Different Types Of Membranes Research Articles

Resorbable engineered barrier membranes for oral surgery applications.

Population aging, reduced economic capacity, and neglecting the treatments for oral pathologies, are the main causal factors for about 3 billion individuals who are suffering from partial/total edentulism or alveolar bone resorption: thus, the demand for dental implants is increasingly growing. To achieve a good prognosis for implant-supported restorations, adequate peri-implant bone volume is mandatory. The Guided Bone Regeneration (GBR) technique is one of the most applied methods for alveolar bone reconstruction and treatment of peri-implant bone deficiencies. This technique involves the use of different types of membranes in association with some bone substitutes (autologous, homologous, or heterologous). However, time for bone regeneration is often too long and the bone quality is not simply predictable. This study aims at engineering and evaluating the efficacy of modified barrier membranes, enhancing their bioactivity for improved alveolar bone tissue regeneration. We investigated membranes functionalized with chitosan (CS) and chitosan combined with the peptide GBMP1α (CS + GBMP1α), to improve bone growth. OsseoGuard® membranes, derived from bovine Achilles tendon type I collagen crosslinked with formaldehyde, were modified using CS and CS + GBMP1α. The functionalization, carried out with 1-ethyl-3-(3 dimethylaminopropyl)carbodiimide and sulfo-N-Hydroxysuccinimide (EDC/sulfo-NHS), was assessed through FT-IR and XPS analyses. Biological assays were performed by directly seeding human osteoblasts onto the materials to assess cell proliferation, mineralization, gene expression of Secreted Phosphoprotein 1 (SPP1) and Runt-Related Transcription Factor 2 (Runx2), and antibacterial properties. Both CS and CS + GBMP1α functionalizations significantly enhanced human osteoblast proliferation, mineralization, gene expression, and antibacterial activity compared to commercial membranes. The CS + GBMP1α functionalization exhibited superior outcomes in all biological assays. Mechanical tests showed no significant alterations of membrane biomechanical properties post-functionalization. The engineered membranes, especially those functionalized with CS + GBMP1α, are suitable for GBR applications thanks to their ability to enhance osteoblast activity and promote bone tissue regeneration. These findings suggest a potential advancement in the treatment of oral cavity problems requiring bone regeneration.

Definition of the Change Regulations in the Porosity of Semi-permeable Membranes After the Separation of Dairy Raw Materials

Topicality. The article provides a methodology for calculating structural and physical characteristics of semi-permeable membranes after their use in the technological process. During the operation of the membranes, the permeability decreases due to the clogging of their pores with colloidal substances. As a result, it is necessary to obtain data on the distribution of pores on the surface of the investigated ultrafiltration membrane. The aim of the article is to determine the change regularities in the porosity of the semi-permeable membrane, which is used in the technological process of separating dairy raw materials. This will make it possible to predict hydrodynamic properties of the ultrafiltration membrane. Research methods. A strain-measuring (statistical) method is offered, as well as structural and physical characteristics of semi-permeable membranes are determined in the process of membrane filtration of skimmed dairy raw materials. The possibility of constructing mathematical dependencies and methods for determining physical properties and structural analysis of the semi-permeable membrane is highlighted. This technique makes it possible to define not only the surface of the semi-permeable membrane, but also the surface of the polarisation layer of high molecular weight substances. Results. Based on the research results, the dependences of physical properties and structural components of the semi-permeable membrane after the processing of dairy raw materials are constructed. The results of the conducted study show that after ultrafiltration of skimmed dairy raw materials, the pore sizes undergo significant changes. Conclusions and discussion. An increase in the number of pores with a diameter of less than 10 nm is established. The spectrum of the radii of microcapillaries shifts towards decreasing, which occurs as a result of the deposition of particles of the dispersed phase in the microcapillaries. The implementation of research results can take place in industrial conditions, in order to determine the structural and physical characteristics of different types of membranes during the concentration of liquids of different origins for the development of new modifications of filter elements. The conditions for the industrial use of the obtained results are the resolution of issues relating to the laboratory studies of structural and physical characteristics with production results.

Engineering a microparticle-loaded rough membrane for guided bone regeneration modulating osteoblast response without inducing inflammation

Guided bone regeneration (GBR) is a widely used procedure that prevents the fast in-growth of soft tissues into bone defect. Among the different types of membranes, the use of collagen membranes is the gold standard. However, these membranes are implanted in tissue location where a severe acute inflammation will occur and can be negatively affected. The aim of this study was to develop a collagen-based membrane for GBR that incorporated alginate-hydroxyapatite microparticles. Membranes were manufactured using collagen type I and gelatin and alginate-hydroxyapatite microparticles. Membranes were assessed in terms of topography by scanning electron microscopy and confocal microscopy; stability by swelling after an overnight incubation in saline and enzymatic degradation against collagenase and mechanical properties by tensile tests. Furthermore, the biological response was assessed with SaOs-2 cells and THP-1 macrophages to determine alkaline phosphatase activity and inflammatory cytokine release. Our results showed that the incorporation of different percentages of these microparticles could induce changes in the surface topography. When the biological response was analyzed, either membranes were not cytotoxic to THP-1 macrophages or to SaOs-2 cells and they did not induce the release of pro-inflammatory cytokines. However, the different surface topographies did not induce changes in the macrophage morphology and the release of pro- and anti-inflammatory cytokines, suggesting that the effect of surface roughness on macrophage behavior could be dependent on other factors such as substrate stiffness and composition. Collagen-gelatin membranes with embedded alginate-hydroxyapatite microparticles increased ALP activity, suggesting a positive effect of them on bone regeneration, remaining unaffected the release of pro- and anti-inflammatory cytokines.

Removal of multiple pesticides from water by different types of membranes

Pesticides are used in agriculture to protect crops from pathogens, insects, fungi and weeds, but the release of pesticides into surface/groundwater by agriculture runoff and rain has raised serious concerns not only for the environment but also for human health. This study aimed to investigate the impact of surface properties on the performance of seven distinct membrane types utilized in nanofiltration (NF), reverse osmosis (RO) and forward osmosis (FO) processes in eliminating multiple pesticides from spiked water. Out of the membranes tested, two are self-fabricated RO membranes while the rest are commercially available membranes. Our results revealed that the self-fabricated RO membranes performed better than other commercial membranes (e.g., SW30XLE, NF270, Duracid and FO) in rejecting the targeted pesticides by achieving at least 99% rejections regardless of the size of pesticides and their log Kow value. Despite the marginally lower water flux exhibited by the self-fabricated membrane compared to the commercial BW30 membrane, its exceptional ability to reject both mono- and divalent salts renders it more apt for treating water sources containing not only pesticides but also various dissolved ions. The enhanced performance of the self-fabricated RO membrane is mainly attributed to the presence of a hydrophilic interlayer (between the polyamide layer and substrate) and the incorporation of hydrophilic nanosheets in tuning its surface characteristics. The findings of the work provide insight into the importance of membrane surface modification for the application of not only the desalination process but also for the removal of contaminants of emerging concern.

Polyvinyl alcohol: Starch based membrane scaffolds for tissue transparency requirements: Fabrication, characterization and cytotoxicity studies

In this study, the characterization and cytocompatibility of polyvinyl alcohol:starch (PVA:ST) based membrane tissue scaffolds developed for tissue transparency requirements in tissue engineering applications were evaluated in the presence of sodium dodecyl sulphate (SDS). In this context, two different amounts of SDS were added to the polymer structure of transparent membrane scaffolds to roughen the surfaces of PVA:ST membranes and to promote cell adhesion. In the light of this aim, three different types of membranes were created: A constant PVA:ST ratio of 9:1 (wt:wt) was used as a control and varying amounts of SDS (2 and 4 wt% of the total polymer amount) were added to the polymer solutions. Membrane tissue scaffolds were formed by freeze-drying method. Scaffold properties such as morphology, transparency, water absorption, chemical structure and cytocompatibility were investigated. In terms of physicochemical properties, it was observed that with the addition of SDS, the membranes had a rougher surface while retaining water retention and transparency. In cytotoxicity studies, the membranes were found to be non-cytotoxic and promoted cell proliferation as assessed by MTT assay. Furthermore, the PVA:ST membrane scaffold with 4% SDS added was able to promote the attachment, migration and proliferation of Mouse Embryonic Fibroblasts (MEFs) more than the control group. Overall, the results indicate that SDS-added PVA:ST scaffold membranes are suitable for human corneal stromal regeneration, wound dressing material and neural tissue engineering applications.

MFI Zeolite Membranes and PV Separation of Isopropanol-Water Azeotropic Mixtures

Membrane separation process has become one of the emerging technologies that undergo a rapid growth since few decades. Pervaporation (PV) is one among the membrane separation processes which gained foremost interest in the chemical and allied industries. It is an effective and energy-efficient technology that carries out separations, which are difficult to achieve by conventional separation processes. Inorganic membranes such as zeolite membranes with uniform, molecular-sized pores, selective adsorption and molecular sieving action offer unique type of pervaporation membrane for a number of separation processes. This paper presents the role of MFI-zeolite membrane and its progress in the pervaporation process. The fundamental aspects of pervaporation over different types of membranes are reviewed and compared. The focus of this paper is on zeolite membrane synthesis, membrane characterization and pervaporation studies. The transport mechanism during pervaporation is discussed and the issues related with pervaporation are addressed. Innovation and future development of zeolite membrane in pervaporation are also presented.

Deodorisation of Ventilated Air from a Fat-Processing Plant Using Different Types of Biofilter Fillings and Membranes

The aim of the research is to assess changes in odour concentration in the ventilated air of a production hall, using different types of biofilter fillings and different types of membranes. Deodorisation was carried out using a mobile combined biofilter at a plant producing lard and liquid oils. Ventilated air from the hall contained organic and inorganic pollutants. Two types of fillings were used for technological tests: stumpwood chips mixed with pine bark and a mix of stumpwood chips with pine bark and green waste compost. Two types of membranes were also used, differing in thickness, permeability, and water resistance. The subjects of the research were the air supplied to the filter, lifted directly from the bed, and the air above the membranes. The deodorisation efficiency—the percentage reduction in the odour concentration value as a result of air flow through the bed and membranes—was calculated. The filtration methods used allowed the selection of the most advantageous technological variant from the point of view of deodorisation effectiveness: a mix of stumpwood chips with pine bark and the Pro Eko Tex UV membrane. It has a total odour reduction efficiency of 99.3–99.9% and has been added to full-scale implementation works.

Guided Tissue and Bone Regeneration Membranes: A Review of Biomaterials and Techniques for Periodontal Treatments.

This comprehensive review provides an in-depth analysis of the use of biomaterials in the processes of guided tissue and bone regeneration, and their indispensable role in dental therapeutic interventions. These interventions serve the critical function of restoring both structural integrity and functionality to the dentition that has been lost or damaged. The basis for this review is laid through the exploration of various relevant scientific databases such as Scopus, PubMed, Web of science and MEDLINE. From a meticulous selection, relevant literature was chosen. This review commences by examining the different types of membranes used in guided bone regeneration procedures and the spectrum of biomaterials employed in these operations. It then explores the manufacturing technologies for the scaffold, delving into their significant impact on tissue and bone regenerations. At the core of this review is the method of guided bone regeneration, which is a crucial technique for counteracting bone loss induced by tooth extraction or periodontal disease. The discussion advances by underscoring the latest innovations and strategies in the field of tissue regeneration. One key observation is the critical role that membranes play in guided reconstruction; they serve as a barrier, preventing the entry of non-ossifying cells, thereby promoting the successful growth and regeneration of bone and tissue. By reviewing the existing literature on biomaterials, membranes, and scaffold manufacturing technologies, this paper illustrates the vast potential for innovation and growth within the field of dental therapeutic interventions, particularly in guided tissue and bone regeneration.

The Complex Proteolipidic Behavior of the SARS-CoV-2 Envelope Protein Channel: Weak Selectivity and Heterogeneous Oligomerization.

The envelope (E) protein is a small polypeptide that can form ion channels in coronaviruses. In SARS coronavirus 2 (SARS-CoV-2), the agent that caused the recent COVID-19 pandemic, and its predecessor SARS-CoV-1, E protein is found in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC), where virion budding takes place. Several reports claim that E protein promotes the formation of "cation-selective channels". However, whether this term represents specificity to certain ions (e.g., potassium or calcium) or the partial or total exclusion of anions is debatable. Herein, we discuss this claim based on the available data for SARS-CoV-1 and -2 E and on new experiments performed using the untagged full-length E protein from SARS-CoV-2 in planar lipid membranes of different types, including those that closely mimic the ERGIC membrane composition. We provide evidence that the selectivity of the E-induced channels is very mild and depends strongly on lipid environment. Thus, despite past and recent claims, we found no indication that the E protein forms cation-selective channels that prevent anion transport, and even less that E protein forms bona fide specific calcium channels. In fact, the E channel maintains its multi-ionic non-specific neutral character even in concentrated solutions of Ca2+ ions. Also, in contrast to previous studies, we found no evidence that SARS-CoV-2 E channel activation requires a particular voltage, high calcium concentrations or low pH, in agreement with available data from SARS-CoV-1 E. In addition, sedimentation velocity experiments suggest that the E channel population is mostly pentameric, but very dynamic and probably heterogeneous, consistent with the broad distribution of conductance values typically found in electrophysiological experiments. The latter has been explained by the presence of proteolipidic channel structures.

The Effect of Different Types of Collagen Membranes on Peri-Implant Dehiscence Defects.

This experimental study aimed to compare the bone-implant contact (BIC) following guided bone regeneration with 3 bioabsorbable collagen membranes on peri-implant dehiscence defects. Forty-eight standard dehiscence defects were created in the sheep iliac bone crest, and dental implants were placed into the defects. With the guided bone regeneration technique, the autogenous graft was placed into the defect and covered with different types of membranes: Geistlich Bio-Gide, Ossix Plus, and Symbios Prehydrated were covered. One group was left without a membrane as the control group (C) by applying only an autogenous graft. After recovery periods of 3 and 6 weeks, the experimental animals were sacrificed. Histologic sections were prepared by a nondecalcified method, and BIC was examined. There was no statistically important difference between groups in the third week ( P >0.05). A statistically significant difference between groups was found in the sixth week ( P <0.01). Bone-implant contact values of the C group were significantly lower than those of the Geistlich Bio-Gide and Ossix Plus groups ( P <0.05). There was no statistically significant difference between control and Symbios Prehydrated groups ( P >0.05). In all sections, osseointegration was observed, with no signs of inflammation, necrosis, or foreign body reaction. In our study, it has been concluded that the resorbable collagen membranes used in treating peri-implant dehiscence defects might affect the BIC, and the success varies according to the type of membrane used.

Advancements in the development of membranes employed in microbial electrochemical technologies

Energy generation by the use of microbes is being widely studied for meeting the demands of ever-growing global energy consumption. In this veneration, microbial electrochemical technologies (METs) are one such technology, which is used to produce energy simultaneously along with wastewater treatment through the microbial degradation of organic matter. Further, the membranes employed in different types of METs play a crucial role in their operation and efficacy, and also their economic feasibility critically affects the scalability of METs. Therefore, the present review, elucidates the different types of membranes used in both lab-scale and field-scale METs, the performance of the METs in terms of wastewater treatment, coulombic efficiency and energy production with different membranes. Further, recent development in the field of membranes and their application in various types of METs and status quo are included along with proposing the future directions in membrane-based research.

Guided Tissue Regeneration in Class IV External Cervical Resorption: A Case Report

External cervical resorption (ECR) is a type of dental resorption that originates from the loss of the cementum's protective layer. The direct exposure of dentin to the periodontal ligament may lead to the invasion of clastic cells through an entry point on the external root surface into the dentinal tissue, causing resorption. Depending on the extension of ECR, different treatments are proposed. Although the literature presents distinct materials and methods for restoring ECR areas, an existing gap is related to care in the treatment of the supporting periodontal tissue. Guided tissue regeneration (GTR)/guided bone regeneration includes the stimulation of bone formation in bone defects using different types of membranes (resorbable and nonresorbable), regardless of its association with bone substitutes or grafts. Despite the benefits of guided bone regeneration, the application of this method in cases of ECR is still under-explored in the literature. Thus, the present case report uses GTR with xenogenic material and polydioxanone membrane in a case of class IV ECR. The success of the present case is related to the correct diagnosis and treatment plan. Complete debridement of resorption areas and restoration with biodentine were effective in tooth repair. GTR contributed to the stabilization of supporting periodontal tissues. The association of the xenogeneic bone graft with the polydioxanone membrane proved to be a viable option for restoring the health of the periodontium.

Anatomy of the fetal membranes: insights from spinning disk confocal microscopy

PurposeThe fetal membranes are essential for the maintenance of pregnancy, and their integrity until parturition is critical for both fetal and maternal health. Preterm premature rupture of the membranes (pPROM) is known to be an indicator of preterm birth, but the underlying architectural and mechanical changes that lead to fetal membrane failure are not yet fully understood. The aim of this study was to gain new insights into the anatomy of the fetal membrane and to establish a tissue processing and staining protocol suitable for future prospective cohort studies.MethodsIn this proof of principle study, we collected fetal membranes from women undergoing vaginal delivery or cesarean section. Small membrane sections were then fixed, stained for nucleic acids, actin, and collagen using fluorescent probes, and subsequently imaged in three dimensions using a spinning disk confocal microscope.ResultsFour fetal membranes of different types were successfully processed and imaged after establishing a suitable protocol. Cellular and nuclear outlines are clearly visible in all cases, especially in the uppermost membrane layer. Focal membrane (micro) fractures could be identified in several samples.ConclusionThe presented method proves to be well suited to determine whether and how the occurrence of membrane (micro) fractures and cellular jamming correlate with the timing of membrane rupture and the mode of delivery. In future measurements, this method could be combined with mechanical probing techniques to compare optical and mechanical sample information.

Parametric finite element analysis of laminated coupling

AbstractTo systematically and efficiently study the relationship between the design parameters and the strength and performance of the laminated coupling, it is expected to provide a theoretical basis for the design and selection of the coupling. Based on ANSYS parametric design language, parametric modeling and analysis were carried out on four different types of membranes, namely circular, multilateral, joint and plum‐pattern membranes. The loads and constraints were parameterized and the automatic grid division and analytical parameter control were realized, so as to obtain the stress distribution rule of the membranes. Based on Python language and parameterized commands, the secondary development of the membrane parametric finite element analysis tool was provided. The influence law of the factors such as angular displacement, torque, thickness, and the number of holes on the membrane performance was studied respectively, so as to achieve efficient finite element analysis. Results show that stress concentration exists near the hole edge of the membranes under the action of torque and angular displacement. Both the increase of torque and angular displacement will maximize the equivalent stress of the membranes, and appropriately reducing the thickness of the single membrane can lower the equivalent stress of the membranes.

Pilot scale nanofiltration membrane fabrication containing ionic co-monomers and halloysite nanotubes for textile dye filtration.

Wastewater from the textile industry contains high concentrations of pollutants, so the wastewater must be treated before it is discharged. In addition, the reuse of treated wastewater should be considered from an environmental point of view, as large volumes of wastewater are produced. Since textile wastewater mainly contains dyestuffs, it must be treated effectively using environmentally friendly technologies. Membrane processes are widely used in textile wastewater treatment as they have distinct advantages over conventional wastewater treatment methods. This study reports the pilot-scale manufacturing and characterization of three different NF membranes. Three different types of membranes were fabricated. The fabricated membranes were compared through characterization by surface properties, chemical structure and morphology. Membranes were tested for pure water flux. Then the synthetic wastewater (SWW) was tested for flux and rejection. Lastly, the textile wastewater was tested. The textile wastewater flux of pure piperazine (PIP), 60% S-DADPS and 0.04% halloysite nanotubes (HNTs) were 22.42, 79.58 and 40.06 L m-2 h-1. It has been proven that the 60% s-DADPS membrane provides up to four times improvement in wastewater flux and simultaneously. In addition, NF membranes produced using HNT and sDADPS on a pilot scale have brought innovation to the literature with the good results obtained.

Research progress and prospects on hydrogen separation membranes

Abstract Membrane separation technologies, with a broad application prospect in the field of hydrogen separation, are characterized by the simplicity of the devices, high energy efficiency and environmental friendliness. The performance of separation membranes is the primary factor that determines the efficiency of hydrogen separation. Therefore, the development of hydrogen separation membranes is always a research focus. This paper presents and reviews the research developments and features of organic membranes, inorganic membranes and hybrid matrix membranes for hydrogen separations. First, the characterization methods of key index parameters of membrane materials are presented. Second, the performance parameters of different types of membrane are compared. Finally, the trend of technological development of different types of membrane materials is forecast.

Tracking lipid-induced effects on membrane protein structure in real time.

Lipids in biological membranes can act as allosteric modulators of membrane protein function. P-type ATPase proteins carry out ATP-dependent transport of mostly ions across several different types of membranes. It has been shown that both general properties such as membrane thickness and interactions to lipids at specific protein sites dictate P-type ATPase activity. We have developed a methodology to track P-type ATPase domain rearrangements in real time triggered by laser-induced release of ATP and subsequent monitoring by synchrotron X-ray pulses. This time-resolved X-ray solution scattering (TR-XSS) technique was used to capture the dynamics of an equilibrium state of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA1a), and transient states at 1.5 and 13 milliseconds. The 13-millisecond state showed a previously unresolved actuator (A) domain arrangement that exposed the ADP-binding site after phosphorylation. To identify the effects of protein-lipid interactions, we have now used the TR-XSS technique to register kinetics and structural dynamics in a Ca2+-transporting P-type ATPase from Listeria monocytogenes (LMCA1) in nanodiscs at different lipid compositions. In negatively charged POPG lipids, the LMCA1 reaction kinetics and structural dynamics were reminiscent of the SERCA1a isoform, which is in agreement with the bacterial membranes being predominantly negatively charged. In uncharged POPC nanodiscs, the LMCA1 reaction was significantly different with slow buildup of the rate-limiting state. The results enable a mechanistic view of how protein-lipid interactions regulate the P-type ATPase reaction cycle. The TR-XSS technique presents a unique possibility to simultaneously determine kinetics and structural rearrangements in P-type ATPases to better understand the transport reactions and their regulation mechanisms.

Surface Engineering of a Bioartificial Membrane for Its Application in Bioengineering Devices.

Membrane technology is playing a crucial role in cutting-edge innovations in the biomedical field. One such innovation is the surface engineering of a membrane for enhanced longevity, efficient separation, and better throughput. Hence, surface engineering is widely used while developing membranes for its use in bioartificial organ development, separation processes, extracorporeal devices, etc. Chemical-based surface modifications are usually performed by functional group/biomolecule grafting, surface moiety modification, and altercation of hydrophilic and hydrophobic properties. Further, creation of micro/nanogrooves, pillars, channel networks, and other topologies is achieved to modify physio-mechanical processes. These surface modifications facilitate improved cellular attachment, directional migration, and communication among the neighboring cells and enhanced diffusional transport of nutrients, gases, and waste across the membrane. These modifications, apart from improving functional efficiency, also help in overcoming fouling issues, biofilm formation, and infection incidences. Multiple strategies are adopted, like lysozyme enzymatic action, topographical modifications, nanomaterial coating, and antibiotic/antibacterial agent doping in the membrane to counter the challenges of biofilm formation, fouling challenges, and microbial invasion. Therefore, in the current review, we have comprehensibly discussed different types of membranes, their fabrication and surface modifications, antifouling/antibacterial strategies, and their applications in bioengineering. Thus, this review would benefit bioengineers and membrane scientists who aim to improve membranes for applications in tissue engineering, bioseparation, extra corporeal membrane devices, wound healing, and others.

Decarbonization of Power and Industrial Sectors: The Role of Membrane Processes.

Carbon dioxide (CO2) is the single largest contributor to climate change due to its increased emissions since global industrialization began. Carbon Capture, Storage, and Utilization (CCSU) is regarded as a promising strategy to mitigate climate change, reducing the atmospheric concentration of CO2 from power and industrial activities. Post-combustion carbon capture (PCC) is necessary to implement CCSU into existing facilities without changing the combustion block. In this study, the recent research on various PCC technologies is discussed, along with the membrane technology for PCC, emphasizing the different types of membranes and their gas separation performances. Additionally, an overall comparison of membrane separation technology with respect to other PCC methods is implemented based on six different key parameters-CO2 purity and recovery, technological maturity, scalability, environmental concerns, and capital and operational expenditures. In general, membrane separation is found to be the most competitive technique in conventional absorption as long as the highly-performed membrane materials and the technology itself reach the full commercialization stage. Recent updates on the main characteristics of different flue gas streams and the Technology Readiness Levels (TRL) of each PCC technology are also provided with a brief discussion of their latest progresses.

A novel method for Ion Exchange Capacity characterization applied to Anion Exchange Membranes for Water Electrolysers

Hydrogen production from water electrolysis, hydrogen fuel cells and redox flow batteries are the right approach for the renewable energy sector because the electricity generated by solar, wind, photovoltaic, hydroelectric can be managed with a carbon-free approach. These technologies all have in common one fundamental component: the membrane. Different types of membranes have been developed for both cationic and anionic exchange, and recently, research activity focalized on improving their performances is very fervent. One fundamental characteristic of a membrane is its Ion Exchange Capacity (IEC), i.e. the density of charged functionalizing groups. Within our research project NEMESI, funded by EU-PNRR (ID: RSH2B_000002), and dedicated to Anion Exchange Membrane Water Electrolysis, we studied and validated a novel alternative method to measure IEC. The present titration methods have limitations for the need of dedicated hardware or qualitative inspection of their color-turning endpoint. The proposed method, based on the redox titration of potassium ferricyanide with ascorbic acid, allows a quantitative and independent assessment based on both potentiometric and spectrophotometric measurements, along with the usually adopted visual observation, as the yellow-colored ferricyanide is reduced to colorless ferrocyanide. Moreover, if compared to the classical Mohr titration with silver nitrate, the new method can be carried out at variable ferricyanide concentrations during the addition of the ascorbic acid, so a complete curve of the redox reaction can be constructed: the initial ferricyanide ion load of the membrane (IEC) can thus be derived in a more precise way than with a single-point evaluation. Only one Ag/AgCl reference electrode and a platinum working electrode are required without any power supply/potentiostat. The proposed method was validated using Anion Exchange Membranes with known IEC.