A novel strategy was developed to regulate polyamide (PA) membrane morphology and performance by introducing a reactive copolymer, poly(styrene-alt-maleic anhydride) (PSMA), into the polyethersulfone (PES) substrate. The reactive anhydride groups of PSMA first react with piperazine (PIP) monomers, subsequently affecting diffusion and reaction dynamics of the remaining monomers during interfacial polymerization (IP) for PA layer formation. As a result, wrinkled PA morphologies were formed, enhancing the surface roughness and effective filtration area. The wrinkled PA membranes exhibited significantly improved water permeance (up to 19.7 L m-2 h-1 bar-1) while maintaining comparable rejection rates of 98.7 %, 98.2 %, 85.7 %, 6.1 %, 7.1 % for Na2SO4, MgSO4, MgCl2, LiCl, and NaCl, respectively, due to the similar free volume to unmodified membranes. This work offers a promising approach to tailor membrane structure and optimize nanofiltration performance via substrate reactivity engineering.
{"title":"Reactive substrate-driven interfacial polymerization for wrinkled polyamide membranes with enhanced permeance","authors":"Ping Xu , Shaofan Duan , Pengfei Zhang , Kecheng Guan , Hideto Matsuyama","doi":"10.1016/j.memlet.2025.100101","DOIUrl":"10.1016/j.memlet.2025.100101","url":null,"abstract":"<div><div>A novel strategy was developed to regulate polyamide (PA) membrane morphology and performance by introducing a reactive copolymer, poly(styrene-alt-maleic anhydride) (PSMA), into the polyethersulfone (PES) substrate. The reactive anhydride groups of PSMA first react with piperazine (PIP) monomers, subsequently affecting diffusion and reaction dynamics of the remaining monomers during interfacial polymerization (IP) for PA layer formation. As a result, wrinkled PA morphologies were formed, enhancing the surface roughness and effective filtration area. The wrinkled PA membranes exhibited significantly improved water permeance (up to 19.7 L m<sup>-2</sup> h<sup>-1</sup> bar<sup>-1</sup>) while maintaining comparable rejection rates of 98.7 %, 98.2 %, 85.7 %, 6.1 %, 7.1 % for Na<sub>2</sub>SO<sub>4</sub>, MgSO<sub>4</sub>, MgCl<sub>2</sub>, LiCl, and NaCl, respectively, due to the similar free volume to unmodified membranes. This work offers a promising approach to tailor membrane structure and optimize nanofiltration performance via substrate reactivity engineering.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100101"},"PeriodicalIF":4.9,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-14DOI: 10.1016/j.memlet.2025.100100
Ga Eun Kim , Gyu-Jin Lee , Seoung-Eun Nam , Jinsoo Kim , Sung In Lim , Hyuk Taek Kwon
Here we report that a simple graphene oxide (GO) coating can seal the grain boundary (GB) defects of polycrystalline ZIF-8 membranes and thus improve C3H6/C3H8 separation performance, especially separation factor. The effectiveness of GB defect sealing was investigated in terms of the number of GO coatings, the extent of GB defects in ZIF-8 membranes, and GO coating method (dip-coating under atmospheric pressure vs. dip-coating under vacuum), allowing us to conclude that the strategy can mend ZIF-8 membranes with a wide range of GB defects. Moreover, the GO sealing enhanced the pressure-resistance of a ZIF-8 membrane to some extent. Lastly, the GO-sealed ZIF-8 membrane was thermally stable and the intrinsic transport properties of a ZIF-8 membrane was not influenced by the presence of GO.
{"title":"Sealing grain boundary defects in polycrystalline ZIF-8 membranes by graphene oxide coating","authors":"Ga Eun Kim , Gyu-Jin Lee , Seoung-Eun Nam , Jinsoo Kim , Sung In Lim , Hyuk Taek Kwon","doi":"10.1016/j.memlet.2025.100100","DOIUrl":"10.1016/j.memlet.2025.100100","url":null,"abstract":"<div><div>Here we report that a simple graphene oxide (GO) coating can seal the grain boundary (GB) defects of polycrystalline ZIF-8 membranes and thus improve C<sub>3</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub> separation performance, especially separation factor. The effectiveness of GB defect sealing was investigated in terms of the number of GO coatings, the extent of GB defects in ZIF-8 membranes, and GO coating method (dip-coating under atmospheric pressure vs. dip-coating under vacuum), allowing us to conclude that the strategy can mend ZIF-8 membranes with a wide range of GB defects. Moreover, the GO sealing enhanced the pressure-resistance of a ZIF-8 membrane to some extent. Lastly, the GO-sealed ZIF-8 membrane was thermally stable and the intrinsic transport properties of a ZIF-8 membrane was not influenced by the presence of GO.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100100"},"PeriodicalIF":4.9,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-02DOI: 10.1016/j.memlet.2025.100099
Liat Birnhack , Oren Ben Porat , Ori Fridman , Tiezheng Tong , Razi Epsztein
Understanding the mechanisms of molecular transport in polyamide membranes is imperative to improve their solute-specific selectivity. We explored the partitioning behaviors of water and salts in polyamide membranes to elucidate the role of ion-membrane interactions in the transport. Quartz crystal microbalance (QCM) was employed to quantify the mass uptake at different temperatures and determine partition energies (Ek) for water and salts under two different pH values. Zeta potential and permeability tests were conducted to support the ion-membrane affinity trends observed with QCM and link these trends to ion-ion selectivity. Our results demonstrate a high affinity of water to the polyamide membrane (Ek < 0), with a significant swelling effect attributed to dipole interactions and hydrogen bonding. Ion partitioning revealed distinct differences between monovalent and divalent cations, as well as between kosmotropic and chaotropic anions. Specifically, divalent cations (Ca2+ and Mg2+) exhibited considerably lower partition energies (-0.99 and 0.29 kcal mol-1, respectively) and more efficient charge neutralization, indicating stronger interactions with the membrane compared to monovalent cations (∼2.2 kcal mol-1). The partition energies of the chaotropic iodide and kosmotropic sulphate anions were substantially different (-5.5 and 4.0 kcal mol-1, respectively), likely due to the different tendency of these anions to shed their hydration shell and stick to the polymer. Last, our permeability tests indicate the potential existence of an intrinsic tradeoff between ion partitioning and intrapore diffusion, presumably due to the opposite effects that ion-membrane interactions have on these transport steps. Overall, our work underscores the role of ion-specific interactions in membrane transport and selectivity.
{"title":"Partition energy in polyamide membranes and its link to ion-ion selectivity","authors":"Liat Birnhack , Oren Ben Porat , Ori Fridman , Tiezheng Tong , Razi Epsztein","doi":"10.1016/j.memlet.2025.100099","DOIUrl":"10.1016/j.memlet.2025.100099","url":null,"abstract":"<div><div>Understanding the mechanisms of molecular transport in polyamide membranes is imperative to improve their solute-specific selectivity. We explored the partitioning behaviors of water and salts in polyamide membranes to elucidate the role of ion-membrane interactions in the transport. Quartz crystal microbalance (QCM) was employed to quantify the mass uptake at different temperatures and determine partition energies (<em>E</em><sub>k</sub>) for water and salts under two different pH values. Zeta potential and permeability tests were conducted to support the ion-membrane affinity trends observed with QCM and link these trends to ion-ion selectivity. Our results demonstrate a high affinity of water to the polyamide membrane (<em>E</em><sub>k</sub> < 0), with a significant swelling effect attributed to dipole interactions and hydrogen bonding. Ion partitioning revealed distinct differences between monovalent and divalent cations, as well as between kosmotropic and chaotropic anions. Specifically, divalent cations (Ca<sup>2+</sup> and Mg<sup>2+</sup>) exhibited considerably lower partition energies (-0.99 and 0.29 kcal mol<sup>-1</sup>, respectively) and more efficient charge neutralization, indicating stronger interactions with the membrane compared to monovalent cations (∼2.2 kcal mol<sup>-1</sup>). The partition energies of the chaotropic iodide and kosmotropic sulphate anions were substantially different (-5.5 and 4.0 kcal mol<sup>-1</sup>, respectively), likely due to the different tendency of these anions to shed their hydration shell and stick to the polymer. Last, our permeability tests indicate the potential existence of an intrinsic tradeoff between ion partitioning and intrapore diffusion, presumably due to the opposite effects that ion-membrane interactions have on these transport steps. Overall, our work underscores the role of ion-specific interactions in membrane transport and selectivity.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100099"},"PeriodicalIF":4.9,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-29DOI: 10.1016/j.memlet.2025.100098
Samarpan Deb Majumder , Christopher M. Stafford , Xitong Liu
The molecular layer-by-layer (mLbL) deposition technique enables the fabrication of polyamide-based reverse osmosis membranes with low surface roughness and tunable membrane thickness, but scale-up of the process is challenged by the necessity for rinsing away unreacted monomers after each deposition step. By sensible tuning of monomer concentrations during deposition, we can eliminate the rinsing steps while still producing polyamide membranes with comparable thickness and surface properties. This approach markedly shortens fabrication time and improves reagent efficiency. By measuring the growth rate of the polyamide membrane as a function of deposition cycles and monomer concentration, we demonstrate that we can deliver a more targeted quantity of monomer to the growing film surface while maintaining a linear growth rate profile. Desalination tests reveal that mLbL membranes produced at the lowest monomer concentration (membrane thickness of ≈20 nm) achieved 99.9 % salt rejection within 4 h, while maintaining a flux of 0.98 L m⁻² h⁻¹ bar⁻¹, indicating that the crosslink density of the membrane remains high. This modified mLbL approach significantly reduces membrane fabrication time without compromising performance, offering a path towards scalable production of polyamide-based membranes with controlled thickness and low roughness while prioritizing both time and resource efficiency.
分子层逐层（mLbL）沉积技术可以制造表面粗糙度低、膜厚度可调的聚酰胺基反渗透膜，但在每一步沉积后都需要冲洗掉未反应的单体，这给该工艺的规模化带来了挑战。通过在沉积过程中合理调整单体浓度，我们可以消除冲洗步骤，同时仍然生产具有相当厚度和表面性能的聚酰胺膜。该方法显著缩短了制备时间，提高了试剂效率。通过测量聚酰胺膜的生长速率作为沉积周期和单体浓度的函数，我们证明我们可以在保持线性生长速率的同时向生长的膜表面提供更有针对性的单体数量。脱盐试验表明，在最低单体浓度（膜厚度≈20 nm）下生产的mLbL膜在4小时内达到99.9%的阻盐率，同时保持了0.98 L m（⁻²h -⁻¹巴）的通量，表明膜的交联密度仍然很高。这种改进的mLbL方法在不影响性能的情况下显著缩短了膜的制造时间，为控制厚度和低粗糙度的聚酰胺基膜的规模化生产提供了一条途径，同时优先考虑了时间和资源效率。
{"title":"Rinse-free deposition of molecular layer-by-layer (mLbL) polyamide reverse osmosis membranes","authors":"Samarpan Deb Majumder , Christopher M. Stafford , Xitong Liu","doi":"10.1016/j.memlet.2025.100098","DOIUrl":"10.1016/j.memlet.2025.100098","url":null,"abstract":"<div><div>The molecular layer-by-layer (mLbL) deposition technique enables the fabrication of polyamide-based reverse osmosis membranes with low surface roughness and tunable membrane thickness, but scale-up of the process is challenged by the necessity for rinsing away unreacted monomers after each deposition step. By sensible tuning of monomer concentrations during deposition, we can eliminate the rinsing steps while still producing polyamide membranes with comparable thickness and surface properties. This approach markedly shortens fabrication time and improves reagent efficiency. By measuring the growth rate of the polyamide membrane as a function of deposition cycles and monomer concentration, we demonstrate that we can deliver a more targeted quantity of monomer to the growing film surface while maintaining a linear growth rate profile. Desalination tests reveal that mLbL membranes produced at the lowest monomer concentration (membrane thickness of ≈20 nm) achieved 99.9 % salt rejection within 4 h, while maintaining a flux of 0.98 L m⁻² h⁻¹ bar⁻¹, indicating that the crosslink density of the membrane remains high. This modified mLbL approach significantly reduces membrane fabrication time without compromising performance, offering a path towards scalable production of polyamide-based membranes with controlled thickness and low roughness while prioritizing both time and resource efficiency.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100098"},"PeriodicalIF":4.9,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1016/j.memlet.2025.100097
Anna Malakian, Scott M. Husson
This study is the first to directly visualize and quantify the spatiotemporal dynamics of protein fouling on micropatterned ultrafiltration membranes using in situ confocal laser scanning microscopy (CLSM). In it, we investigated the effectiveness of adding microscale herringbone patterns to ultrafiltration membrane surfaces for reducing protein fouling. Patterns with different geometries were introduced to membrane surfaces by embossing with woven mesh fabrics. Having found earlier that CLSM can provide greater detail for the early (pre-monolayer) stage of fouling, we used CLSM in situ to investigate the protein fouling profiles on as-received and patterned membranes. Labeling the proteins and membranes with different fluorescent probes allowed the spatiotemporal imaging of protein deposition at the early stages of fouling. CLSM images were compared with filtration data to reveal the effect of pattern geometry on protein fouling. Extending the approach to other patterns and multi-component solutions can inform surface modification strategies to control protein fouling in pressure-driven membrane operations.
{"title":"Revealing the spatiotemporal dynamics of protein fouling on micropatterned ultrafiltration membranes by in-situ visualization","authors":"Anna Malakian, Scott M. Husson","doi":"10.1016/j.memlet.2025.100097","DOIUrl":"10.1016/j.memlet.2025.100097","url":null,"abstract":"<div><div>This study is the first to directly visualize and quantify the spatiotemporal dynamics of protein fouling on micropatterned ultrafiltration membranes using in situ confocal laser scanning microscopy (CLSM). In it, we investigated the effectiveness of adding microscale herringbone patterns to ultrafiltration membrane surfaces for reducing protein fouling. Patterns with different geometries were introduced to membrane surfaces by embossing with woven mesh fabrics. Having found earlier that CLSM can provide greater detail for the early (pre-monolayer) stage of fouling, we used CLSM in situ to investigate the protein fouling profiles on as-received and patterned membranes. Labeling the proteins and membranes with different fluorescent probes allowed the spatiotemporal imaging of protein deposition at the early stages of fouling. CLSM images were compared with filtration data to reveal the effect of pattern geometry on protein fouling. Extending the approach to other patterns and multi-component solutions can inform surface modification strategies to control protein fouling in pressure-driven membrane operations.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100097"},"PeriodicalIF":4.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-09DOI: 10.1016/j.memlet.2025.100096
Agathe Lizée, Patrick Loulergue, Anthony Szymczyk
Wetting detection has emerged as a crucial topic of research for enhancing separation processes utilizing membrane contactors. In this letter, we show for the first time how streaming current measurements, via the electrokinetic leakage phenomenon, can provide a new approach to early detection of wetting of hydrophobic porous membranes. Using Tween 20 surfactant solutions of various concentrations (0.0005 – 0.07 mM) and two polyvinylidene fluoride membranes with different pore size (0.22 and 0.45 µm), we demonstrate that wetting is associated with the appearance of an electrokinetic leakage through the porosity of the membrane material, leading to an increase in the streaming current measured experimentally. Monitoring the streaming current over time therefore makes it possible to quantify the wetting kinetics of hydrophobic membranes.
{"title":"Streaming current monitoring as a new approach for early detection of membrane wetting","authors":"Agathe Lizée, Patrick Loulergue, Anthony Szymczyk","doi":"10.1016/j.memlet.2025.100096","DOIUrl":"10.1016/j.memlet.2025.100096","url":null,"abstract":"<div><div>Wetting detection has emerged as a crucial topic of research for enhancing separation processes utilizing membrane contactors. In this letter, we show for the first time how streaming current measurements, via the electrokinetic leakage phenomenon, can provide a new approach to early detection of wetting of hydrophobic porous membranes. Using Tween 20 surfactant solutions of various concentrations (0.0005 – 0.07 mM) and two polyvinylidene fluoride membranes with different pore size (0.22 and 0.45 µm), we demonstrate that wetting is associated with the appearance of an electrokinetic leakage through the porosity of the membrane material, leading to an increase in the streaming current measured experimentally. Monitoring the streaming current over time therefore makes it possible to quantify the wetting kinetics of hydrophobic membranes.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100096"},"PeriodicalIF":4.9,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-14DOI: 10.1016/j.memlet.2025.100094
Simon Wennemaring , Maximilian Meerfeld , Christian J. Linnartz , Matthias Wessling
Electrodialysis (ED) offers a promising solution to address global freshwater shortages and prevent water pollution caused by brackish wastewater from industrial plants. However, local ion concentrations in an opaque ED module cannot currently be measured, even though this information is essential for efficient desalination.
Here, we introduce Magnetic Resonance Imaging (MRI) as an investigative technique to reveal the concentration profiles within ED modules. The signal intensity correlates with the local copper concentration, enabling us to reconstruct the copper distribution inside the module. In our setup, we used a platinum-coated titanium mesh as the anode and a copper mesh as the cathode. These materials are electrochemically stable and minimize disturbances to the tomograph’s magnetic field. In our example case, we applied a current density of 50 mA cm-2 with a flow rate of 0.1 mL min-1. The MRI measurement successfully showed desalination and concentration along the channel length, where the concentration in one diluate channel unexpectedly exhibited a local peak. However, the resolution of the utilized low-field tomograph was not sufficient to image the concentration polarization. Utilizing the proposed desalination module in a high-field tomograph with a higher resolution can deepen our understanding of the in situ process and pave the way for observation-based optimization including the boundary layer at the membranes and unexpected concentration profiles along the channel length.
电渗析（ED）为解决全球淡水短缺和防止工业废水造成的水污染提供了一个有前途的解决方案。然而，不透明ED模块中的局部离子浓度目前还无法测量，尽管这些信息对于高效脱盐至关重要。在这里，我们介绍了磁共振成像（MRI）作为一种调查技术来揭示ED模块内的浓度分布。信号强度与局部铜浓度相关，使我们能够重建模块内的铜分布。在我们的设置中，我们使用镀铂钛网作为阳极，铜网作为阴极。这些材料具有电化学稳定性，对层析成像磁场的干扰最小。在我们的例子中，我们应用的电流密度为50 mA cm-2，流速为0.1 mL min-1。MRI测量成功地显示了沿通道长度的海水淡化和浓度，其中一个稀释通道的浓度出乎意料地出现了局部峰值。然而，所使用的低场层析成像仪的分辨率不足以成像浓偏振。在高场层析成像中使用所提出的脱盐模块可以加深我们对原位过程的理解，并为基于观测的优化铺平道路，包括膜上的边界层和沿着通道长度的意想不到的浓度分布。
{"title":"Visualizing the local ion concentration in electrodialysis cells via magnetic resonance imaging","authors":"Simon Wennemaring , Maximilian Meerfeld , Christian J. Linnartz , Matthias Wessling","doi":"10.1016/j.memlet.2025.100094","DOIUrl":"10.1016/j.memlet.2025.100094","url":null,"abstract":"<div><div>Electrodialysis (ED) offers a promising solution to address global freshwater shortages and prevent water pollution caused by brackish wastewater from industrial plants. However, local ion concentrations in an opaque ED module cannot currently be measured, even though this information is essential for efficient desalination.</div><div>Here, we introduce Magnetic Resonance Imaging (MRI) as an investigative technique to reveal the concentration profiles within ED modules. The signal intensity correlates with the local copper concentration, enabling us to reconstruct the copper distribution inside the module. In our setup, we used a platinum-coated titanium mesh as the anode and a copper mesh as the cathode. These materials are electrochemically stable and minimize disturbances to the tomograph’s magnetic field. In our example case, we applied a current density of 50<!--> <!-->mA<!--> <!-->cm<sup>-2</sup> with a flow rate of 0.1<!--> <!-->mL<!--> <!-->min<sup>-1</sup>. The MRI measurement successfully showed desalination and concentration along the channel length, where the concentration in one diluate channel unexpectedly exhibited a local peak. However, the resolution of the utilized low-field tomograph was not sufficient to image the concentration polarization. Utilizing the proposed desalination module in a high-field tomograph with a higher resolution can deepen our understanding of the <em>in situ</em> process and pave the way for observation-based optimization including the boundary layer at the membranes and unexpected concentration profiles along the channel length.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100094"},"PeriodicalIF":4.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.memlet.2025.100095
Jannik Mehlis , Matthias Wessling
This study investigates water transport behavior through polyelectrolyte membranes under varying pressure gradients using non-equilibrium molecular dynamics (NEMD) simulations. While net water transport is achieved under a pressure gradient, there is also a significant back-diffusion component, challenging the assumption of unidirectional pore flow in such systems. The auto-correlation function of water molecules reveals that water associations are transient and only occur for short periods compared to the overall residence time within the membrane. The correlation of water associations and the water dynamics inside the membrane are not affected by varying pressure differences, which also favors the assumption of a diffusive transport mechanism rather than pore flow. Furthermore, our NEMD simulations provide a detailed analysis of the diffusion-related time lag, revealing an initial transient water transport response and a constant diffusive time lag for all pressure differences. These findings enhance our understanding of water transport mechanisms in membrane systems, underlining the validity of the solution-diffusion model for dense polymeric membranes. The methodology described can be applied to shed light on the discrimination between pore flow and solution-diffusion phenomena.
{"title":"On the diffusive water transport through polyelectrolyte-based membranes","authors":"Jannik Mehlis , Matthias Wessling","doi":"10.1016/j.memlet.2025.100095","DOIUrl":"10.1016/j.memlet.2025.100095","url":null,"abstract":"<div><div>This study investigates water transport behavior through polyelectrolyte membranes under varying pressure gradients using non-equilibrium molecular dynamics (NEMD) simulations. While net water transport is achieved under a pressure gradient, there is also a significant back-diffusion component, challenging the assumption of unidirectional pore flow in such systems. The auto-correlation function of water molecules reveals that water associations are transient and only occur for short periods compared to the overall residence time within the membrane. The correlation of water associations and the water dynamics inside the membrane are not affected by varying pressure differences, which also favors the assumption of a diffusive transport mechanism rather than pore flow. Furthermore, our NEMD simulations provide a detailed analysis of the diffusion-related time lag, revealing an initial transient water transport response and a constant diffusive time lag for all pressure differences. These findings enhance our understanding of water transport mechanisms in membrane systems, underlining the validity of the solution-diffusion model for dense polymeric membranes. The methodology described can be applied to shed light on the discrimination between pore flow and solution-diffusion phenomena.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100095"},"PeriodicalIF":4.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.memlet.2025.100093
Hyungjoon Ji , Wooyoung Choi , Eunji Choi , Yunseong Ji , Minsu Kim , Hwan-Jin Jeon , Dae Woo Kim
Polycrystalline layers of metal-organic frameworks (MOFs) are effective for fabricating high-performance membranes, particularly for gas separation. However, the chemical degradation of these polycrystalline layers has not been extensively studied, though it is reasonable to anticipate severe degradation under harsh conditions. Accordingly, we investigated the mechanisms of morphological deformation and chemical structure changes in zeolite imidazolate framework (ZIF)-8 films under highly reactive conditions using plasma. ZIF-8 was selectively chosen among various MOFs due to its widespread use in gas separation applications and its relatively stable chemical bonds. The plasma generated various reactive species, such as ions and radicals, to accelerate the degradation of the ZIF-8 layer. We observed that reactive Ar ions preferentially etch Zn over C, and fluorine-containing radicals chemically react with Zn to form covalent bonds. Notably, we found that the degradation of the polycrystalline layer initially begins at the grain boundaries. However, as defects form on the grain surfaces, the degradation progresses more extensively within the grains than at the grain boundaries.
{"title":"Degradation of polycrystalline zeolitic imidazolate framework membrane under reactive plasma conditions","authors":"Hyungjoon Ji , Wooyoung Choi , Eunji Choi , Yunseong Ji , Minsu Kim , Hwan-Jin Jeon , Dae Woo Kim","doi":"10.1016/j.memlet.2025.100093","DOIUrl":"10.1016/j.memlet.2025.100093","url":null,"abstract":"<div><div>Polycrystalline layers of metal-organic frameworks (MOFs) are effective for fabricating high-performance membranes, particularly for gas separation. However, the chemical degradation of these polycrystalline layers has not been extensively studied, though it is reasonable to anticipate severe degradation under harsh conditions. Accordingly, we investigated the mechanisms of morphological deformation and chemical structure changes in zeolite imidazolate framework (ZIF)-8 films under highly reactive conditions using plasma. ZIF-8 was selectively chosen among various MOFs due to its widespread use in gas separation applications and its relatively stable chemical bonds. The plasma generated various reactive species, such as ions and radicals, to accelerate the degradation of the ZIF-8 layer. We observed that reactive Ar ions preferentially etch Zn over C, and fluorine-containing radicals chemically react with Zn to form covalent bonds. Notably, we found that the degradation of the polycrystalline layer initially begins at the grain boundaries. However, as defects form on the grain surfaces, the degradation progresses more extensively within the grains than at the grain boundaries.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100093"},"PeriodicalIF":4.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1016/j.memlet.2025.100092
Yuanhui Tang , Yutao Hu , Sisi Wen , Song Lei , Yakai Lin , Li Ding , Haihui Wang
The high purity of Ar is crucial for industrial applications such as steel production, welding, and laboratory use, while the similar physical properties of O2 and Ar make their efficient separation challenging. Existing technologies, such as cryogenic distillation and pressure swing adsorption, are well-established and widely utilized but are hindered by high energy consumption, operational complexity, or limited efficiency. Inspired by the principle that O2 can permeate through the electrolyte as oxygen ions (O2-) in a solid oxide electrolysis cell, for the first time, this study designed and developed an electrochemically-driven tubular inorganic membrane reactor to separate O2/Ar mixtures, achieving high-purity Ar (≥99.99 %). The tubular membrane reactor featured an anode/electrolyte/cathode sandwich structure, offering a compact design particularly suited for gas separation. The reactor employs Ce0.1Gd0.9O2-x (GDC) as the electrolyte, while GDC and Ba0.9Co0.7Fe0.3Nb0.1O3-x are used as the electrode materials. The resulting membrane reactor was compact, defect-free, and capable of producing Ar with a purity of 99.99 %. Additionally, under a constant total current of 0.75 A and an operating temperature of 800 °C, the membrane reactor demonstrated stable performance for over 130 hours, maintaining a Faradaic efficiency exceeding 95 %. This study anticipates that the membrane reactor can serve as an effective and practical solution for separating O2/Ar mixtures, particularly at low O2 partial pressures.
{"title":"Electrochemically-driven solid oxide tubular membrane reactor for efficient separation of oxygen and argon","authors":"Yuanhui Tang , Yutao Hu , Sisi Wen , Song Lei , Yakai Lin , Li Ding , Haihui Wang","doi":"10.1016/j.memlet.2025.100092","DOIUrl":"10.1016/j.memlet.2025.100092","url":null,"abstract":"<div><div>The high purity of Ar is crucial for industrial applications such as steel production, welding, and laboratory use, while the similar physical properties of O<sub>2</sub> and Ar make their efficient separation challenging. Existing technologies, such as cryogenic distillation and pressure swing adsorption, are well-established and widely utilized but are hindered by high energy consumption, operational complexity, or limited efficiency. Inspired by the principle that O<sub>2</sub> can permeate through the electrolyte as oxygen ions (O<sup>2-</sup>) in a solid oxide electrolysis cell, for the first time, this study designed and developed an electrochemically-driven tubular inorganic membrane reactor to separate O<sub>2</sub>/Ar mixtures, achieving high-purity Ar (≥99.99 %). The tubular membrane reactor featured an anode/electrolyte/cathode sandwich structure, offering a compact design particularly suited for gas separation. The reactor employs Ce<sub>0.1</sub>Gd<sub>0.9</sub>O<sub>2-x</sub> (GDC) as the electrolyte, while GDC and Ba<sub>0.9</sub>Co<sub>0.7</sub>Fe<sub>0.3</sub>Nb<sub>0.1</sub>O<sub>3-x</sub> are used as the electrode materials. The resulting membrane reactor was compact, defect-free, and capable of producing Ar with a purity of 99.99 %. Additionally, under a constant total current of 0.75 A and an operating temperature of 800 °C, the membrane reactor demonstrated stable performance for over 130 hours, maintaining a Faradaic efficiency exceeding 95 %. This study anticipates that the membrane reactor can serve as an effective and practical solution for separating O<sub>2</sub>/Ar mixtures, particularly at low O<sub>2</sub> partial pressures.</div></div>","PeriodicalId":100805,"journal":{"name":"Journal of Membrane Science Letters","volume":"5 1","pages":"Article 100092"},"PeriodicalIF":4.9,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143292745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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