Membrane Processes Research Articles

Effect of hollow fiber membrane packing on the performance of modules formed with fiber tows

ABSTRACT Membrane processes are being considered for carbon dioxide capture from concentrated point sources. The processes often use hollow fiber membranes. Modules are formed by gathering fibers together in a bundle. The fibers may be supplied individually or in small groups (i.e. tows) for module fabrication. The use of tows can introduce nonuniform fiber packing due to the size and spacing of the tows. The potential for flow maldistribution and its detrimental effect on module performance is evaluated by solving the governing conservation equations. For the first time, the performance of a module formed from fiber tows is evaluated. Two performance metrics are reported: 1) recovery and 2) required area as a function of carbon dioxide removal. The effects of tow size and tow spacing are evaluated. The results indicate performance is better for smaller tows. Furthermore, lower packings, both intra- and inter-tow, are preferred. The concept of an equivalent planar bundle (EPB) for fiber tow modules is introduced to potentially reduce simulation time and costs. The simple procedure for creating the EPB is validated by comparing the performance metrics calculated using the EPB to the results obtained from full simulations.

Pharmaceutical Removal with Photocatalytically Active Nanocomposite Membranes

The advancement of pharmaceutical science has resulted in the development of numerous tailor-made compounds, i.e., pharmaceuticals, tuned for specific drug targets. These compounds are often characterized by their low biodegradability and are commonly excreted to a certain extent unchanged from the human body. Due to their low biodegradability, these compounds represent a significant challenge to wastewater treatment plants. Often, these compounds end up in effluents in the environment. With the advancement of membrane technologies and advanced oxidation processes, photocatalysis in particular, a synergistic approach between the two was recognized and embraced. These hybrid advanced water treatment processes are the focus of this review, specifically the removal of pharmaceuticals from water using a combination of a photocatalyst and pressure membrane process, such as reverse osmosis or nanofiltration employing photocatalytic nanocomposite membranes.

Efficient and Green Recovery of Lithium from Spent Lithium-Ion Batteries Based on a Multipotential Field Membrane Process Intensification

Efficient and Green Recovery of Lithium from Spent Lithium-Ion Batteries Based on a Multipotential Field Membrane Process Intensification

Computational Fluid Dynamics Modeling of Pressure-Retarded Osmosis: Towards a Virtual Lab for Osmotic-Driven Process Simulations

Pressure-Retarded Osmosis (PRO) is an osmotically driven membrane-based process that has recently garnered significant attention from researchers due to its potential for clean energy harvesting from salinity gradients. The complex interactions between mixed-mode channel flows and osmotic fluxes in real PRO membrane modules necessitate high-fidelity modeling approaches. In this work, an efficient CFD framework is developed for the 3D simulation of osmotically driven membrane processes. This approach is based on a two-way coupling between a CFD solver, which captures external concentration polarization (ECP) effects, and an analytical representation of internal concentration polarization (ICP). Consequently, the osmotic water flux and reverse salt flux (RSF) can be accurately determined, accounting for all CP effects without any limitations on the geometrical complexity of the membrane chamber or its flow mode/regime. The proposed model is validated against experimental data, showing good agreement across various PRO case studies. Additionally, the model’s flexibility to simulate other types of osmotically driven processes such as forward osmosis (FO) is examined. Thus, the contributions of ECP and ICP effects in local osmotic pressure drop along the membrane chamber are comprehensively compared for FO and PRO modes. Finally, the capability of the CFD model to simulate a lab-scale PRO module is demonstrated across a range of Reynolds numbers from low-speed laminar up to turbulent flow regimes.

Combined Effects of Surface Roughness, Solubility Parameters, and Hydrophilicity on Biofouling of Reverse Osmosis Membranes

The fouling of protein on the surface of reverse osmosis (RO) membranes is a surface phenomenon strongly dependent on the physical and chemical characteristics of both the membrane surface and the foulant molecule. Much of the focus on fouling mitigation is on the synthesis of more hydrophilic membrane materials. However, hydrophilicity is only one of several factors affecting foulant attachment. A more systematic and rationalized methodology is needed to screen the membrane materials for the synthesis of fouling-resistant materials, which will ensure the prevention of the accumulation of foulants on the membrane surfaces, avoiding the trial and error methodology used in most membrane synthesis in the literature. If a clear correlation is found between various membrane surface properties, in combination or singly, and the amount of fouling, this will facilitate the establishment of a systematic strategy of screening materials and enhance the selection of membrane materials and therefore will reflect on the efficiency of the membrane process. In this work, eight commercial reverse osmosis membranes were tested for bovine serum albumin (BSA) protein fouling. The work here focused on three surface membrane properties: the surface roughness, the water contact angle (hydrophilicity), and finally the Hansen solubility parameter (HSP) distance between the foulant understudy (BSA protein) and the membrane surface. The HSP distance was investigated as it represented the affinities of materials to each other, and therefore, it was believed to have an important contribution to the tendency of foulant to stick to the surface of the membrane. The results showed that the surface roughness and the HSP distance contributed to membrane fouling more than the hydrophilicity. We recommend taking into account the HSP distance between the membrane material and foulants when selecting membrane materials.

Analysis on pollutants removal and sludge characteristics of a novel two-phase anaerobic/aerobic/integrated deoxygenated and anoxic reactor associated with membrane process for treating pesticide wastewater

Most frequently used biological method was improved anaerobic/anoxic/aerobic (A/A/O) process for treating actual pesticide wastewater presently. However, the effluent results were far away from what the national standard expects due to pesticide wastewater characteristics of high COD concentration, high total nitrogen (TN) concentration and high toxicity. In this study, a novel two-phase anaerobic/aerobic/integrated deoxygenated and anoxic reactor associated with membrane process (P1) were regarded as excellent candidates for the treatment of pesticide wastewater, compared the removal efficiency of pollutants with improved A/A/O process (P2) under different hydraulic retention times (HRTs). Effluent ethylene thiourea (ETU) concentration was reduced effectively by 67.1 % in P1. The average cyanide (CN−) effluent concentration in P1 and P2 was 0.40 mg/L and 6.67 mg/L, respectively. During the entire HRT change period, P1 significantly increased the biological oxygen demand (BOD5) removal efficiency by 12.98 %. The average effluent COD concentration of P1 was 36.41 mg/L, while that of P2 was 984.42 mg/L. In addition, TN removal efficiency of P1 exhibited distinct superiority. When HRT was 72 h, the average TN effluent concentration of P1 and P2 was 12.67 mg/L and 67.66 mg/L. The sludge performance indicators have been determined and results showed that the sludge viscosity of the membrane reactor in P1 had merely 32.6 % higher than that of the secondary sedimentation tank in P2, and the average vertical displacement of sludge settleability in P1 was 23.0 % slight lower than that of P2. The overall sludge performance proved that higher sludge concentration was allowed in P1. Moreover, experiment improved nitrite reductase (NIR) and nitrate reductase (NAR) in P1 were less susceptible to be suppressed by ETU and CN− increase compared with P2. Finally, the positive correlation relationship of sludge settleability with ETU and CN− has been identified successfully in P1.

Characterization and evaluation of the recovery process of saturated reverse osmosis membranes by chemical oxidation

Characterization and evaluation of the recovery process of saturated reverse osmosis membranes by chemical oxidation

Integrated Emulsion Liquid Membrane Process for Enhanced Silver Recovery from Copper-Silver Leached Solution

Integrated Emulsion Liquid Membrane Process for Enhanced Silver Recovery from Copper-Silver Leached Solution

Ladder electrodialysis: Efficient up-concentration of lithium ion and its mechanisms behind

The development of lithium extraction technology from salt lakes has seen significant demand in recent years, driven by the surge in energy storage needs for lithium-ion batteries used in electric vehicles and renewable power plants. Currently, evaporation technologies such as Mechanical Vapor Recompression (MVR) and Multi-Effect Distillation (MED) are commonly employed to concentrate lithium chloride for subsequent lithium carbonate precipitation. However, these evaporation methods limit lithium yield and increase capital and operational costs, particularly in high latitude areas. Pressure-driven membrane processes like reverse osmosis are hindered by concentration polarization and cannot significantly increase lithium chloride concentration. This study proposes a new membrane stack configuration with a laddered compartment design, termed Ladder Electrodialysis (LED), which addresses the concentration polarization issue and achieves a lithium salt (LiCl) concentration of 16.39 % (196 g·L−1). Economic analysis shows that the energy consumption is only 0.42 kWh per kilogram of LiCl. Ladder electrodialysis is a novel salt concentration technology, with applications in brine valorization or disposal.

Effect of channel roughness on the particle diffusion and permeability of carbon nanotubes in reverse electrodialysis process applying molecular dynamics simulation

Innovative technology and methods are crucial for making pure and refreshing water. Two main methods are present to delete soluble salts from water: membrane processes and thermal processes. A beneficial membrane technique is reverse electrodialysis. This research used molecular dynamics (MD) simulation to investigate how channel roughness affected particle diffusion and permeability in carbon nanotubes (CNTs) via the reverse electrodialysis process. The results indicate that adding roughness in the CNT duct increased the force between the primary fluid and the duct. Using an armchair-edged CNT structure maximized the electric current in the sample. Furthermore, the roughness increased the intensity of force in the channel, which was due to gravity, leading to a decrease in the mobility of fluid particles. Additionally, several broken hydrogen bonds inside the simulation box increased from 116 to 128 in the duct sample with roughness.

Production of Anthocyanin-Enriched Juices by Electrodialysis with Filtration Membrane Process: The Influence of Duration on Juice Composition, Process Efficiency, and Membrane Fouling.

The Electrodialysis with Filtration Membrane (EDFM) system has shown promise in juice enrichment, but further optimization is needed. This study evaluated the effect of processing duration (3 and 6 h) on juice composition, process efficiency, and membrane fouling. Results demonstrated a significant impact of processing time on juice composition, especially anthocyanin and mineral content. Two anthocyanin-depleted juices (-18.94% and -30.70%) and two anthocyanin-enriched juices (26.21% and 44.21%) were produced. Similar energy (1512.13 Wh/g of anthocyanins) was required to migrate equivalent amounts of anthocyanins over both time periods, with no impediment due to fouling observed, although the system's resistance increased (2.5-fold after 3 h, 3.2-fold after 6 h). Membrane fouling was characterized through conductivity, thickness, ATR-FTIR, SEM-EDX, and foulant identification. Minimal anthocyanin accumulation occurred on cation-exchange membranes (CEM), while anthocyanins and PACs concentrated within the filtering layer of filtration membranes (FM). However, fouling did not increase with longer processing. Structural alterations were noted in anion-exchange membranes (AEMs), suggesting instability under high electric fields. Overall, EDFM effectively enriched cranberry juice with anthocyanins, but further research is necessary to address AEM degradation under limiting current density conditions.

Kinetic control aspects and mechanisms in oriented membrane processes for extraction and recovery of ascorbic acid compound.

Ascorbic acid comprises four enantiomers, with only one of them, L-ascorbic acid, recognized as vitamin C. The modern industries place significant importance on obtaining this compound in its purest form. The challenge is to recover L-ascorbic acid, which requires specific processes within these industries. To satisfy this condition, purification is needed, a process that requires large quantities of solvents and high energy consumption. To overcome these limitations, we conducted a study on the facilitated extraction of L-ascorbic acid using three affinity polymer membranes, including supported liquid membrane (SLM), polymer inclusion membrane (PIM), and grafted polymer membranes (GPM) with cholic acid as the extractive agent. Following the characterization of the membranes using IR spectroscopy and SEM techniques, we investigated various parameters associated with substrate diffusion through the organic membrane phase. Regarding the biologically active L-ascorbic acid, our research findings indicated that kinetic factors drove the mechanisms of the studied processes.

Wastewater desalination for irrigation in inland regions

ABSTRACT Desalination using membrane processes is increasingly being implemented in coastal regions of the world to meet the water needs of the growing population. The use of this water treatment option to meet the growing water needs in inland regions, however, is impeded by the cost and regulatory challenges associated with responsible disposal of the concentrate brine. For inland regions of Australia, the use of evaporation ponds (EPs) is the only available brine management option. The high cost associated with construction and the high land requirements for EPs necessitates low waste brine volume production. This desktop study investigated the feasibility of achieving very high water recoveries and very low waste brine volumes in the reverse osmosis desalination of municipal wastewater for irrigation of crops near the inland town of Horsham, Victoria, Australia. Interstage lime and soda ash softening was selected as the means of removal of the scalants that prevent the achievement of high water recovery. It is hoped that this study will provide valuable information to aid in the planning of water reclamation operations for agricultural applications in inland areas at a time of increasing demand for water for food production and forecasts of population growth and climate change.

Efficiency of Optimized Fabrication Process for Light-absorbing Membranes from Sewage Sludge Applied in Solar-driven Steam Generation Systems

Solar-driven evaporation systems have been studied to provide clean water, especially for islandic areas. Carbon materials made from sludge in domestic wastewater treatment plants have been studied to produce light-absorbing membranes in solar-to-steam (STS) systems. However, the technical limitation of this method is that the water evaporation rate is still low. In this study, the process of manufacturing light-absorbing membranes was optimized to simplify the process while increasing the water evaporation rate and testing the application of converting seawater into fresh water. The optimal evaporation rate was 2.65 kg.m-2.h-1, higher than the system using vacuum drying membranes (1.88 kg.m-2.h-1) under 0.6 kW/m2 illumination conditions. When illuminated, the surface temperature of the TN_0.1 light-absorbing membrane reached 36.5°C, meaning 2.5°C higher than that of the reference membrane (without carbon material). The results of analyzing some anion and cation indicators in the harvested water showed that the fabricated STS systems could be applied well to convert seawater into fresh water for domestic use. Especially, the treatment efficiencies for , , , reach 99.87%, 94.35%, 99.5%, 99.98%, and 99.44%, respectively.

Fabrication of Robust Forward Osmosis Membrane by Assembling FeOxCly Nanoparticles

AbstractOwing to its inherent advantages like low‐energy consumption, low‐fouling propensity, and high recovering ability over high‐pressure‐driven membrane processes, the future of membrane technology is shifting toward forward osmosis (FO). However, the utility of FO in challenging areas is hindered by the lack of suitable FO membranes. Here, the development of innovative FO membranes by depositing weakly magnetic and positively charged FeOxCly nanoparticles on a negatively charged nylon membrane (FeOx‐Nyl) is reported. Remarkably, the FeOx‐Nyl membrane possesses outstanding stability in an aqueous medium and survived in both acidic (pH = 3.3) and basic (pH = 12.2) solutions. Upon varying the loading amount of FeOxCly, the water flux of the FeOx‐Nyl membrane varies from 27.8 to 61.3 LMH (from 5 to 30 mg). Due to its hydrophilic nature, the FeOx‐Nyl membrane exhibits excellent flux recovery rates (FRR), up to ≈70%. The outstanding robustness and high flux of FeOx‐Nyl are exploited in challenging applications like recovering reactive chemical wastes and dehydration of acetic acid.

Design of a bifunctional prepolymer for simultaneously facile preparation and highly efficient electrodialysis of anion exchange membranes

A facile fabrication process for separation membranes is crucial to decrease the production cost, while the photo-polymerization approach can be conducted at ambient conditions with short processing time and low energy consumption. Herein, this work designs a bifunctional prepolymer for simultaneously facile preparation and highly efficient electrodialysis of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) anion exchange membranes. PPO is selected as the main skeleton of prepolymer because of the excellent mechanical and thermal stability. The dimethylaminoethyl methacrylate (DMAEMA) is grafted with brominated PPO by quaternization, where it contains cationic groups, i.e. quaternary ammonium, and photopolymerized groups, i.e. methacrylate C = C. This resulting prepolymer can be fast polymerized under UV irradiation via C = C from DMAEMA. This structure is synergistically regulated by the amounts of crosslinker DMAEMA and modifier N-bromosuccinimide. The optimized membrane exhibits an excellent ion exchange capacity of 2.19 mmol g−1, a water uptake of 38.17 %, and a tensile strength of 4.8 MPa. Meanwhile, its electrolyzer cell performance achieves a density of 580 mA cm−2 at an adjusted voltage of 2.1 V, and the desalination rate of seawater during electrodialysis reaches 98.34 %. This work provides a universal and facile fabrication route for high-performance AEMs.

Is Podocytopathy Associated with Gross Hematuria after COVID-19 Vaccination in Patients with Immunoglobulin A Nephropathy?

We experienced three cases of a fever and subsequent severe, prolonged gross hematuria after COVID-19 vaccination. A kidney biopsy revealed immunoglobulin A (IgA) nephropathy, and electron microscopy showed two types of podocytopathy (podocyte damage): loss of foot processes from the glomerular basement membrane and foot process effacement. Mesangial interposition was also present in cases 1 and 3 but not in case 2. Podocytopathy is known to be a cause of proteinuria; however, the reactions to COVID-19 vaccination described here suggest that it may also be related to hematuria in IgA nephropathy.

Techno-Economic Analysis of a Carbon Molecular Sieve-Based Xylene Isomer Purification Process.

The separation and purification of xylene isomers is critical to the production of polyethylene terephthalate (PET). These separations are complex to operate and demand tremendous amounts of energy and thus are an opportunity for reducing industrial energy consumption. Membranes provide a low-energy footprint technology with simpler operation, and recently, membrane materials have been developed that are capable of separating xylene isomers. While these materials have demonstrated the ability to separate xylenes, they have yet to be commercially deployed. This work conducts a techno-economic analysis (TEA) to provide insight on the commercial attractiveness of a p-xylene selective carbon molecular sieve (CMS) membrane from both a cost and energy standpoint. This TEA was conducted through the pairing of a Maxwell-Stefan transport framework for rigid microporous materials with process modeling. Single-stage organic solvent reverse osmosis (OSRO) and pervaporation processes were used to evaluate the effects of recovery, selectivity, and diffusivity on the energy intensity and cost of the xylene separation. The final analysis used two systems, a single pervaporation stage followed by two OSRO stages, which was compared against a three-stage OSRO cascade. These were benchmarked against the commercial Parex process. We estimate that the membrane processes have the potential to enable impressive cost savings compared to the Parex process. While both systems outperformed the Parex process in terms of cost, the pervaporation/OSRO hybrid process was able to achieve the lowest cost of all due to its reduced membrane surface area compared to standalone OSRO. These findings demonstrate the potential of membrane systems in the field of difficult small molecule solvent separations.

Application of non-acid stripping solution in hydrophobic membrane process for high-purity ammonia recovery from high-strength ammonium wastewater

Recently, resource recovery from wastewater has been in the spotlight due to climate change and the energy crisis. Ammonia has significant value as a resource that serves as fertilizer or eco-friendly fuel, with a market value ranging from $0.4 to $1.0 per kg-N. In the membrane contactor (MC) process, an acid stripping solution such as H2SO4 is generally used for high ammonia recovery efficiency. However, the ammonia-recovered stripping solution often has limited applications as fertilizer due to the presence of anions, necessitating costly downstream processes like electrochemical treatments to separate ammonia from these contaminants. This study introduces a novel approach that dynamically compares various stripping solutions to reduce chemical consumption while achieving high-purity ammonia recovery. Notably, the recovered ammonia from the membrane contactor showed no detectable levels of nitrate, other ions, or organic carbon, all without the use of acidic solutions. Furthermore, the benefit-cost ratio of 1.42, derived from the dynamic comparison, highlights the cost-effectiveness and demonstrates the practicality of this method compared to traditional acidic stripping approaches.This innovative comparison underscores the membrane contactor system’s ability to recover high-purity ammonia, presenting a sustainable and economically viable solution for ammonia recovery in wastewater treatment. It achieves this without the need for additional chemical agents or expensive downstream processes, offering a more efficient alternative to conventional methods.

Temperature dependence of water and salt transport in concentration gradient batteries: Insight from membrane properties

The performance of concentration gradient batteries (CGBs) based on reverse electrodialysis technology is inevitably influenced by seasonal temperature fluctuations; however, these effects have not been thoroughly investigated. This study explored the temperature dependence of water and salt transport in CGBs using five different membranes over a temperature range of 5–45 °C to elucidate these impacts. The results indicated that the temperature dependence of current efficiency and voltage efficiency in CGBs was respectively controlled by permeation processes (including both water and salt) and membrane resistance. The temperature dependence of mass transfer in these membranes was associated with the characteristics of the species crossing the membrane (such as size) and, more significantly, with membrane properties, including water volume fraction and fixed charge density. Therefore, we proposed that controlling these membrane characteristics can modulate the influence of temperature on mass transfer and CGB performance. This research enhanced our understanding of how temperature affects mass transfer mechanisms in different membranes and provided valuable insights for improving energy conversion in CGBs and other membrane processes.