏（DCMD）。在一步ICR工艺中，将一定质量比的非晶聚丙烯（aPP）和等规聚丙烯（iPP） （a-iPP）完全溶解在二甲苯中，然后在高温下浇铸在高孔聚偏氟乙烯（PVDF）纳米纤维基体表面。其中，混合溶液的结晶过程一步完成，形成了具有花状结构的PP微球层，保证了复合膜的超疏水性和渗透性。同时，PP溶液渗透到PVDF纳米纤维基板中，并在浇注初期沿纤维和纤维连接处固化，在纳米纤维基板与微球层之间形成基于MT结构的中间互锁连接，使复合膜具有极高的结构完整性和力学性能。优化后的a-iPP/PVDF复合膜具有优异的力学性能（抗拉强度为36.6 MPa，应变为118.0%），明显优于PVDF静电纺纳米纤维膜和商用PVDF膜。这种独特的a- ipp复合膜具有不间断的超疏水性和高渗透性，在70小时的DCMD测试（ΔT = 40°C）中，通过54 kg m−2 h−1的相当大的渗透通量，证明了对盐的完全屏障。
{"title":"Highly durable superhydrophobic bilayer nanofibrous composite membrane with intermediate interlocked network inspired by mortise and tenon connections for membrane distillation","authors":"Luheng Jing , Tonghui Zhang , Siping Ding , Zheyi Meng , Xuefen Wang","doi":"10.1016/j.memsci.2024.123553","DOIUrl":"10.1016/j.memsci.2024.123553","url":null,"abstract":"<div><div>The membranes for membrane distillation (MD) posed challenges for long-term stable operation due to poor mechanical strength, low flux and susceptibility to wetting. In this study, inspired by conventional mortise and tenon (MT) structure, we constructed a novel robust and porous bilayer composite membrane consisting of superhydrophobic microsphere layer and nanofibrous substrate along with interfacial interlocked networks via a facile integrated casting-recrystallization (ICR) method for highly efficient direct contact membrane distillation (DCMD). During one-step ICR process, amorphous polypropylene (aPP) and isotactic polypropylene (iPP) (a-iPP) with certain mass ratio were completely dissolved in xylene and then cast on the surface of highly porous poly(vinylidene fluoride) (PVDF) nanofibrous substrate at high temperature, in which a crystallization process of the mixed solution occurred in a single step to form PP microsphere layer with a flower-like structure for guarantee of the superhydrophobicity and permeability of the composite membrane. Meanwhile, PP solution infiltrated into the PVDF nanofibrous substrate and then solidified along the fibers and fiber junctions at the initial pouring to create intermediate interlocking connections based on MT construction between the nanofibrous substrate and the microsphere layer, which resulted in the composite membrane with extremely high structural integrity and mechanical properties. The optimal a-iPP/PVDF composite membranes exhibited outstanding mechanical properties (36.6 MPa in tensile strength and 118.0% in strain), significantly superior to PVDF electrospun nanofibrous membrane and commercial PVDF membrane. This unique a-iPP composite membrane with unrelenting superhydrophobicity and high permeability demonstrated a complete barrier to salts with a considerable permeation flux of 54 kg m<sup>−2</sup> h<sup>−1</sup> in a 70-h DCMD test (ΔT = 40 °C).</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"717 ","pages":"Article 123553"},"PeriodicalIF":8.4,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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