Search

The global freshwater shortage presents a modern challenge, prompting water management strategies in various sectors, notably the oil and gas industry. Addressing the escalating water cut from petroleum wells is paramount. This review delves into complexities surrounding water production in oil and gas, with a focus on membrane processes. The study analyses membrane technology types, materials, and modules, highlighting the achievements and gaps for future developments. It aims to elucidate challenges and advancements in membrane-based water treatment within this industry. Advancements should prioritise novel materials, module configurations, and manufacturing techniques to enhance performance and mitigate fouling. Considering the complexity of produced water, ongoing projects are vital to maintain membrane performance resilience. Environmental concerns emphasise the need for greener alternatives, urging research into hybrid processes and environmentally friendly energy sources for sustainable water treatment.

High performance polyamide nanofiltration membranes play important roles in Mg2+/Li+ separation and Li+ extraction, but they are prepared via multiple time‐/labor demanding steps. Both the scalability of these membranes and the engineering of membrane modules remain an elusive challenge. Here the design of a Gemini‐electrolyte monomer (GEM) featuring bidentate amine groups, quaternary ammonia, and endocyclic contorted conformation is reported. The monomer's low interfacial diffusivity is balanced by high condensational reactivity during its interfacial polymerization with trimesoyl chloride (TMC), leading to the straightforward formation of defect‐free, ≈14 nm thick membranes. The membrane shows the highest permeance (≈19.2 L m−2 h−1 bar−1) among Mg2+/Li+ nanofiltration membranes prepared via straightforward interfacial polymerization without post‐modification, combined with good Mg2+/Li+ selectivity (≈15.4) and stability. The validity of GEM design is verified by control monomers. Large‐area (1 × 2 m2) GEM‐TMC membranes and spiral‐wound modules (effective area: 0.5 m2) are prepared, both of which show reproducible and high performance. [ABSTRACT FROM AUTHOR]

Membrane chromatography is mainly used for the separation and purification of proteins and biological macromolecules in the downstream processing process, also applications in sewage disposal. Membrane chromatography is recognized as an effective alternative to column chromatography because it significantly improves chromatography from affinity, hydrophobicity, and ion exchange; the development status of membrane chromatography in membrane matrix and membrane equipment is thoroughly discussed, and the applications of protein capture and intermediate purification, virus, monoclonal antibody purification, water treatment, and others are summarized. This review will provide value for the exploration and potential application of membrane chromatography. [ABSTRACT FROM AUTHOR]

• Recent developments in Metal–organic framework-based mixed matrix membranes for hydrogen separation were summarized. • An in-depth discussion on fabrication and modification strategies for H 2 /N 2 , H 2 /CH 4 , and H 2 /CO 2 separation was presented. • Advanced characterization techniques for studying the MOF-polymer interface. • The separation performance under harsh conditions and improvements in robustness and durability were emphasized. • The outlook and future directions for MOF-based MMMs were proposed. Membrane separation is one of the low-energy hydrogen purification technologies that effectively mitigates the carbon footprint and is eco-friendly process for large-scale integration. Conventional membranes, such as polymeric ones, typically suffer from the trade-off between permeability and selectivity demonstrated by the Robeson's upper bound. Metal organic frameworks (MOFs) are recognized as promising fillers to fabricate the mixed matrix membranes (MMMs) for hydrogen separation due to their high porosity, large internal surface area, and structural tunability. Herein, this review offers a comprehensive summary of the related literature that explores the challenges in developing MMMs, and presents an in-depth discussion on fabrication and modification strategies of MOF-based MMMs specifically for H 2 /N 2 , H 2 /CH 4 , and H 2 /CO 2 separation. Advanced characterization techniques for understanding membrane properties, specifically the MOF–polymer interface, are outlined. Subsequently, the hydrogen separation performance of MOF-based MMMs under harsh operating conditions and improvement in robustness and long-term durability properties are emphasized. The outlook and future directions for MOF-based MMMs are also proposed. It is anticipated that this review will serve as a stepping stone for the coming MOF-based MMMs research on sustainable and large-scale application for hydrogen separation. [ABSTRACT FROM AUTHOR]

Natural gas consists of a mixture of hydrocarbons with the largest share of methane, and non-hydrocarbon impure components such as N2, CO2 and H2S. In order to fulfill the gas market requirements, it is necessary to separate these unwanted components from the natural gas stream. There are several available technologies for the separation of CO2 from natural gas, such as: polymeric membranes, cryogenic distillation, absorption and adsorption. In this paper is presented the mechanism of CO2 separation using membrane technology, as well as the process of separation CO2 depending on the number of membranes in the system for a typical gas reservoir in Serbia.

High-fidelity simulations of momentum and mass transfer within a hollow fiber gas separation membrane module are here reported. The simulations capture the potential detrimental effects of poor fiber packing at the bundle–case interface on fluid distribution and performance. Results are presented for both circular and planar fiber bundles. The length over which bundle–case gaps affects flow is determined. The length increases dramatically with increasing fiber packing fraction. As the packing fraction approaches 0.6, the impact extends over the entire bundle diameter for small modules (

Membrane Distillation (MD) is a membrane-based, temperature-driven water reclamation process. While research emphasis has been largely on membrane design, upscaling of MD has prompted advancements in energy-efficient module design and configurations. Apart from the four conventional configurations, researchers have come up with novel MD membrane module designs and configurations to improve thermal efficiency. While membrane design has been the focus of many studies, development of appropriate system configurations for optimal energy efficiency for each application has received considerable attention, and is a critical aspect in advancing MD configurations. This review assesses advancements in modified and novel MD configurations design with emphasis on the effects of upscaling and pilot scale studies. Improved MD configurations discussed in this review are the material gap MD, conductive gap MD, permeate gap MD, vacuum-enhanced AGMD/DCMD, submerged MD, flashed-feed MD, dead-end MD, and vacuum-enhanced multi-effect MD. All of these modified MD configurations are designed either to reduce the heat loss by mitigating the temperature polarization or to improve the mass transfer and permeate flux. Vacuum-enhanced MD processes and MD process with non-contact feed solution show promise at the lab-scale and must be further investigated. Hollow fiber membrane-based pilot scale modules have not yet been sufficiently explored. In addition, comparison of various configurations is prevented by a lack of standardized testing conditions. We also reflect on recent pilot scale studies, ongoing hurdles in commercialization, and niche applications of the MD process.

Membrane-based separation of oxygen (O 2) and nitrogen (N 2) has emerged as an essential technological advancement with far-reaching implications across a multitude of industries. This comprehensive review explores the dynamic landscape of progress and challenges associated with this innovative approach to gas separation. The introductory section discusses deeply the rationale for employing membranes in gas separation processes. It underscores the key factors driving the evolution of this field, which encompass the development of sophisticated membrane modules, the exploration of state-of-the-art materials, the tailoring of membrane morphology, and the adoption of advanced manufacturing techniques. Subsequently, this article navigates through the intricate realm of membrane materials and synthesis methods, offering valuable insights into the selection of materials and the intricacies of fabrication techniques, including phase inversion and electrospinning. The analysis of gas transport within membranes aims to provide a comprehensive understanding of the fundamental principles that underlie efficient O 2 and N 2 separation. A thorough exploration of various membrane types and modules offers a detailed perspective on asymmetric membranes, mixed matrix membranes, block copolymer membranes, and various modified membranes, such as those incorporating metal-organic frameworks, zeolites, and carbon molecular sieves. Furthermore, this review meticulously dissects the impact of critical separation parameters, including feed composition, flow rate, temperature, and pressure, on separation efficiency. The article also spotlights recent breakthroughs and enhancements in the performance of membrane-based O 2 and N 2 separation, demonstrating the continued advancements in this field. Finally, it assesses the current state of progress, identifies existing challenges, and outlines the promising future prospects for membrane-based O 2 and N 2 separation technology. [Display omitted] • Membrane technology promises green gas separation, revolutionizing industries. • Review shows O 2 /N 2 separation: modules, materials, morphology, and manufacturing. • Review highlights material selection and fabrication intricacies. • Transport analysis drives O 2 /N 2 separation advancements. • Review examines membrane types, spotlighting O 2 /N 2 breakthroughs. [ABSTRACT FROM AUTHOR]

Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide (CO2) from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly(ethylene oxide)-containing block copolymers such as Pebax® or PolyActive™ polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActive™ polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m3(STP)·(m2·h·bar)−1 (1 bar = 105 Pa) at a carbon dioxide/nitrogen (CO2/N2) selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into flat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActive™ polymer as a membrane material for industrial-scale gas processing.

Cyanide is one of the main reagents used in gold mining that can be recovered to reduce operational costs. Gas membrane technology is an attractive method for intensifying both the stripping and absorption processes of valuable compounds, such as cyanide. However, scaling-up this technology from laboratory to industry is an unsolved challenge because it requires the improvement of the experimental methodologies that replicate lab-scale results at a larger scale. With this purpose in mind, this study compares the performance of three different hollow fiber membrane contactor modules (1.7 × 5.5 Mini Module, 1.7 × 10 Mini Module, and 2.5 × 8 Extra Flow). These are used for recovering cyanide from aqueous solutions at laboratory scale, using identical operational conditions. For each experimental set-up, mass-transfer correlations at the ranges of feed flows assayed were determined. The modules with the smallest and largest area of mass transfer reached similar cyanide recoveries (>95% at 60 min), which demonstrate the impact of module configuration on their operating performance. The results obtained here are limited for scaling-up the membrane module performance only because operating modules with the largest area results in a low Re number. This fact limits the extrapolation of results from the mass-transfer correlation.

A performance simulator of spiral wound membrane (SWM) modules used for desalination is a valuable tool for process design and optimization. The existing state-of-the-art mesoscale simulation tools account for the spatial non-uniformities created by the operation itself (flow, pressure, and concentration distributions) but they assume uniform membrane properties. However, experimental studies reveal that membrane properties are by no means uniform. Therefore, the need arises to account for this non-uniformity in simulation tools thus enabling a systematic assessment of its impact, among other benefits; a first step toward this goal is presented herein. In particular, the issue of an organic fouling layer growing on a membrane with non-uniform permeability is analyzed. Several mathematical treatments of the problem are discussed and indicative results are presented. The concept of fouling layer thickness probability density function is suggested as a means to introduce sub-grid level calculations in existing simulation tools. The analysis leads to the selection of an appropriate methodology to incorporate this effect in the dynamic simulation of fouling layer evolution at the membrane-sheet scale.

• A review on membranes for separation of energy-relevant gas mixtures is timely reported. • The opportunities and challenges in applying porous materials in membranes are declared. • A discussion on limitations and possible improvements of the current membrane systems is addressed. • Key aspects in highly intensified membrane modules is provided. Membranes containing nanoporous materials (such as zeolites, metal–organic materials and 2D materials such as graphene derivatives) may allow more efficient separation of gas mixtures relevant to emerging energy technologies. For example, such membranes could be applied in the separation of gases containing mixtures of carbon dioxide (CO 2) and hydrogen (H 2). However, these membranes are currently at a relatively low technology readiness level. Hence, here we review the opportunities and challenges of applying these porous materials in practice and at scale in membranes for possible commercialization. Besides, we highlight the necessity of improvements in the porosity control of 2D materials and the decrease in the selective membrane skin layer when adapted in asymmetric membranes. In this latter point, we declare the main limitations of porous supports, as well as the further developments needed in the gutter layer and supports. Additionally, we review the main membrane module configurations and process requirements, declaring the most suitable configurations (e.g. spiral wound and hollow fiber modules) at scale with promising future for highly intensified membrane modules for application in CO 2 and H 2 separations. Finally, apart from the conclusions derived from this review, we outline useful recommendations for the researchers in the field. [ABSTRACT FROM AUTHOR]

Membrane-based water treatment processes have been established as a powerful approach for clean water production. However, despite the significant advances made in terms of rejection and flux, provision of sustainable and energy-efficient water production is restricted by the inevitable issue of membrane fouling, known to be the major contributor to the elevated operating costs due to frequent chemical cleaning, increased transmembrane resistance, and deterioration of permeate flux. This review provides an overview of fouling control strategies in different membrane processes, such as microfiltration, ultrafiltration, membrane bioreactors, and desalination via reverse osmosis and forward osmosis. Insights into the recent advancements are discussed and efforts made in terms of membrane development, modules arrangement, process optimization, feed pretreatment, and fouling monitoring are highlighted to evaluate their overall impact in energy- and cost-effective water treatment. Major findings in four key aspects are presented, including membrane surface modification, modules design, process integration, and fouling monitoring. Among the above mentioned anti-fouling strategies, a large part of research has been focused on membrane surface modifications using a number of anti-fouling materials whereas much less research has been devoted to membrane module advancements and in-situ fouling monitoring and control. At the end, a critical analysis is provided for each anti-fouling strategy and a rationale framework is provided for design of efficient membranes and process for water treatment. [Display omitted] • A comprehensive review focusing on various fouling control strategies applied in water treatment. • Membrane surface has been modified via patterning and various anti-fouling materials. • Technological advancements in membranes modules and process design largely impact performance. • In-situ fouling detection and control can further support sustainable process design. [ABSTRACT FROM AUTHOR]

• Cup-like SCA4 and STCAss molecules were incorporated into the polyamide network. • Both cup-like calixarenes effectively reduced the reverse solute flux and improved the selectivity of PRO membranes. • 1-inch TFN hollow fiber membrane modules were fabricated for PRO. • The SCA4 incorporated membrane was more efficient in maintaining power density in long-term PRO tests. Osmotic energy is released when mixing solutions with different salinities. Pressure retarded osmosis (PRO) is a promising membrane technology to harvest this osmotic energy. However, the current polymeric PRO membranes suffer from the high reverse solute fluxes during PRO processes, which would dramatically diminish the membrane performance, especially in big membrane modules. In order to control the reverse solute flux, two cup-like calix[ n ]arenes, sulfocalix[4]arene (SCA4) and sulfothiacalix[4]arene (STCAss) were incorporated into the polyamide network to enhance the PRO performance of thin-film nanocomposite (TFN) hollow fiber membranes in 1-inch modules. Due to the unique structures and the enhanced molecular-sieving abilities of both macrocyclic molecules, they were able to effectively improve the selectivity of the resultant TFN hollow fiber membranes. After optimizing the concentration of each nano-filler, it was found that the TFN membrane with 0.20 wt% of STCAss produced a PRO power density of 15.0 W/m2 and a reverse salt flux of 28.3 gMH, while the other containing 0.10 wt% of SCA4 produced a PRO power density of 14.2 W/m2 and a reverse salt flux of 31.6 gMH. In long-term PRO tests at 20 bar, the SCA4-incorporated membrane was more efficient in controlling the concentration polarization (CP) and maintaining the power density comparing to the STCAss membrane because the former has a smaller cavity opening than the latter. This research work may provide useful insights to further design PRO membranes and membrane modules for osmotic power generation. [ABSTRACT FROM AUTHOR]

High-fidelity simulations of momentum and mass transfer within a hollow fiber gas separation membrane module are here reported. The simulations capture the potential detrimental effects of poor fiber packing at the bundle−case interface on fluid distribution and performance. Results are presented for both circular and planar fiber bundles. The length over which bundle−case gaps affects flow is determined. The length increases dramatically with increasing fiber packing fraction. As the packing fraction approaches 0.6, the impact extends over the entire bundle diameter for small modules (<1000 fibers). The results clearly demonstrate the detrimental effect of poor packing along the case and can be used to develop module manufacturing guidelines. To reduce computational costs, an equivalent planar bundle module approximation is developed. The approximate simulations agree well with results from full 3-D simulations and can reduce computational costs without sacrificing fidelity.

Modeling the operation of spiral-wound membrane modules is essential for their successful design and optimization. Such models must include the main types of membrane fouling, degrading desalination plant performance, including scaling due to sparingly soluble salts. Unfortunately, the complexity of underlying physicochemical processes and the coexistence of several spatial and temporal scales render intractable modeling of membrane scaling based on first principles. Therefore, a suitable (albeit simplified) framework is developed for incorporating scaling dynamics into a fluid flow model formulated at an intermediate (i.e., mesoscopic) length scale of membrane operation. The general mesoscopic approach involves integration of spatially distributed submodels, thereby allowing predictions at the large (entire membrane sheet) scale; these submodels comprise constitutive laws and kinetic rate expressions derived at fine scales. A submodel for the effect of pre-existing bulk particles on scale formation is developed herein. Several numerical results are presented to exemplify the potential of the proposed framework. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2917-2927, 2013 [ABSTRACT FROM AUTHOR]

A review on pulp and paper industrial membrane processes using a variety of modules and processes is presented. Membranes are mostly used today to purify process waters and to recover coating colours. Ultrafiltration using tubular membrane modules or cross-rotational (CR) filtration has been widely applied for the purification of process waters. The reuse of UF membrane permeate has decreased the fresh water consumption to lower than 6m3/t of paper in some paper machines. Some industrial membrane processes also recover valuable products from different streams (e.g lignosulphonates). Membranes are also combined with biological degradation processes in some paper mills. Nanofiltration has been used to purify the effluents discharged from the activated sludge process. At least two reverse osmosis plants purify river water to be used as raw water in the mill. Furthermore, advantages of different membrane modules and the current ways to treat membrane concentrate are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Spacers are designed to generate significant secondary flow structures and create directional changes in the flow through membrane modules. Shape of the spacers used in membrane modules strongly influences the resulting flow and therefore performance of the module. In this work fluid dynamics of rectangular channels similar to membrane modules and containing different spacers was simulated using a three-dimensional computational fluid dynamics (CFD) model. A ‘unit cell’ approach was evaluated and used for this purpose. In addition to predicting the pressure drop, the simulated results provided significant insight into fluid dynamics of spacer filled channels. The validated CFD model was used to evaluate performance of different spacer shapes and understand the role of spacer shape and resulting fluid dynamics. The models were extended for the first time to simulate flow in spacer filled curvilinear channels, which could be useful in understanding the fluid behavior in spiral modules. The results were compared with those obtained with the flat channel. The approach and results presented in this work will have significant implications for identifying improved spacers with higher propensities to reduce fouling in membrane modules. [Copyright &y& Elsevier]

A mathematical model is derived to simulate the performance of spiral wound membrane modules for the pervaporative separation of binary liquid mixtures. Permeation through the polymer membrane is described by a detailed solution–diffusion model. Flory–Huggins theory is used to predict solubility of the penetrants, while the composition and temperature dependence of the diffusion coefficients are described by phenomenological relations. Unknown parameters of the solution–diffusion model are determined from sorption and flux data using nonlinear least-squares estimation. Standard correlations are used to estimate the mass transfer resistance due to the liquid boundary layer on the feed side of the module. The solution–diffusion model is coupled to differential mass, momentum and energy balances on the feed and permeate sides of the module to predict separation performance. The resulting model is two-dimensional as the feed-side and permeate-side stream properties vary in both the feed and permeate flow directions. Required input data to the model includes the feed flow rate, composition and temperature, the outlet permeate pressure, the membrane properties and the module dimensions. A numerical solution technique based on the use of the shooting method in the permeate flow direction and numerical integration in the feed flow direction is proposed. The model yields predictions of the feed-side and permeate-side stream properties as a function of both spatial coordinates. The separation of styrene and ethylbenzene with a polyurethane membrane is used to illustrate the modeling approach. A single module and a 10-module system with interstage heating are simulated to demonstrate potential uses of the pervaporation model. [Copyright &y& Elsevier]

Nanofiltration (NF) has been widely used for sulphate removal in chlor-alkali industries and concentrating ingredients in pharmaceutical industries, but the fabrication and applications of thin-film composite (TFC) NF hollow fiber membranes and modules are still lagged behind those NF membranes in other configurations. In this work, the pressure-assisted interfacial polymerization (IP) is employed to fabricate TFC NF hollow fiber membranes in 1-inch modules through tailoring the reaction conditions. By firstly circulating a piperazine (PIP) solution in the lumen side under a positive pressure and then circulating a trimesoyl chloride (TMC) solution at atmosphere pressure, a strong, uniform and defect-free polyamide selective layer is formed on the inner surface of hollow fiber membranes. The optimal TFC NF hollow fiber membranes in 1-inch modules exhibit a pure water permeability of 8.93 L m−2 h−1 bar−1 and a molecular weight cut-off (MWCO) of 175 Da. They also show a rejection of 98.3% to MgSO 4 and a high rejection of around 98% to cephalexin (molecular weight = 437 g mol−1). The optimal membranes exhibit a consistent Na 2 SO 4 rejection of ∼85% and nearly no NaCl rejection over a 30-day performance test using a high salinity feed solution containing 200 g/L NaCl and 10 g/L Na 2 SO 4. The impressive performance suggests that the newly developed TFC NF hollow fiber membrane has great potential to be used in the chlor-alkali and pharmaceutical industries. [Display omitted] • 1-inch TFC NF hollow fiber membrane modules have been designed and fabricated. • The optimal membrane exhibits a PWP of 8.93 L m−2 h−1 bar−1 and a MWCO of 175 Da. • It also shows a MgSO 4 rejection of 98.3% and a high rejection of 98% to cephalexin. • It displays outstanding performances to remove SO 4 2− from the high salinity brine. [ABSTRACT FROM AUTHOR]

Membrane Distillation (MD) is a membrane-based, temperature-driven water reclamation process. While research emphasis has been largely on membrane design, upscaling of MD has prompted advancements in energy-efficient module design and configurations. Apart from the four conventional configurations, researchers have come up with novel MD membrane module designs and configurations to improve thermal efficiency. While membrane design has been the focus of many studies, development of appropriate system configurations for optimal energy efficiency for each application has received considerable attention, and is a critical aspect in advancing MD configurations. This review assesses advancements in modified and novel MD configurations design with emphasis on the effects of upscaling and pilot scale studies. Improved MD configurations discussed in this review are the material gap MD, conductive gap MD, permeate gap MD, vacuum-enhanced AGMD/DCMD, submerged MD, flashed-feed MD, dead-end MD, and vacuum-enhanced multi-effect MD. All of these modified MD configurations are designed either to reduce the heat loss by mitigating the temperature polarization or to improve the mass transfer and permeate flux. Vacuum-enhanced MD processes and MD process with non-contact feed solution show promise at the lab-scale and must be further investigated. Hollow fiber membrane-based pilot scale modules have not yet been sufficiently explored. In addition, comparison of various configurations is prevented by a lack of standardized testing conditions. We also reflect on recent pilot scale studies, ongoing hurdles in commercialization, and niche applications of the MD process.

The development of commercial-scale thin-film composite (TFC) hollow fiber membranes and modules for reverse osmosis (RO) has been lagging behind spiral wound TFC flat-sheet membranes and modules for many years. The delay arises from the challenges of synthesizing a defect-free polyamide selective layer on hollow fibers in modules. In order to solve this problem, a novel interfacial polymerization method is presented in this work to fabricate 1-inch TFC hollow fiber membrane modules for RO applications. By circulating the m-phenylenediamine (MPD) solution on the lumen side under a positive pressure and circulating the trimesoyl chloride (TMC) solution at the atmosphere pressure, a strong, uniform and defect-free polyamide selective layer is formed on the inner surface of hollow fiber membranes in modules. Under pressure, not only MPD monomers are evenly distributed on the inner surface of each hollow fiber substrate in modules, but also sufficient MPD monomers can retain in the substrate pores for further reaction with TMC monomers. The best RO performance obtained by this newly developed TFC hollow fiber membrane module has a water permeability of 4.49 L m−2 h−1 bar−1 and a NaCl rejection of ~99%, using a feed solution of 1000 ppm NaCl under a transmembrane pressure of 20 bar. The novel interfacial polymerization method may provide useful insights to fabricate TFC hollow fiber membrane modules for desalination of brackish water. [Display omitted] • A novel IP method was developed to fabricate 1-inch TFC hollow fiber membrane module. • A defect-free polyamide was formed on the inner surface of 200 fibers in each module. • Fabrication of TFC hollow fibers in 1-inch modules was optimized for RO applications. • The highest RO water permeability is 4.49 LMH/bar with a NaCl rejection of ~99%. [ABSTRACT FROM AUTHOR]

Mixed-matrix membranes (MMMs) have shown promising performances for gas separation, in particular, propylene/propane separation. Their commercial applications require to fabricate MMMs in scalable forms, i.e., asymmetric mixed-matrix hollow fiber membranes (MMHFMs). Up until now, however, there have been few reports on MMHFMs due to the fundamental engineering challenges associated with current fiber spinning processes using filler-suspended dope solutions. Recently, we proposed a scalable MMM fabrication strategy, namely polymer-modification-enabled in-situ metal-organic framework formation (PMMOF). The PMMOF has potential to overcome some of the engineering challenges since it decouples hollow fiber spinning step and MMM formation step. Herein, we report asymmetric 6FDA-DAM (4,4′-(hexafluoroisopropylidene) diphthalic anhydride-2,4,6-trimethyl-1,3-diaminobenzene)/ZIF-8 MMHFM modules by transforming 6FDA-DAM coated hollow fiber membrane (HFM) modules using the PMMOF. The resulting asymmetric MMHFM modules showed a promising propylene/propane separation performance (i.e., propylene permeance of ~2.15 GPU and separation factor of ~23.4) without additional defect healing steps. The membranes showed stable separation performance over a period of up to 25 days and at the total feed pressures of up to 6 bar. Finally, we demonstrated MMHFM modules consisting of up to seven individual fiber strands. To the best of our knowledge, this is the first multi-strand MMHFM modules showing promising propylene/propane separation performances, thereby opening up the possibility of the commercial applications of MMMs. • A preformed polymer hollow fiber membrane module was directly converted to a mixed-matrix hollow fiber membrane module. • The prepared MMHFM exhibited the thinnest skin layers among the MMHFMs reported. • The as-prepared MMHFM showed promising C3 separation performances with enhanced resistances to aging and plasticization. • The first multi-strand MMHFM module was successfully demonstrated. [ABSTRACT FROM AUTHOR]

Previous research on forward osmosis (FO) has largely focused on developing new membranes with novel materials or structures. Many of these membranes, while performing well in the lab, have not seen commercial success. One of the barriers to commercialization is rooted in the discrepancy of membrane performance at a lab scale compared to that at module scale. To understand the relationship between lab-scale and module-scale membrane performance, this study presents a comprehensive and experimentally verified computational fluid dynamics (CFD) model that establishes relationships between membrane/module properties and overall module performance. The model was developed for hollow fiber membrane modules and experimentally verified and used to conduct simulations to quantify membrane and module property-performance relationships that impact osmotic flux performance. This work illustrates the development and use of an accessible modeling tool for the prediction of module performance and rational product design for forward osmosis membranes and modules. • A CFD model was developed to predict the FO performance of hollow fiber modules. • The model accuracy was experimentally verified using experimental data. • A number of membrane, module, and operational variables are studied. • The importance of some membrane properties are diminished at module scale. [ABSTRACT FROM AUTHOR]

Cyanide is one of the main reagents used in gold mining that can be recovered to reduce operational costs. Gas membrane technology is an attractive method for intensifying both the stripping and absorption processes of valuable compounds, such as cyanide. However, scaling-up this technology from laboratory to industry is an unsolved challenge because it requires the improvement of the experimental methodologies that replicate lab-scale results at a larger scale. With this purpose in mind, this study compares the performance of three different hollow fiber membrane contactor modules (1.7 × 5.5 Mini Module, 1.7 × 10 Mini Module, and 2.5 × 8 Extra Flow). These are used for recovering cyanide from aqueous solutions at laboratory scale, using identical operational conditions. For each experimental set-up, mass-transfer correlations at the ranges of feed flows assayed were determined. The modules with the smallest and largest area of mass transfer reached similar cyanide recoveries (>95% at 60 min), which demonstrate the impact of module configuration on their operating performance. The results obtained here are limited for scaling-up the membrane module performance only because operating modules with the largest area results in a low Re number. This fact limits the extrapolation of results from the mass-transfer correlation. [ABSTRACT FROM AUTHOR]

More than two decades after the highly-cited review on microfiltration of suspensions and macromolecular solutions, it is time to revisit and update the fundamentals and applications of this topic. This includes addressing inevitable fouling phenomena, the description of fouling, fouling models, means to mitigate fouling and the modernization of membrane modules. Mass transfer limitations, related to concentration polarization and fouling, remain the Achilles' heel. Since empirical expressions that describe fouling offer limited predictive ability and mechanistic insight, there is an urgent need for more in-depth fundamental understanding. Elucidating interfacial interaction energies has gained much attention in recent years; the DLVO model (and its extension) has been validated for a wide range of foulants. The use of molecular dynamics simulations to model transport and fouling represents a major advance, providing insights not possible through experiments. Building on classical fouling mechanisms, new models hold promise to provide more realistic description of fouling phenomena. Fouling mitigation efforts have focused on high-throughput modification platforms and more energy-efficient unsteady-state shear methods. Finally, membrane modules can be modernized based on the knowledge accumulated to better improve their efficiency, and factoring in important considerations like feed type, mechanical stability, hydrodynamics, economics and application goals. Image 1 • Describes advances in microporous membranes, fouling, analytical model and module. • Reveals that high throughput and machine learning will expedite optimization. • Indicates that interaction energy analysis is critical for better fouling prediction. • Demonstrates combined fouling models can often predict fouling accurately. • Reports that unsteady flow reduces concentration polarization/fouling. [ABSTRACT FROM AUTHOR]