Pub Date : 2024-08-06DOI: 10.3390/membranes14080171
Daniel C M Cavalcante, Hortência L F Magalhães, Severino R Farias Neto, Ricardo S Gomez, João M P Q Delgado, Antonio G B Lima, Danielle B T Vasconcelos, Márcio J V Silva, Daniel O Farias, Suelyn F A M Queiroz, Antonio C Q Santos, Thâmmara L H Tito, Emmanuel F M Silva
A conventional hydrocyclones is a versatile equipment with a high processing capacity and low maintenance cost. Currently, several studies aim to alter the typical structure of the conventional hydrocyclone in order to modify its performance and purpose. For this, filtering hydrocyclones have emerged, where a porous membrane replaces the conic or cylindrical wall. During the operation of this equipment, in addition to the traditionally observed streams (feed, underflow, and overflow), there is a liquid stream resulting from the filtration process, commonly referred to as filtrate. This work proposes to numerically investigate the solid particle/liquid water separation process in a filtering hydrocyclone using the commercial software Ansys CFX® 15.0. The proposed mathematical model for the study considers three-dimensional, steady state and turbulent flow, using the Eulerian-Eulerian approach and the Shear Stress Transport (SST) turbulence model. This study presents and analyzes the volume fraction, velocity, and pressure fields, along with flowlines and velocity profiles. The results indicate that the proposed model effectively captures the fluid dynamic behavior within the filtering hydrocyclone, highlighting higher pressures near the porous membrane and a higher concentration of solid particles in the conical region, with water being more concentrated in the cylindrical part of the hydrocyclone. Additionally, the findings show that the volumetric flow rate of the filtrate significantly influences the internal flow dynamics, with conventional hydrocyclones demonstrating higher pressure gradients compared to the proposed filtering hydrocyclone.
{"title":"Hydrodynamic Evaluation of a Filtering Hydrocyclone for Solid Particle/Water Separation.","authors":"Daniel C M Cavalcante, Hortência L F Magalhães, Severino R Farias Neto, Ricardo S Gomez, João M P Q Delgado, Antonio G B Lima, Danielle B T Vasconcelos, Márcio J V Silva, Daniel O Farias, Suelyn F A M Queiroz, Antonio C Q Santos, Thâmmara L H Tito, Emmanuel F M Silva","doi":"10.3390/membranes14080171","DOIUrl":"10.3390/membranes14080171","url":null,"abstract":"<p><p>A conventional hydrocyclones is a versatile equipment with a high processing capacity and low maintenance cost. Currently, several studies aim to alter the typical structure of the conventional hydrocyclone in order to modify its performance and purpose. For this, filtering hydrocyclones have emerged, where a porous membrane replaces the conic or cylindrical wall. During the operation of this equipment, in addition to the traditionally observed streams (feed, underflow, and overflow), there is a liquid stream resulting from the filtration process, commonly referred to as filtrate. This work proposes to numerically investigate the solid particle/liquid water separation process in a filtering hydrocyclone using the commercial software Ansys CFX<sup>®</sup> 15.0. The proposed mathematical model for the study considers three-dimensional, steady state and turbulent flow, using the Eulerian-Eulerian approach and the Shear Stress Transport (SST) turbulence model. This study presents and analyzes the volume fraction, velocity, and pressure fields, along with flowlines and velocity profiles. The results indicate that the proposed model effectively captures the fluid dynamic behavior within the filtering hydrocyclone, highlighting higher pressures near the porous membrane and a higher concentration of solid particles in the conical region, with water being more concentrated in the cylindrical part of the hydrocyclone. Additionally, the findings show that the volumetric flow rate of the filtrate significantly influences the internal flow dynamics, with conventional hydrocyclones demonstrating higher pressure gradients compared to the proposed filtering hydrocyclone.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11356502/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-31DOI: 10.3390/membranes14080169
Minjoo Song, Jin Yong Park
Microplastics (MPs), which are defined as plastics with a size of less than 5 mm, cannot be treated completely in wastewater treatment plants (WWTPs) and discharged to a water body because they are too small in size. It has been reported that MPs can have adverse effects on human beings and water ecosystems. There is a need to combine existing drinking water treatment plants (DWTPs) and WWTPs with the traditional treatment process and technology with high removal efficiency of MPs or to develop a new technology to separate MPs from water and wastewater. In this study, the effects of MPs (polyethylene (PE), 125 μm) and organic matter (humic acid) were researched in a hybrid treatment process of ceramic microfiltration (MF) and photocatalyst (TiO2)-mounted polyether sulfone (PES) spheres with air backwashing. The roles of the MF, photooxidation, and adsorption of PES spheres were confirmed in a single MF process (MF), an MF process with UV irradiation (MF+UV), MF and PES sphere adsorption without UV irradiation (MF+PES), and a hybrid process incorporating MF and PES spheres with UV irradiation (MF+PES+UV). The impact of the air backwashing cycle (filtration time, FT) on filtration characteristics and treatment efficiencies in the hybrid process was studied. In the MF process, membrane fouling increased with increasing organic matter (HA, humic acid). The treatment efficiency of MPs increased; however, that of dissolved organic matter (DOM) decreased with increasing HA. As MPs increased, the membrane fouling decreased; however, total filtration volume (VT) remained almost constant. The treatment efficiency of MPs increased a little, and that of DOM showed a dropping trend. In the hybrid process, the membrane fouling was controlled via the adsorption and UV photooxidation of the PES spheres, and the DOM treatment efficiency increased by combining processes from MF to MF+PES+UV. The optimal FT was 10 min at BT 10 s in this hybrid process. The results could be applied to separate MPs effectively in DWTPs/WWTPs.
微塑料(MPs)是指尺寸小于 5 毫米的塑料,由于尺寸太小,无法在污水处理厂(WWTPs)中完全处理并排放到水体中。据报道,MPs 会对人类和水生态系统造成不利影响。因此,有必要将现有的饮用水处理厂(DWTP)和污水处理厂与传统的处理工艺和技术相结合,以实现对 MPs 的高效去除,或者开发一种新技术,将 MPs 从水和废水中分离出来。本研究研究了陶瓷微滤(MF)和光催化剂(TiO2)安装的聚醚砜(PES)球体与空气反冲洗的混合处理工艺对 MPs(聚乙烯(PE),125 μm)和有机物(腐植酸)的影响。在单一微滤工艺(MF)、带有紫外线照射的微滤工艺(MF+UV)、不带有紫外线照射的微滤和聚醚砜球吸附工艺(MF+PES)以及带有紫外线照射的微滤和聚醚砜球混合工艺(MF+PES+UV)中,确认了微滤、光氧化和聚醚砜球吸附的作用。在混合工艺中,研究了空气反冲洗周期(过滤时间,FT)对过滤特性和处理效率的影响。在 MF 工艺中,膜污垢随着有机物(HA、腐殖酸)的增加而增加。MPs 的处理效率提高了,但溶解有机物(DOM)的处理效率却随着 HA 的增加而降低。随着 MPs 的增加,膜污垢减少;但总过滤量(VT)几乎保持不变。MPs 的处理效率略有提高,而 DOM 的处理效率呈下降趋势。在混合工艺中,通过 PES 球体的吸附和紫外光氧化作用控制了膜污垢,并通过从 MF 到 MF+PES+UV 的组合工艺提高了 DOM 的处理效率。在这种混合工艺中,最佳的 FT 为 10 分钟,BT 为 10 秒。该结果可用于有效分离污水处理厂/污水处理厂中的 MPs。
{"title":"Removal of Microplastics in a Hybrid Treatment Process of Ceramic Microfiltration and Photocatalyst-Mounted PES Spheres with Air Backwashing.","authors":"Minjoo Song, Jin Yong Park","doi":"10.3390/membranes14080169","DOIUrl":"10.3390/membranes14080169","url":null,"abstract":"<p><p>Microplastics (MPs), which are defined as plastics with a size of less than 5 mm, cannot be treated completely in wastewater treatment plants (WWTPs) and discharged to a water body because they are too small in size. It has been reported that MPs can have adverse effects on human beings and water ecosystems. There is a need to combine existing drinking water treatment plants (DWTPs) and WWTPs with the traditional treatment process and technology with high removal efficiency of MPs or to develop a new technology to separate MPs from water and wastewater. In this study, the effects of MPs (polyethylene (PE), 125 μm) and organic matter (humic acid) were researched in a hybrid treatment process of ceramic microfiltration (MF) and photocatalyst (TiO<sub>2</sub>)-mounted polyether sulfone (PES) spheres with air backwashing. The roles of the MF, photooxidation, and adsorption of PES spheres were confirmed in a single MF process (MF), an MF process with UV irradiation (MF+UV), MF and PES sphere adsorption without UV irradiation (MF+PES), and a hybrid process incorporating MF and PES spheres with UV irradiation (MF+PES+UV). The impact of the air backwashing cycle (filtration time, FT) on filtration characteristics and treatment efficiencies in the hybrid process was studied. In the MF process, membrane fouling increased with increasing organic matter (HA, humic acid). The treatment efficiency of MPs increased; however, that of dissolved organic matter (DOM) decreased with increasing HA. As MPs increased, the membrane fouling decreased; however, total filtration volume (V<sub>T</sub>) remained almost constant. The treatment efficiency of MPs increased a little, and that of DOM showed a dropping trend. In the hybrid process, the membrane fouling was controlled via the adsorption and UV photooxidation of the PES spheres, and the DOM treatment efficiency increased by combining processes from MF to MF+PES+UV. The optimal FT was 10 min at BT 10 s in this hybrid process. The results could be applied to separate MPs effectively in DWTPs/WWTPs.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11356475/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-30DOI: 10.3390/membranes14080168
Shu Liu, Kiran Kumar, Tracey Bell, Ayyalusamy Ramamoorthy, David Van Winkle, Steven Lenhert
Lipids have not traditionally been considered likely candidates for catalyzing reactions in biological systems. However, there is significant evidence that aggregates of amphiphilic compounds are capable of catalyzing reactions in synthetic organic chemistry. Here, we demonstrate the potential for the hydrophobic region of a lipid bilayer to provide an environment suitable for catalysis by means of a lipid aggregate capable of speeding up a chemical reaction. By bringing organic molecules into the nonpolar or hydrophobic region of a lipid bilayer, reactions can be catalyzed by individual or collections of small, nonpolar, or amphiphilic molecules. We demonstrate this concept by the ester hydrolysis of calcein-AM to produce a fluorescent product, which is a widely used assay for esterase activity in cells. The reaction was first carried out in a two-phase octanol-water system, with the organic phase containing the cationic amphiphiles cetyltrimethylammonium bromide (CTAB) or octadecylamine. The octanol phase was then replaced with phospholipid vesicles in water, where the reaction was also found to be carried out. The reaction was monitored using quantitative fluorescence, which revealed catalytic turnover numbers on a scale of 10-7 to 10-8 s-1 for each system, which is much slower than enzymatic catalysis. The reaction product was characterized by 1H-NMR measurements, which were consistent with ester hydrolysis. The implications of thinking about lipids and lipid aggregates as catalytic entities are discussed in the context of biochemistry, pharmacology, and synthetic biology.
{"title":"Lipid-Based Catalysis Demonstrated by Bilayer-Enabled Ester Hydrolysis.","authors":"Shu Liu, Kiran Kumar, Tracey Bell, Ayyalusamy Ramamoorthy, David Van Winkle, Steven Lenhert","doi":"10.3390/membranes14080168","DOIUrl":"10.3390/membranes14080168","url":null,"abstract":"<p><p>Lipids have not traditionally been considered likely candidates for catalyzing reactions in biological systems. However, there is significant evidence that aggregates of amphiphilic compounds are capable of catalyzing reactions in synthetic organic chemistry. Here, we demonstrate the potential for the hydrophobic region of a lipid bilayer to provide an environment suitable for catalysis by means of a lipid aggregate capable of speeding up a chemical reaction. By bringing organic molecules into the nonpolar or hydrophobic region of a lipid bilayer, reactions can be catalyzed by individual or collections of small, nonpolar, or amphiphilic molecules. We demonstrate this concept by the ester hydrolysis of calcein-AM to produce a fluorescent product, which is a widely used assay for esterase activity in cells. The reaction was first carried out in a two-phase octanol-water system, with the organic phase containing the cationic amphiphiles cetyltrimethylammonium bromide (CTAB) or octadecylamine. The octanol phase was then replaced with phospholipid vesicles in water, where the reaction was also found to be carried out. The reaction was monitored using quantitative fluorescence, which revealed catalytic turnover numbers on a scale of 10-7 to 10-8 s<sup>-1</sup> for each system, which is much slower than enzymatic catalysis. The reaction product was characterized by <sup>1</sup>H-NMR measurements, which were consistent with ester hydrolysis. The implications of thinking about lipids and lipid aggregates as catalytic entities are discussed in the context of biochemistry, pharmacology, and synthetic biology.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11356346/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-30DOI: 10.3390/membranes14080167
Peter Jr Leszczynski, Siamak Lashkari, Boguslaw Kruczek
The time-lag method is commonly used to determine membrane permeability, diffusivity and solubility in a single gas permeation experiment in a constant volume system. An unwritten assumption on which this method relies is that there is no resistance to gas accumulation in the downstream receiver of the system. However, this is not the case, even with the specially designed receiver used in this study when, in addition to tubing, the receiver utilizes an additional accumulation tank. The resistance to gas accumulation originates from a finite diffusivity (Knudsen diffusion) of gases in tubing, which are magnified by "resistance-free" accumulation tank(s). As a result of the resistance to gas accumulation, the time lag of the membrane is underestimated, which leads to an overestimation of gas diffusivity in the membrane. The experimentally predicted resistances in different configurations of the receiver, expressed by the difference in the time lag at two different receiver locations, were several times greater than the theoretically predicted values. A high molecular PPO membrane was used to demonstrate this effect. The time lags measured at different locations differed by as much as 30%. The diffusivity of nitrogen in a PPO of 4.04 × 10-12 m2/s determined at the optimum configuration of the receiver is at least 50% lower than the literature-reported values.
{"title":"Revisiting the Effect of the Resistance to Gas Accumulation in Constant Volume Systems on the Membrane Time Lag.","authors":"Peter Jr Leszczynski, Siamak Lashkari, Boguslaw Kruczek","doi":"10.3390/membranes14080167","DOIUrl":"10.3390/membranes14080167","url":null,"abstract":"<p><p>The time-lag method is commonly used to determine membrane permeability, diffusivity and solubility in a single gas permeation experiment in a constant volume system. An unwritten assumption on which this method relies is that there is no resistance to gas accumulation in the downstream receiver of the system. However, this is not the case, even with the specially designed receiver used in this study when, in addition to tubing, the receiver utilizes an additional accumulation tank. The resistance to gas accumulation originates from a finite diffusivity (Knudsen diffusion) of gases in tubing, which are magnified by \"resistance-free\" accumulation tank(s). As a result of the resistance to gas accumulation, the time lag of the membrane is underestimated, which leads to an overestimation of gas diffusivity in the membrane. The experimentally predicted resistances in different configurations of the receiver, expressed by the difference in the time lag at two different receiver locations, were several times greater than the theoretically predicted values. A high molecular PPO membrane was used to demonstrate this effect. The time lags measured at different locations differed by as much as 30%. The diffusivity of nitrogen in a PPO of 4.04 × 10<sup>-12</sup> m<sup>2</sup>/s determined at the optimum configuration of the receiver is at least 50% lower than the literature-reported values.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11355954/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, nanofiltration experiments using synthetic solutions containing acetate, butyrate, and lactate are carried out to assess the impact of the feed composition, i.e., feed concentration and feed proportions, on the separation factor of couples of solutes in binary and ternary solutions. In binary solutions, no influence of the solute proportions in the feed was pointed out, whatever the couple of solutes. The separation factor of acetate/butyrate and acetate/lactate was found to decrease with increasing feed concentration, while that of lactate/butyrate remained constant. The separation factors of acetate/lactate and lactate/butyrate were identical in ternary solutions compared to binary ones, showing no impact of the addition of the third solute. In ternary solutions, the presence of lactate decreased the separation factor of acetate/butyrate, but this decrease was not influenced by the proportion of lactate.
{"title":"Influence of Feed Composition on the Separation Factor during Nanofiltration of Organic Acids.","authors":"Gustavo Tottoli, Sylvain Galier, Hélène Roux-de Balmann","doi":"10.3390/membranes14080166","DOIUrl":"10.3390/membranes14080166","url":null,"abstract":"<p><p>In this study, nanofiltration experiments using synthetic solutions containing acetate, butyrate, and lactate are carried out to assess the impact of the feed composition, i.e., feed concentration and feed proportions, on the separation factor of couples of solutes in binary and ternary solutions. In binary solutions, no influence of the solute proportions in the feed was pointed out, whatever the couple of solutes. The separation factor of acetate/butyrate and acetate/lactate was found to decrease with increasing feed concentration, while that of lactate/butyrate remained constant. The separation factors of acetate/lactate and lactate/butyrate were identical in ternary solutions compared to binary ones, showing no impact of the addition of the third solute. In ternary solutions, the presence of lactate decreased the separation factor of acetate/butyrate, but this decrease was not influenced by the proportion of lactate.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11356361/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-20DOI: 10.3390/membranes14070160
Chhabilal Regmi, Yuwaraj K Kshetri, S Ranil Wickramasinghe
The development of an ideal membrane for membrane distillation (MD) is of the utmost importance. Enhancing the efficiency of MD by adding nanoparticles to or onto a membrane's surface has drawn considerable attention from the scientific community. It is crucial to thoroughly examine state-of-the-art nanomaterials-enabled MD membranes with desirable properties, as they greatly enhance the efficiency and reliability of the MD process. This, in turn, opens up opportunities for achieving a sustainable water-energy-environment nexus. By introducing carbon-based nanomaterials into the membrane's structure, the membrane gains excellent separation abilities, resistance to various feed waters, and a longer lifespan. Additionally, the use of carbon-based nanomaterials in MD has led to improved membrane performance characteristics such as increased permeability and a reduced fouling propensity. These nanomaterials have also enabled novel membrane capabilities like in situ foulant degradation and localized heat generation. Therefore, this review offers an overview of how the utilization of different carbon-based nanomaterials in membrane synthesis impacts the membrane characteristics, particularly the liquid entry pressure (LEP), hydrophobicity, porosity, and membrane permeability, as well as reduced fouling, thereby advancing the MD technology for water treatment processes. Furthermore, this review also discusses the development, challenges, and research opportunities that arise from these findings.
{"title":"Carbon-Based Nanocomposite Membranes for Membrane Distillation: Progress, Problems and Future Prospects.","authors":"Chhabilal Regmi, Yuwaraj K Kshetri, S Ranil Wickramasinghe","doi":"10.3390/membranes14070160","DOIUrl":"10.3390/membranes14070160","url":null,"abstract":"<p><p>The development of an ideal membrane for membrane distillation (MD) is of the utmost importance. Enhancing the efficiency of MD by adding nanoparticles to or onto a membrane's surface has drawn considerable attention from the scientific community. It is crucial to thoroughly examine state-of-the-art nanomaterials-enabled MD membranes with desirable properties, as they greatly enhance the efficiency and reliability of the MD process. This, in turn, opens up opportunities for achieving a sustainable water-energy-environment nexus. By introducing carbon-based nanomaterials into the membrane's structure, the membrane gains excellent separation abilities, resistance to various feed waters, and a longer lifespan. Additionally, the use of carbon-based nanomaterials in MD has led to improved membrane performance characteristics such as increased permeability and a reduced fouling propensity. These nanomaterials have also enabled novel membrane capabilities like in situ foulant degradation and localized heat generation. Therefore, this review offers an overview of how the utilization of different carbon-based nanomaterials in membrane synthesis impacts the membrane characteristics, particularly the liquid entry pressure (LEP), hydrophobicity, porosity, and membrane permeability, as well as reduced fouling, thereby advancing the MD technology for water treatment processes. Furthermore, this review also discusses the development, challenges, and research opportunities that arise from these findings.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11278710/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-20DOI: 10.3390/membranes14070161
Ishan Ghai
The alarming rise of antibiotic resistance in Gram-negative bacteria has emerged as a major global health challenge. A key factor contributing to this crisis is the low permeability of the bacterial outer membrane, which acts as a barrier that prevents antibiotics from entering the cell. Protein channels embedded in this outer membrane selectively regulate the influx of hydrophilic compounds, including antibiotics. To combat antibiotic resistance, understanding the molecular mechanisms governing antibiotic permeability through bacterial membrane channels is crucial. This knowledge is key towards elucidating their roles in studing antibiotic resistance. By compiling and analysing the flux data from multiple electrophysiological reversal potential experimental studies, which involves measuring zero-current potentials and the corresponding single-channel conductance, we can calculate the flux of charged antibiotics/compounds across different Gram-negative bacterial outer membrane channels. Through this comprehensive synthesis, this review aims to advance our understanding and stimulate discussions about the physicochemical factors influencing the flux of antibiotics through bacterial membrane protein channels, ultimately enhancing our knowledge in this area.
{"title":"Electrophysiological Insights into Antibiotic Translocation and Resistance: The Impact of Outer Membrane Proteins.","authors":"Ishan Ghai","doi":"10.3390/membranes14070161","DOIUrl":"10.3390/membranes14070161","url":null,"abstract":"<p><p>The alarming rise of antibiotic resistance in Gram-negative bacteria has emerged as a major global health challenge. A key factor contributing to this crisis is the low permeability of the bacterial outer membrane, which acts as a barrier that prevents antibiotics from entering the cell. Protein channels embedded in this outer membrane selectively regulate the influx of hydrophilic compounds, including antibiotics. To combat antibiotic resistance, understanding the molecular mechanisms governing antibiotic permeability through bacterial membrane channels is crucial. This knowledge is key towards elucidating their roles in studing antibiotic resistance. By compiling and analysing the flux data from multiple electrophysiological reversal potential experimental studies, which involves measuring zero-current potentials and the corresponding single-channel conductance, we can calculate the flux of charged antibiotics/compounds across different Gram-negative bacterial outer membrane channels. Through this comprehensive synthesis, this review aims to advance our understanding and stimulate discussions about the physicochemical factors influencing the flux of antibiotics through bacterial membrane protein channels, ultimately enhancing our knowledge in this area.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11279362/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-19DOI: 10.3390/membranes14070159
Wirginia Tomczak, Piotr Woźniak, Marek Gryta, Joanna Grzechulska-Damszel, Monika Daniluk
Car wash wastewaters (CWWs) contain various pollutants with different contents. Hence, selecting an appropriate process for their treatment is a great challenge. Undoubtedly, the ultrafiltration (UF) process is one of the most interesting and reliable choices. Therefore, the main aim of the current study was to investigate the performance of the UF membranes used for the long-term treatment of real CWWs. For this purpose, two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) values equal to 10 and 100 kDa were applied. As expected, a significant decrease in the permeate flux during the UF run was observed. However, it was immediately demonstrated that the systematic cleaning of membranes (every day) with Insect agent (pH = 11.5) prevented a further decline in the process's performance. In addition, this study focused on the relative flux during the process run with breaks lasting a few days when the UF installation was filled with distilled water. The results of this research indicated that aqueous media favor microorganism adherence to the surface which leads to the formation of biofilms inside processing installations. As a consequence, many attempts have been made to restore the initial membrane performance. It has been found that the application of several chemical agents is required. More precisely, the use of an Insect solution, P3 Ultrasil 11 agent, and phosphoric acid increases the relative flux to a value of 0.8. Finally, it has been indicated that the membranes used in this work are resistant to the long-term exposure to bacteria and chemical agents. However, during the separation of CWWs for the membrane with an MWCO of 10 kDa, a lesser fouling influence and higher effectiveness of cleaning were obtained. Finally, the present study demonstrates a novel analysis and innovative implications towards applying the UF process for the CWW treatment.
{"title":"Cleaning of Ultrafiltration Membranes: Long-Term Treatment of Car Wash Wastewater as a Case Study.","authors":"Wirginia Tomczak, Piotr Woźniak, Marek Gryta, Joanna Grzechulska-Damszel, Monika Daniluk","doi":"10.3390/membranes14070159","DOIUrl":"10.3390/membranes14070159","url":null,"abstract":"<p><p>Car wash wastewaters (CWWs) contain various pollutants with different contents. Hence, selecting an appropriate process for their treatment is a great challenge. Undoubtedly, the ultrafiltration (UF) process is one of the most interesting and reliable choices. Therefore, the main aim of the current study was to investigate the performance of the UF membranes used for the long-term treatment of real CWWs. For this purpose, two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) values equal to 10 and 100 kDa were applied. As expected, a significant decrease in the permeate flux during the UF run was observed. However, it was immediately demonstrated that the systematic cleaning of membranes (every day) with Insect agent (pH = 11.5) prevented a further decline in the process's performance. In addition, this study focused on the relative flux during the process run with breaks lasting a few days when the UF installation was filled with distilled water. The results of this research indicated that aqueous media favor microorganism adherence to the surface which leads to the formation of biofilms inside processing installations. As a consequence, many attempts have been made to restore the initial membrane performance. It has been found that the application of several chemical agents is required. More precisely, the use of an Insect solution, P3 Ultrasil 11 agent, and phosphoric acid increases the relative flux to a value of 0.8. Finally, it has been indicated that the membranes used in this work are resistant to the long-term exposure to bacteria and chemical agents. However, during the separation of CWWs for the membrane with an MWCO of 10 kDa, a lesser fouling influence and higher effectiveness of cleaning were obtained. Finally, the present study demonstrates a novel analysis and innovative implications towards applying the UF process for the CWW treatment.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11278524/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-07-17DOI: 10.3390/membranes14070158
Mohammad A Afzal, Joshua Peles, Andrew L Zydney
The performance of virus filters is often determined by the extent of protein fouling, which can affect both filtrate flux and virus retention. However, the mechanisms governing changes in virus retention in the presence of proteins are still not well understood. The objective of this work was to examine the effect of proteins on virus retention by both asymmetric (Viresolve® NFP and Viresolve® Pro) and relatively homogeneous (Ultipor® DV20 and PegasusTM SV4) virus filtration membranes. Experiments were performed with bacteriophage ϕX174 as a model parvovirus and human serum immunoglobulin G (hIgG) as a model protein. The virus retention in 1 g/L hIgG solutions was consistently less than that in a protein-free buffer solution by between 1 to 3 logs for the different virus filters. The virus retention profiles for the two homogeneous membranes were very similar, with the virus retention being highly correlated with the extent of flux decline. Membranes prefouled with hIgG and then challenged with phages also showed much lower virus retention, demonstrating the importance of membrane fouling; the one exception was the Viresolve® Pro membrane, which showed a similar virus retention for the prefouled and pristine membranes. Experiments in which the protein was filtered after the virus challenge demonstrated that hIgG can displace previously captured viruses from within a filter. The magnitude of these effects significantly varied for the different virus filters, likely due to differences in membrane morphology, pore size distribution, and chemistry, providing important insights into the development/application of virus filtration in bioprocessing.
{"title":"Comparative Analysis of the Impact of Protein on Virus Retention for Different Virus Removal Filters.","authors":"Mohammad A Afzal, Joshua Peles, Andrew L Zydney","doi":"10.3390/membranes14070158","DOIUrl":"10.3390/membranes14070158","url":null,"abstract":"<p><p>The performance of virus filters is often determined by the extent of protein fouling, which can affect both filtrate flux and virus retention. However, the mechanisms governing changes in virus retention in the presence of proteins are still not well understood. The objective of this work was to examine the effect of proteins on virus retention by both asymmetric (Viresolve<sup>®</sup> NFP and Viresolve<sup>®</sup> Pro) and relatively homogeneous (Ultipor<sup>®</sup> DV20 and Pegasus<sup>TM</sup> SV4) virus filtration membranes. Experiments were performed with bacteriophage ϕX174 as a model parvovirus and human serum immunoglobulin G (hIgG) as a model protein. The virus retention in 1 g/L hIgG solutions was consistently less than that in a protein-free buffer solution by between 1 to 3 logs for the different virus filters. The virus retention profiles for the two homogeneous membranes were very similar, with the virus retention being highly correlated with the extent of flux decline. Membranes prefouled with hIgG and then challenged with phages also showed much lower virus retention, demonstrating the importance of membrane fouling; the one exception was the Viresolve<sup>®</sup> Pro membrane, which showed a similar virus retention for the prefouled and pristine membranes. Experiments in which the protein was filtered after the virus challenge demonstrated that hIgG can displace previously captured viruses from within a filter. The magnitude of these effects significantly varied for the different virus filters, likely due to differences in membrane morphology, pore size distribution, and chemistry, providing important insights into the development/application of virus filtration in bioprocessing.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11278833/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-06-30DOI: 10.3390/membranes14070148
Jinwu Wang, Syed Comail Abbas, Ling Li, Colleen C Walker, Yonghao Ni, Zhiyong Cai
Membranes are a selective barrier that allows certain species (molecules and ions) to pass through while blocking others. Some rely on size exclusion, where larger molecules get stuck while smaller ones permeate through. Others use differences in charge or polarity to attract and repel specific species. Membranes can purify air and water by allowing only air and water molecules to pass through, while preventing contaminants such as microorganisms and particles, or to separate a target gas or vapor, such as H2 and CO2, from other gases. The higher the flux and selectivity, the better a material is for membranes. The desirable performance can be tuned through material type (polymers, ceramics, and biobased materials), microstructure (porosity and tortuosity), and surface chemistry. Most membranes are made from plastic from petroleum-based resources, contributing to global climate change and plastic pollution. Cellulose can be an alternative sustainable resource for making renewable membranes. Cellulose exists in plant cell walls as natural fibers, which can be broken down into smaller components such as cellulose fibrils, nanofibrils, nanocrystals, and cellulose macromolecules through mechanical and chemical processing. Membranes made from reassembling these particles and molecules have variable pore architecture, porosity, and separation properties and, therefore, have a wide range of applications in nano-, micro-, and ultrafiltration and forward osmosis. Despite their advantages, cellulose membranes face some challenges. Improving the selectivity of membranes for specific molecules often comes at the expense of permeability. The stability of cellulose membranes in harsh environments or under continuous operation needs further improvement. Research is ongoing to address these challenges and develop advanced cellulose membranes with enhanced performance. This article reviews the microstructures, fabrication methods, and potential applications of cellulose membranes, providing some critical insights into processing-structure-property relationships for current state-of-the-art cellulosic membranes that could be used to improve their performance.
{"title":"Cellulose Membranes: Synthesis and Applications for Water and Gas Separation and Purification.","authors":"Jinwu Wang, Syed Comail Abbas, Ling Li, Colleen C Walker, Yonghao Ni, Zhiyong Cai","doi":"10.3390/membranes14070148","DOIUrl":"10.3390/membranes14070148","url":null,"abstract":"<p><p>Membranes are a selective barrier that allows certain species (molecules and ions) to pass through while blocking others. Some rely on size exclusion, where larger molecules get stuck while smaller ones permeate through. Others use differences in charge or polarity to attract and repel specific species. Membranes can purify air and water by allowing only air and water molecules to pass through, while preventing contaminants such as microorganisms and particles, or to separate a target gas or vapor, such as H<sub>2</sub> and CO<sub>2</sub>, from other gases. The higher the flux and selectivity, the better a material is for membranes. The desirable performance can be tuned through material type (polymers, ceramics, and biobased materials), microstructure (porosity and tortuosity), and surface chemistry. Most membranes are made from plastic from petroleum-based resources, contributing to global climate change and plastic pollution. Cellulose can be an alternative sustainable resource for making renewable membranes. Cellulose exists in plant cell walls as natural fibers, which can be broken down into smaller components such as cellulose fibrils, nanofibrils, nanocrystals, and cellulose macromolecules through mechanical and chemical processing. Membranes made from reassembling these particles and molecules have variable pore architecture, porosity, and separation properties and, therefore, have a wide range of applications in nano-, micro-, and ultrafiltration and forward osmosis. Despite their advantages, cellulose membranes face some challenges. Improving the selectivity of membranes for specific molecules often comes at the expense of permeability. The stability of cellulose membranes in harsh environments or under continuous operation needs further improvement. Research is ongoing to address these challenges and develop advanced cellulose membranes with enhanced performance. This article reviews the microstructures, fabrication methods, and potential applications of cellulose membranes, providing some critical insights into processing-structure-property relationships for current state-of-the-art cellulosic membranes that could be used to improve their performance.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"14 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11279174/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}