Selective Membrane Research Articles

Interface dynamics in electroosmotic flow systems with non-Newtonian fluid frontiers

Abstract Microfluidic applications involving liquid manipulation, selective membranes, and energy harvesting strongly em-phasize the importance of the electrokinetic phenomenon, which is widely used at multiple fluid and electrochemi-cal interfaces. However, critical scientific issues that address multifield coupling and multiscale physics have not been well addressed in non-Newtonian fluids. In this paper, electrical field–fluid flow–ion transport coupling is numerically implemented in two mainstream problems, i.e., induced electroconvection phenomena at ion-selective interfaces and induced charge electroosmosis in polarized cylinders. The effects of different non-Newtonian rheo-logical properties, which are absent in Newtonian fluids, on the interfacial dynamics, instability and ion transport are examined. The results reveal that the non-Newtonian rheology significantly modulates the statistical data and interfacial phenomena. Generalized power-law fluids alter velocity and interfacial charge profiles, with shear thin-ning enhancing ion transport to lower overlimiting current thresholds and shear thickening broadening the limiting current region (with hindered ion transport). In Boger-type Oldroyd-B fluids, the addition of polymer decreases the velocity amplitude and increases the interface resistance. At low voltages, polymer viscoelasticity minimally affects the ohmic and limiting regions, but under convection-dominated flow, different rheological parameters, such as the viscosity ratio, Weissenberg number, anisotropic parameter, and electrohydrodynamic coupling con-stants, enable controllable regulation of ion transport behavior across a wide range. Finally, this paper states that modulated electroosmosis by complex charged polymers is the future cutting edge. The relevant results supple-ment the non-Newtonian physics of electrokinetic systems and provide guidance for the design and operation of microfluidic devices.

Enhancing the Separation Performance of Chitosan Membranes Through the Blending with Deep Eutectic Solvents for the Pervaporation of Polar/Non-Polar Organic Mixtures

This study explores the development of chitosan-based membranes blended with three distinct deep eutectic solvents (DESs) for the pervaporation separation of methanol and methyl tert-butyl ether. DESs were selected for their eco-friendly properties and their potential to enhance membrane performance. The chitosan (CS) membranes, both crosslinked and non-crosslinked, were characterized in terms of morphology, chemical composition, wettability, mechanical resistance, and solvent uptake. Pervaporation tests revealed that incorporating DESs significantly enhanced the membranes’ selective permeability toward methanol, with up to a threefold increase in separation efficiency compared to pristine CS membranes. The membranes demonstrated a strong dependence on feed temperature, with higher temperatures improving permeation flux but reducing separation factor. Crosslinking with glutaraldehyde further increased membrane selectivity by reducing free volume into the polymer matrix. These findings underscore the potential of DESs as green additives for improving the performance of biopolymer membranes, making them promising candidates for efficient and eco-friendly organic–organic separations.

Enrichment of lithium ions for battery application by electrolysis through a nanoporous membrane

In recent years, lithium (Li) has become a valuable commodity widely used in rechargeable batteries. The present study aims to extract battery-grade lithium-ion, as lithium hydroxide (LiOH), from lithium chloride (LiCl) solution by the membrane electrolysis process. Experiments are performed using a commercial cation exchange membrane and an indigenous High flux-Nanofiltration 300 alkali resistant (HF-NF 300 AR) nanoporous membrane. The dual-chamber electrolytic cell incorporates a selective membrane to separate the feed and concentrate chambers containing LiCl solution and deionized water. These two chambers are connected with titanium electrodes through the external circuit. The in-situ design of the compact two-chambered acrylic electrolytic cell helps to separate metal ions from ionizable salts of sodium, lithium, magnesium, potassium, etc. The experiment is conducted on a laboratory scale by varying the LiCl concentration at voltages of 24 V and 36 V. The feed and concentrate solutions are analyzed for pH, conductivity, and total dissolved solids. Inductively coupled plasma-optical emission spectrometry evaluates the presence of metal ions in the solution. The study shows effective metal ion recovery and separation to achieve battery-grade Li.

Photoswitchable Detergents for Light-Controlled Liposome Lysis and Channel Gating.

Modulation of membrane properties via photoswitchable lipids has attracted attention due to the unparalleled spatiotemporal resolution of their functional control. Beside lipids, detergents are another prominent class for selective membrane perturbations owing to their ease of handling and spontaneous insertion in lipid bilayers. Herein, we describe the synthesis and characterization of three classes of visible light-sensitive surfactants with various azobenzene tail chain lengths. The photoswitchable detergents show water-solubility and micellization as well as undergo reversible isomerization under blue-/green light illumination. We demonstrate that the light-induced structural change of azobenzene can lead to vesicle rupture, making them a tool for controlled cargo release from vehicles. Via spontaneous insertion into the plasma membrane of mammalian cells transiently transfected with MscL, we used the azobenzene-derived detergents to optically activate the transmembrane mechanosensitive channel. This led to the rapid controlled uptake of membrane-impermeable molecules. Since detergents are extensively used in biochemistry and biotechnology, we propose that the photoswitchable detergents will be useful tools for the spatiotemporal modulation of membrane properties. Additionally, our work provides a design strategy for new detergents in membrane (protein) research.

Toward Carbon‐Negative Methanol Production from Biogas: Intensified Membrane Reactor

AbstractThe modern world's major challenges, such as global warming, air pollution, and increasing energy demands, escalate the importance of sustainable development and transition toward renewables using innovative and environmentally friendly solutions, such as intensifying chemical processes, to reduce carbon footprints effectively. Aiming to enhance the process toward negative carbon emissions, this perspective explores the intensified membrane reactors for reducing the energy intensity of converting biogas into methanol, a versatile chemical feedstock, and renewable liquid fuel. Syngas and methanol synthesis processes, catalysts, and membranes were explored, and novel reactor designs were proposed. Introduction of selective membranes into the catalytic reaction zone to combine synthesis separation steps could enhance the system efficiency and intensify the process by recycling energy and materials, besides reducing costs and required energy for the separation process: the continuous harnessing of products shifts reactions toward desired species while recycling energy and materials enhances the process efficiency, and separating water from methanol reduces the required energy and costs of extra processes for methanol separation. The successful implementation of this technology holds significant promise for sustainable developments in producing chemicals and renewable fuel from renewable biogas and reducing methane and carbon dioxide emissions toward achieving carbon‐negative technologies.

Enhancing CO2/N2 and CO2/CH4 Separation Properties of PES/SAPO-34 Membranes Using Choline Chloride-Based Deep Eutectic Solvents as Additives

CO2 separation is an important environmental method mainly used in reducing CO2 emissions to mitigate anthropogenic climate change. The use of mixed-matrix membranes (MMMs) arrives as a possible answer, combining the high selectivity of inorganic membranes with high permeability of organic membranes. However, the combination of these materials is challenging due to their opposing nature, leading to poor interactions between polymeric matrix and inorganic fillers. Many additives have been tested to reduce interfacial voids, some of which showed potential in dealing with compatibility problems, but most of them lack further studies and optimization. Deep eutectic solvents (DESs) have emerged as IL substitutes since they are cheaper and environmentally friendly. Choline chloride-based deep eutectic solvents were studied as additives in polyethersulfone (PES)/SAPO-34 membranes to improve CO2 permeability and CO2/N2 and CO2/CH4 selectivity. SAPO-34 crystals of 150 nm with a high surface area and microporosity were synthesized using dry-gel methodology. The PES/SAPO-34 membranes were optimized following previous work and used in a defined composition, using 5 or 10 w/w% of DES during membrane preparation. All MMMs were characterized by their ideal gas permeability using N2 and CO2 pure gasses. Selected membranes were also tested using CH4 pure gas. The results presented that 5 w/w%, in polymer mass, of ChCl–glycerol presented the best result over the synthesized membranes. An increase of 200% in CO2 permeability maintains the CO2/N2 selectivity for the non-modified PES/SAPO-34 membrane. A CO2/CH4 selectivity of 89.7 was obtained in PES/SAPO-34/ChCl-glycerol membranes containing 5 w/w% of this DES, which is an outstanding ideal separation performance for MMMs when compared to other results in the literature. FTIR analysis reiterates the presence of glycerol in the membranes prepared. Dynamic Mechanical Thermal Analysis (DMTA) shows that the addition of 5 w/w% of DES does not impact the membrane flexibility or polymer structure. However, in concentrations higher than 10 w/w%, the inclusion of DES could lead to high membrane rigidification without impacting the overall thermal resistance. SEM analysis of DES-enhanced membranes presented asymmetric final membranes and reaffirmed the results obtained in DMTA about rigidified structures and lower zeolite–polymer interaction with higher concentrations of DES.

Research Progress in Enhancing Proton Conductivity of Sulfonated Aromatic Polymers with ZIFs for Fuel Cell Applications

The escalating global temperatures and their adverse effects underscore the growing imperative for the widespread adoption of clean fuels, notably hydrogen. Proton Exchange Membrane Fuel Cells (PEMFC) emerge as a pivotal green energy technology, facilitating electricity and water generation. The optimization of PEMFC efficiency hinges on the judicious selection and fabrication of polymer membranes. Within innovative materials, Zeolitic Imidazolate Frameworks (ZIFs) represent a novel subclass within the expansive family of Metal-Organic Frameworks (MOFs). ZIFs exhibit promising potential in PEMFCs, owing to their distinctive properties such as a substantial contact surface, inherent porosity, and a sizable pore volume. This comprehensive review delves into composite membranes featuring ZIFs, shedding light on their chemical and thermal attributes. Additionally, the exploration extends to elucidating the diverse applications of ZIF compounds, accompanied by an in-depth discussion of selected chemical and thermal properties inherent to ZIF compounds. Incorporating ZIFs into various polymers yielded intriguing outcomes, demonstrating a notable enhancement in proton conductivity. The compilation of this review aims to provide researchers with foundational insights into the realm of ZIFs, serving as a valuable resource for future investigations and advancements in the field.

Performance of Single Nanopore and Multi-Pore Membranes for Blue Energy.

The salinity gradient power extracted from the mixing of electrolyte solutions at different concentrations through selective nanoporous membranes is a promising route to renewable energy. However, several challenges need to be addressed to make this technology profitable, one of the most relevant being the increase of the extractable power per membrane area. Here, the performance of asymmetric conical and bullet-shaped nanopores in a 50 nm thick membrane are studied via electrohydrodynamic simulations, varying the pore radius, curvature, and surface charge. The output power reaches ~60 pW per pore for positively charged membranes (surface charge σw=160 mC/m2) and ~30 pW for negatively charges ones, σw=-160 mC/m2 and it is robust to minor variations of nanopore shape and radius. A theoretical argument that takes into account the interaction among neighbour pores allows to extrapolate the single-pore performance to multi-pore membranes showing that power densities from tens to hundreds of W/m2 can be reached by proper tuning of the nanopore number density and the boundary layer thickness. Our model for scaling single-pore performance to multi-pore membrane can be applied also to experimental data providing a simple tool to effectively compare different nanopore membranes in blue energy applications.

Design of Self-Standing Chiral Covalent-Organic Framework Nanochannel Membrane for Enantioselective Sensing.

Nanochannel membranes are promising materials for enantioselective sensing. However, it is difficult to make a compromise between the selectivity and permeability in traditional nanochannel membranes. Therefore, new types of nanochannel membranes with high enantioselectivity and excellent permeability should be explored for chiral analysis. Here, asymmetric catalysis strategy is reported for interfacial polymerization synthesis of chiral covalent-organic framework (cCOF) nanochannel membrane for enantioselective sensing. Chiral phenylethylamine (S/R-PEA) and 2,4,6-triformylphloroglucinol (TP) are used to prepare chiral TP monomer. 4,4',4″-triaminotriphenylamine (TAPA) is then condensed with chiral TP to obtain cCOF nanochannel membrane via a C═N Schiff-base reaction. The molar ratio of TP to S/R-PEA is adjusted so that S/R-PEA is bound to the aldehyde only or both the aldehyde and hydroxyl groups on TP to obtain chiral-induced COF (cCOF-1) or both chiral-induced and modified COF (cCOF-2) nanochannel membrane, respectively. The prepared cCOF-2 nanochannel membrane showed two times more selectivity for limonene enantiomers than cCOF-1 nanochannel membrane. Furthermore, cCOF-2 nanochannel platform exhibited excellent sensing performance for other chiral molecules such as limonene, propanediol, methylbutyric acid, ibuprofen, and naproxen (limits of detection of 19-42ngL-1, enantiomer excess of 63.6-86.3%). This work provides a promising way to develop cCOF-based nanochannel enantioselective sensor.

Evaluating membranes for hydrogen storage and utilization in next-generation aviation systems

This study aims to provide a comprehensive evaluation of membrane technologies for hydrogen-related processes in aviation, specifically focusing on hydrogen production, hydrogen separation, and fuel cells. As aviation seeks to transition to cleaner energy solutions, the selection of appropriate membranes is critical for ensuring efficiency and sustainability. The research utilizes the Analytic Hierarchy Process (AHP) to systematically assess membrane alternatives based on key criteria: economic factors, environmental impact, technical performance, and technological maturity. By conducting pairwise comparisons and detailed matrix calculations, this study establishes the relative importance of sub-criteria and ranks membrane types for each hydrogen-related application. The analysis identifies Nonporous Dense Films as the most effective membrane for hydrogen production, due to their balance of cost and technical performance. For hydrogen separation, Ceramic and Metal Membranes are determined to be the optimal choice, offering superior durability, hydrogen permeability, and thermal stability. In fuel cell applications, Electrically Charged Membranes are found to be the most suitable for Proton Exchange Membrane Fuel Cells (PEMFCs), while Ceramic and Metal Membranes excel in Solid Oxide Fuel Cells (SOFCs). The outcomes of this study not only highlight the most suitable membranes for different aviation hydrogen processes but also offer a strategic framework for decision-makers. By identifying the key factors driving membrane selection, this research contributes to advancing hydrogen adoption in aviation, facilitating the development of efficient, low-emission technologies for the future of sustainable air travel.

Toward circular greenhouse wastewater reuse: advancements in cation exchange membranes for selective Na+/K+ separation using electrodialysis systems

ABSTRACT Driven by the growing need for alternative water sources and forthcoming stringent nutrient discharge regulations, there is growing interest in developing selective membrane solutions to facilitate circular greenhouse wastewater reuse (as emphasized in the European Union's Horizon 2020 ULTIMATE project). For electrodialysis systems, sodium (Na+) over potassium (K+) selective membranes are essential to achieve minimal liquid discharge. This study addresses the challenge of developing selective, efficient, and scalable Na+/K+ cation exchange membranes. State-of-the-art cation exchange membrane developments were reviewed and the functionalization of commercial membranes with crown ethers was identified as a promising approach. Two crown ether–modified membranes (15-crown-5 (15C5) and 18-crown-6 (18C6)) were developed, characterized, and tested in equimolar and greenhouse wastewater binary feed ratios. While the results demonstrated low overall selectivity, the 15C5-modified membrane showed a marginal enhancement in K+ selectivity, suggesting the need for further optimization. The study concludes with recommendations for the future development of Na+/K+ selective membranes, highlighting the potential of machine learning approaches to expedite progress. This research provides a foundational step toward practical and scalable Na+/K+ ion separation solutions, for achieving minimal liquid discharge in greenhouse horticulture.

Membrane Fusion Mediated by Cationic Helical Peptide L-MMBen through Phosphatidylglycerol Recruitment.

Membrane fusion is the basis for many biological processes, which holds promise in biomedical applications including the creation of engineered hybrid cells and cell membrane functionalization. Extensive research efforts, including investigations into DNA zippers and carbon nanotubes, have been dedicated to the development of membrane fusion strategies inspired by natural SNARE proteins; nevertheless, achieving a delicate balance between membrane selectivity and high fusion efficiency through precise molecular engineering remains unclear. In our recent study, we successfully designed L-MMBen, a cationic helical antimicrobial peptide that exhibits remarkable antimicrobial efficacy while demonstrating moderate cytotoxicity. In this work, we demonstrate the effective and selective induction of fusion between phosphatidylglycerol (PG)-containing membranes by L-MMBen. By combining biophysical assays at the single-vesicle level with computer simulations at the molecular level, we discovered that L-MMBen can stably adsorb onto the surface of PG-containing membranes, leading to the formation of stalk structures between vesicles and ultimately resulting in membrane fusion. Furthermore, the occurrence of fusion is attributed to the unique ability of L-MMBen to recruit PG lipids and bridge adjacent vesicles. In contrast, its nonhelical counterpart DL-MMBen was found to lack this capability despite possessing an identical positive charge. These findings present an alternative molecule for achieving selective membrane fusion and provide insights for designing helical peptides with diverse applications.

Advancements in Mixed-Matrix Membranes for Various Separation Applications: State of the Art and Future Prospects

Integrating nanomaterials into membranes has revolutionized selective transport processes, offering enhanced properties and functionalities. Mixed-matrix membranes (MMMs) are nanocomposite membranes (NCMs) that incorporate inorganic nanoparticles (NPs) into organic polymeric matrices, augmenting mechanical strength, thermal stability, separation performance, and antifouling characteristics. Various synthesis methods, like phase inversion, layer-by-layer assembly, electrospinning, and surface modification, enable the production of tailored MMMs. A trade-off exists between selectivity and flux in pristine polymer membranes or plain inorganic ceramic/zeolite membranes. In contrast, in MMMs, NPs exert a profound influence on membrane performance, enhancing both permeability and selectivity simultaneously, besides exhibiting profound antibacterial efficacy. Membranes reported in this work find application in diverse separation processes, notably in niche membrane-based applications, by addressing challenges such as membrane fouling and degradation, low flux, and selectivity, besides poor rejection properties. This review comprehensively surveys recent advances in nanoparticle-integrated polymeric membranes across various fields of water purification, heavy metal removal, dye degradation, gaseous separation, pervaporation (PV), fuel cells (FC), and desalination. Efforts have been made to underscore the role of nanomaterials in advancing environmental remediation efforts and addressing drinking water quality concerns through interesting case studies reported in the literature.

Polyamide membranes with tannic acid-ZIF-8 for highly permeable and selective ion-ion separation

Highly permeable polyamide (PA) membranes with precise ion selection can be used for many energy-efficient chemical separations but are limited by membrane inefficiencies. Herein, polyphenol-mediated ZIF-8 nanoparticles with hydroxyl-rich hollow structure were synthesized by tannic acid tailored regulation. PA-based membranes with fast penetration, high retention, and precise Cl−/SO42− selection were then synthesized through spatially and temporally controlling interfacial polymerization with modified ZIF-8 nanoparticles (tZIF-8) as aqueous phase additives or as interlayers. The effects of the embedding position of tZIF-8 on the structure, morphology, physicochemical properties, and performance of PA-based membranes were explored through a sequence of characterization techniques. The results revealed that the PA-based membrane with tZIF-8 embedded in the PA layer could achieve a high water permeance of 24.8 L m−2 h−1 bar−1 with a high retention of 99.4 % Na2SO4 and a Cl−/SO42− selectivity of 141, which was superior to most state-of-the-art PA-based membranes. Comparatively, the Cl−/SO42− selection of the PA-based membrane with tZIF-8 embedded between the PA layer and the substrate was 136, while the water permeance was slightly enhanced to 28.2 L m−2 h−1 bar−1. Excitingly, the resulting membranes all exhibit superior antifouling properties and stability. Our facile strategy for tuning membrane microstructures provides new ideals into the development of highly permeable and excellently selective PA-based membranes for precise ion sieving.

Ultrathin membranes comprising polymers of intrinsic microporosity oligomers for high-performance organic solvent nanofiltration

Microporous organic polymers (MOPs) featuring chemically rigid backbones and permanent micropores are desirable for fabricating molecular selective membranes towards organics separation. However, coordinating facile film processing with high micropore persistence remains a challenge. In this paper, a low molecular weight polymers of intrinsic microporosity was rationally designed by precisely controlling the stoichiometric equilibrium of polymerization monomer. The polymers of intrinsic microporosity oligomers combine rigid and contorted structures with the aqueous solution processability, promoting the formation of 25-nm-thick polyacrylamide nanofilms with enhanced microporosity via support-free interfacial polymerization (SFIP). The resulting composite membranes have superior retention of small molecular solutes and high nonpolar and polar solvent permeances. Experiment and simulation results show that their excellent separation performance is due to substantially open and interconnected microporosity formed in the polymer networks based on rigid and contorted diamines as well as reduced film thickness. This study provides a new sight for using MOPs to construct high-microporosity membranes for precise and rapid molecular sieving.

Thin film nanocomposite membranes based on renewable polymer Pebax® and zeolitic imidazolate frameworks for CO2/CH4 separation

This study investigates the impact of integrating Pebax® Rnew® 30R51, a sustainable elastomer-type copolymer material, with zeolitic imidazolate frameworks (ZIFs) to develop advanced membranes for CO2/CH4 gas separation. The fabrication process of ZIF/Pebax® Rnew® 30R51 thin films was optimized to achieve uniform and defect-free thin film composite (TFC) membranes. Crucial membrane properties, including permeability, selectivity and separation efficiency, were analyzed with variations in ZIF type, loading levels, film thickness and operating conditions. Additionally, the resulting TFC and ZIF/Pebax® Rnew® 30R51 thin film nanocomposite (TFN) membranes were subjected to characterization via FTIR, XRD, TGA and SEM to evaluate their physicochemical properties. Nanoparticles of ZIF-8, NH2-ZIF-8 and ZIF-94 were individually added (at 5–15 wt% loadings) to the Pebax® Rnew® 30R51 matrix to develop the CO2 separation efficiency. The pristine TFC membrane showed a 66 GPU CO2 permeance and a 37.5 CO2/CH4 separation selectivity, primarily due to improved CO2 mass transport. Upon inclusion of ZIFs, the CO2 permeance with 5 wt% loadings of ZIF-8, NH2-ZIF-8 and ZIF-94 increased to 148, 99 and 125 GPU, respectively, despite this, the CO2/CH4 separation selectivity maintained at 29.4, 37.0 and 27.0, respectively.

Toward a Circular Lithium Economy with Electrodialysis: Upcycling Spent Battery Leachates with Selective and Bipolar Ion-Exchange Membranes.

Recycling spent lithium-ion batteries offers a sustainable solution to reduce ecological degradation from mining and mitigate raw material shortages and price volatility. This study investigates using electrodialysis with selective and bipolar ion-exchange membranes to establish a circular economy for lithium-ion batteries. An experimental data set of over 1700 ion concentration measurements across five current densities, two solution compositions, and three pH levels supports the techno-economic analysis. Selective electrodialysis (SED) isolates lithium ions from battery leachates, yielding a 99% Li-pure retentate with 68.8% lithium retention, achieving relative ionic fluxes up to 2.41 for Li+ over transition metal cations and a selectivity of 5.64 over monovalent cations. Bipolar membrane electrodialysis (BMED) converts LiCl into high-purity LiOH and HCl, essential for battery remanufacturing and reducing acid consumption via acid recycling. High current densities reduce ion leakage, achieving lithium leakage as low as 0.03%, though hydronium and hydroxide leakage in BMED remains high at 11-20%. Our analysis projects LiOH production costs between USD 1.1 and 3.6 per kilogram, significantly lower than current prices. Optimal SED and BMED conditions are identified, emphasizing the need to control proton transport in BMED and improve cobalt-lithium separation in SED to enhance cost efficiency.

Landfill-gas-to-biomethane via a new carbon capture and utilization technology: One-pot sodium chloride batch mineralization

A new landfill-gas-to-biomethane route adopts a new carbon capture and utilization process via sodium chloride (NaCl) mineralization. The new process exports chlorine (Cl2), dense carbon dioxide (CO2), hydrogen (H2) and sodium carbonate (Na2CO3). Process absorbs CO2 from landfill-gas with aqueous NaOH/Na2CO3 in batch multi-purpose columns that execute several processing steps in one-pot; namely: CO2 absorption; sodium bicarbonate (NaHCO3) precipitation; NaHCO3 filtration driven by pressurized CO2; NaHCO3 breakage to Na2CO3 via hot CO2 injection; Na2CO3 cooling via cold CO2 injection; and solid Na2CO3 disposal through column lateral doors. The one-pot columns avoid investment with several steady-state complex equipment like bubble-columns, centrifuges, filters, solid dryers, heaters, mud pumps and solid transporters. The depleted solvent from the one-pot columns is regenerated via steady-state, high current-density, brine electrolysis wherein solvent continually feeds cathodes, while brine continually feeds anodes as sodium source. Sodium reaches the cathode through selective Flemion F9010 ion-exchange membrane. CO2 is partially mineralized to Na2CO3 and partially exported as supercritical CO2. Process output-ratios per captured CO2 are: 1.159kgNa2CO3/kg, 0.7754kgCl2/kg, 0.4299kgCH4/kg, 0.0219kgGREEN−H2/kg and 0.51875kgCO2/kg, while the input-ratios are 1.2782kgNaCl/kg, 0.197kgH2O/kg and 1.7495kWh/kg. The new landfill-gas-to-biomethane (480,000Nm3/d landfill-gas) was evaluated environmentally and techno-economically reaching 48.6MMUSD investment, 112MMUSD/y revenues and 418.34MMUSD net value (30 years).

Enhanced selectivity of SPEEK membrane incorporated covalent organic nanosheet crosslinked graphene oxide for vanadium redox flow battery

It is difficult for sulfonated poly(ether ether ketone) (SPEEK) to possess both high proton conduction and vanadium resistance owing to the degree of sulfonation. Herein, the composite membranes (S/GO-TpTG) with cationic covalent organic nanosheet (TpTG) crosslinked graphene oxide (GO-TpTG) are prepared to enhance selectivity by optimizing the ion transport channels. The GO-TpTG can efficiently transport protons utilizing its cationic porous structure and acid-base pairs' interaction with SPEEK. Meanwhile, it can block vanadium ions through the Donnan exclusion and physical blocking effects. The S/GO-TpTG membrane with 3 wt% GO-TpTG exhibits excellent proton conductivity (82.7 mS cm−1) and selectivity (77.9 × 10−7 cm2 min−1). The VRFB with this membrane exhibits excellent energy efficiency (88.6–81.0 % at 100–200 mA cm−2), cycle durability, and self-discharge time (209.8 h). This study confirms the great potential of GO-COF to balance proton conductivity and vanadium resistance, and provides an effective strategy to optimize proton channels.

Synthetic membrane selection for in vitro release testing (IVRT): A case study of topical mometasone furoate semi-solid dosage forms

In vitro release testing (IVRT) is extensively used to develop the formulation of topical semi-solid products, to evaluate the quality and consistency of the product after scale-up and post-approval changes, and more recently to aid the evaluation of topical generic products’ equivalency. The selection of synthetic membrane is one of the most critical parameters of the method development part of IVRT. It is well known that the membrane features namely its polymer matrices, porosity, pore size, thickness can have a substantial effect on the IVRT data. However, there is no detailed information available in the literature regarding the membrane selection for different types of topical dosage forms. Therefore, we aimed to investigate whether difference topical semi-solid dosage forms of the same drug molecule would cause to variation in the membrane selection. Within this framework, rheological behaviour of commercially available three different types of topical semi-solid dosage forms (ointment, cream, and lotion) of mometasone furoate (0.1%) were primarily characterized. Then, the membrane inertness test was conducted using a series of synthetic hydrophilic membranes (regenerated cellulose, cellulose acetate, cellulose nitrate, mixed cellulose ester membranes) and hydrophobic membranes (polyether sulfone, polypropylene, polytetrafluoroethylene membranes) after identifying of an appropriate receptor medium that ensures sink condition for mometasone furoate. Lastly, IVRT studies from the topical semi-solid products were performed utilizing Franz-type diffusion cells. The membrane inertness and in vitro release data demonstrated that the cellulose acetate membrane showed superior diffusion properties in general while the other synthetic membranes exhibited varying outcomes for different semi-solid dosage forms of mometasone furoate. Overall, the results indicated that the release rate and the cumulative drug released amount of drug after 6 h through the different synthetic membranes might vary depending on the semi-solid dosage form. In order to select the synthetic membrane for IVRT, it should also be considered potential interactions between the polymer matrices and the chemical structure of drug molecule as well as formulation components prior to conducting membrane inertness test and IVRT studies.