From composition to performance: Evaluating the effect of emulsion liquid membrane components on lead removal from water.

Probing selective pollutant removal in nanofiltration processes: Critical insights from separation factor and removal difference.

Virus filtration is a critical step to ensure the safety of antibody-based therapeutics. Due to the stringent performance requirements, commercially available virus filtration membranes are limited, and studies on virus retention behavior across different antibodies remain scarce, partly due to the high cost of these biologics. Herein, we comprehensively evaluated a newly developed virus filtration membrane, UF-Viremoval-Plus, by benchmarking it against leading commercial virus filters. The results demonstrate that UF-Viremoval-Plus exhibits superior antifouling properties and virus retention performance, which are attributed to its less negative charge, higher hydrophilicity, gradient pore structure and funnel-shaped geometry. We further investigated the effects of key process parameters, including pH, ionic strength, antibody type, and concentration, on membrane flux and virus removal efficiency. The membrane maintained stable operation under varying pressures and process disturbances, consistently achieving virus removal levels above 4 log reduction value, with no evidence of virus breakthrough. However, significant shifts in feed solution pH or ionic strength, as well as membrane fouling caused by high protein concentrations, affected virus removal. These observations are governed by complex membrane-protein-virus interactions. This work provides theoretical insights for the rational design of virus filtration membrane microstructures and the optimization of viral clearance processes in biopharmaceutical manufacturing.

Ammonia (NH 3 ) has gained attention as a potential hydrogen carrier for its high hydrogen content and absence of carbon atoms. However, the main route for ammonia production is still the energy intensive Haber-Bosch process. In this study, the membrane reactor technology is proposed as an alternative to integrate ammonia synthesis reaction and its simultaneous separation within a single unit. A non-isothermal 1-D packed bed membrane reactor model was developed, in which ammonia synthesis is promoted by a ruthenium-based catalyst, and its in situ separation takes place by means of NH 3 -selective membranes. The mathematical model was first validated with experimental data in a packed bed reactor, and afterward used to study the feasibility of a packed bed membrane reactor, aiming to identify the optimal membrane performance required to enhance the reactor efficiency, in terms of H 2 conversion, NH 3 purity and NH 3 recovery. Initial results under isothermal conditions, demonstrate that a P N H 3 > 10 − 7 m o l P a − 1 m − 2 s − 1 and S N H 3 / H 2 = 50 are required to significantly boost H 2 conversion. On the other hand a S N H 3 / N 2 = 100 was selected as a trade-off value influencing NH 3 purity and NH 3 recovery. The operating conditions study revealed that both sweep gas-to-feed flow ratio and pressure difference across the membrane are crucial for enhancing reactor performance, with optimal conditions identified at SW = 6 and ΔP = 20 bar. Furthermore, in the adiabatic case study, the investigation of the heat exchange integration between feed gas and sweep gas streams, highlights the importance of the latter as cooling fluid, achieving the best results at inlet permeate temperature of 200 °C. This enabled to achieve an H 2 conversion of 93 %, along with NH 3 recovery and purity of 99.14 % and 5.65 % respectively. Hence, the mathematical model demonstrates that an adiabatic packed bed membrane reactor with the integration of heat exchange has the potential to attain greater H 2 conversion compared to the equilibrium constraint observed in a conventional packed bed reactor. • The current study investigated the impact of a membrane-enhanced process on ammonia production. • The results demonstrated a substantial enhancement in H 2 conversion in the membrane reactor. • NH 3 selectivity of 50 towards H 2 and 100 towards N 2 , are required as optimal membrane properties.

Microalgae technology has the potential to take part to the transition from traditional wastewater treatment plants (WWTPs) toward innovative water resource recovery facilities. However, microalgae separation and concentration from treated wastewater (WW) is currently a major limitation because of energy costs. In this study, we compared microalgae (Chlorella vulgaris) concentration using two low-energy membrane processes, i.e., microfiltration (MF) and forward osmosis (FO) under two configurations, i.e., submerged and cross-flow membrane systems. The impact of turbulences promoters such as aeration in submerged operation and the impact of spacers in cross-flow mode were assessed; filtration cell orientation was also evaluated. All systems allowed for four times volumetric concentration of the microalgae batches, but the lack of turbulence promoters substantially impacted permeation flux and efficient microalgae recovery. The preferred configuration is submerged operation with aeration allowing for more than 90% microalgae recovery both using MF and FO membranes. The main limitation of FO is the high salinity of the concentrated microalgae batch that may alter downstream treatment. Despite higher initial flux observed in cross-flow filtration, severe flux decreases and important microalgae biomass losses on membrane surface or within spaced-filled channel did not allow for faster concentration and with recovery limited to 77%. These results demonstrate the importance of membrane configuration for efficient microalgae harvesting and recovery offering key insights toward industrial-scale algae production. Furthermore, it suggests the potential for integrating a membrane system into photo-bioreactors for simultaneous microalgae cultivation and concentration.

Various factors need to be considered in process design optimization to implement the complex processes of CO2 capture, utilization, and storage (CCUS). Here, bi-objective optimization of single-stage CO2 membrane separation was performed for two evaluation indexes: cost and CO2 emissions. During optimization, the process flow configuration was fixed, the membrane performance was set under the condition of the Robeson upper bound, and the membrane area and operating conditions were set as variables. Bi-objective optimization was performed using an original algorithm that combines the adaptive design of experiments, machine learning, a genetic algorithm, and Bayesian optimization. Five case studies with different product CO2 purities in the constraint were analyzed. Pareto solutions were superior for case studies with lower product CO2 purities. The set of Pareto solutions revealed opposite directions for optimization: either (1) increase the membrane area to reduce CO2 emissions but increase costs or (2) increase power consumption and reduce costs but increase CO2 emissions. The implemented bi-objective optimization approach is promising for evaluating the membrane CO2 capture process and the individual processes of CCUS.

Rare are the people who, upon a first meeting, etch an indelible mark upon your mind. Professor Normal Epstein was such a person. I had the privilege of first meeting him relatively late in my career, during one of the annual receptions of The Canadian Journal of Chemical Engineering (CJCE). As a former Editor-in-Chief of the CJCE (from January 1985 to December 1989), Prof. Epstein made it a point to attend the CJCE receptions during the yearly CSChE conferences all the way up into his nineties. I remember the pleasant conversations we had during these meetings, as well as the invaluable pieces of advice he gave me on how to manage the CJCE. (Talk about large shoes to fill!) He was also a regular reviewer of papers for our Journal. And what reviews they were: scientifically accurate, meticulous, respectful of the authors' ideas but not afraid of pointing out the weak points in their reasoning, and written in an elegant style that is now lost to most of us—in longhand! Prof. Epstein passed away on 29 July 2023—short of his 100th birthday—after a long and distinguished career in the Department of Chemical and Biological Engineering at the University of British Columbia. He was an outstanding chemical engineer, lecturer, mentor, and an inspiring leader in the areas of spouted beds, heat exchanger fouling, liquid–solid and three-phase fluidization, and dynamic particulate processes. Perhaps more importantly, he was a remarkable colleague, friend, and a true gentleman. It is, therefore, a great honour to write this preface introducing the special section of the CJCE dedicated to his many accomplishments. The 12 articles included herein cover many of the areas in which Prof. Epstein excelled and includes authors from across the globe, gathered together here to celebrate a life dedicated to chemical engineering science. ‘It is uniquely our choice as to how we look at the world, once we escape the formalisms of training and psychological inertia of our own consciousness. Looking at things from a new direction, interpreting the world in a different light is considered WISE, and accepting the perspectives of others is more precious than ever. Finding time and space for all in the discussion of science is the utmost priority, and our community of practice would benefit from change’. ‘We can consider how to fractionate the above teetering problem into subsystems, increasing complexity as we provide discrete connections in unit sub-shells, accommodating quantum and chaotic principles; however, we often lose sight of the larger microcosm of long-range interaction: Why we practice these technologies, and how we can work together for the better world that Norman dreamt of for nearly a century’. In a timely literature review, Jankovic and Wilkinson[10] explore the transition to electrochemical processes in clean energy technologies, with emphasis on hydrogen-containing fuels. Along similar lines, Bi et al.[11] discuss ammonium crossover as a function of membrane type and operating conditions in electrochemical flow cells for ammonia synthesis and water treatment applications. Finally, Qu et al.[12] close Prof. Epstein's special section with the relevant topic of biomass utilization, presenting a detailed kinetic study of microwave pyrolysis of sewage sludge and corn stalk mixture. I would like to thank all the authors who joined us in celebration of the remarkable career of our dear colleague and friend, Norman Epstein. Making mine the words of David R. Bruce, let's strive to ‘work together for the better world that Norman dreamt of for nearly a century’. I hope our readers will enjoy reading these articles as much as I did. João B. P. Soares: Conceptualization; writing – original draft. The peer review history for this article is available at https://www.webofscience.com/api/gateway/wos/peer-review/10.1002/cjce.25599.

Membrane life and performance are crucial factors in adopting membrane-based processes for water treatment and separations. This study investigated various time series models using hold-out validation of experimentally generated water vapor flux and salt rejection rates. Membrane properties were optimized by incorporating carbon-based nanomaterials to enhance anti-wetting and porosity, developing correlations between membrane characteristics and high fluxes. Fine-tuned Autoregressive Integrated Moving Average (ARIMA), Prophet, Exponential Smoothing, and Neural Prophet models were trained on an experimental dataset (N=434) collected over 36 hours to forecast performance for 72 hours. Results demonstrate the superiority of the Exponential Smoothing statistical model in predicting and forecasting membrane performance, yielding the lowest root mean square error (RMSE) of 0.006 and mean absolute error (MAE) of 0.007. This outperformance is attributed to its non-linear data fitting approach, which employs weighted averages to mitigate non-stationary behavior in time series data, a characteristic often observed in membrane performance over time. While other models showed promise, they did not match the accuracy of Exponential Smoothing in this context. The proposed modeling approach offers a more efficient alternative to traditional experimental studies, potentially leading to significant cost and time savings in the research and development phase of membrane distillation processes. This method's applicability to various membrane types and operational conditions warrants further investigation.

This work characterized different cation- and anion-exchange membranes to improve the efficiency for the electrochemical conversion of Li2SO4 into LiOH and simultaneously recover H2SO4 as a byproduct, an essential process for sustainable alternatives for lithium−ion battery recycling. The membrane’s ability to block H+ and OH− migration over the membrane to the feed stream of the electrolyzer was investigated. Simultaneously, the membrane resistance was measured to assess its impact on the cell voltage and overall energy consumption. The best CEM, Sx-2301-Wn, enabled to concentrate LiOH up to 1.7M with a current efficiency (CE) of 77.3%, while Fumasep FAB-130-PK, the best AEM, was able to concentrate H2SO4 up to 0.6M with a CE of 74.6%. The recirculation of LiOH into the middle compartment to maintain a constant pH was also investigated and showed to improve both Li+ (4.2%–8%) and SO42- (5.1%) migration, but pH higher than 3 led to an increased membrane resistance. The results of this work contributed to the selection of a suited membrane and ideal operational conditions for producing LiOH and H2SO4 through a three-compartment membrane electrolysis cell.

Open and FAIR data for nanofiltration in organic media: A unified approach

Abstract Electrochemical flow cells are promising designs for both ammonium () electrosynthesis from dinitrogen and removal/recovery from wastewater. The crossover is undesirable for electrosynthesis but is favourable for removal. The crossover is investigated herein under different current densities, concentrations, and feed locations using cation‐exchange (Nafion N112, N350) and anion‐exchange (Sustainion X37‐50) membranes and microporous diaphragms (Celgard 3400, 3500, and 5550). For Nafion N112, the crossover from catholyte to anolyte decreases with higher concentrations from 81.9 ± 4.7% at 1 ppm to 10.7 ± 0.7% at 3400 ppm. At a constant concentration, increasing the current density leads to more intense electrolyte pH polarization, which leads to volatilization in favour of recovery up to 78.1 ± 1.1% at a cathode superficial current density of −10 A m−2. When comparing the recovery efficiency, the cathode‐ and symmetric fed operations were outperformed by the anode‐fed mode for 3400 ppm due to the equilibrium that buffers the pH change. For Celgard diaphragms, modest crossover (<5%) was only demonstrated at low current densities (≤−1 A m−2), but the separation was compromised by the bulk electrolyte transport through micropores and electrolysis‐induced pH polarization, highlighting future needs to develop and rigorously verify separators toward electrosynthesis.

Hydrogen powered proton exchange membrane fuel cells (PEMFC) have great potentials to replace the traditional internal combustion engines due to its inherent advantages of zero greenhouse gas emissions, better fuel efficiency, quick startup, silent operation, less required maintenance, etc. In a PEMFC, oxygen transport is a critical performance limiting factor because of the sluggish oxygen reduction reaction kinetics. Limiting current method is a well-established in-situ diagnostic tool to measure the oxygen transport resistance in a PEMFC. To obtain accurate oxygen transport resistances, a few key assumptions need to be made including: (1) the effect of temperature gradient in the diffusion media is negligible, (2) no convective flow in the porous media, (3) oxygen is diluted in a gas mixture of nitrogen and water vapor, (4) the total oxygen transport resistance combines gas diffusion layer, microporous layer, and catalyst layer, (5) the effect of membrane thickness has negligible effect, and (6) the anode side does not affect the measurement results due to fast hydrogen oxidation reaction. In this study, we perform a systematic study of the effect of membrane thickness and operating conditions on obtaining robust and reliable limiting current measurement. Standard Nafion membranes of three different thicknesses (25, 50, and 85 µm) are tested with Toray 060 and Freudenberg H23C8 diffusion media. In addition, we further study the interaction between membrane thickness and asymmetric pressure and relative humidity and their effects on limiting current results. Our results show that membrane thickness and relative humidity are critical factors in obtaining reliable oxygen transport resistance due to their effect on overall water balance in the cell. Lastly, the experimental data are compared with the simulation results to establish fundamental understanding. Detailed experimental and analytical results will be presented at the conference.

Multi-output machine learning for addressing the trade-off between water permeability and wetting resistance in membrane distillation

Multi-objective optimization of comprehensive performance enhancement for proton exchange membrane fuel cell based on machine learning

Affordable thin-film composite (TFC) membranes are a potential alternative to more expensive ion exchange membranes in saltwater electrolyzers used for hydrogen gas production. We used a solution-friction transport model to study how the induced potential gradient controls ion transport across the polyamide (PA) active layer and support layers of TFC membranes during electrolysis. The set of parameters was simplified by assigning the same size-related partition and friction coefficients for all salt ions through the membrane active layer. The model was fit to experimental ion transport data from saltwater electrolysis with 600 mM electrolytes at a current density of 10 mA cm-2. When the electrolyte concentration and current density were increased, the transport of major charge carriers was successfully predicted by the model. Ion transport calculated using the model only minimally changed when the negative active layer charge density was varied from 0 to 600 mM, indicating active layer charge was not largely responsible for controlling ion crossover during electrolysis. Based on model simulations, a sharp pH gradient was predicted to occur within the supporting layer of the membrane. These results can help guide membrane design and operation conditions in water electrolyzers using TFC membranes.

Pineapple (Ananas comosus L., Merril) and pomegranate (Punica granatum L., Punicaceae) are the most popular tropical non-citrus fruits, mainly because of their attractive aroma, refreshing flavour and favourable brix/acid ratio. The research was carried out on the biochemical analysis of membrane clarified pomegranate and pineapple juices. Membrane clarified permeates of both the juices were collected and the biochemical analysis was conducted. Among the MF membranes 0.1 µm membrane operated at 15 psi (1.0342 bar) TMP and 30 Lph flow rate gave higher flux and permeate of improved biochemical properties for pomegranate juice. In UF of pomegranate juice, in the order of permeates that recorded higher flux and improved biochemical properties were at membrane operating conditions 70 kDa, 15 psi (1.0342 bar) and 30 Lph; 44 kDa, 15 psi (1.0342 bar) and 40 Lph and 10 kDa, 15 psi (1.0342 bar) and 40 Lph. Similarly, the pineapple juice also recorded higher permeate flux and improved biochemical properties during both MF and UF when operated at 0.1 µm, 15 psi (1.0342 bar) and 30 Lph; 70 kDa, 15 psi (1.0342 bar) and 30 Lph and 44 kDa, 15 psi (1.0342 bar) and 40 Lph. It can be concluded that both MF and UF can be used to clarify juices, but UF appears to be better than MF.

Hydrogen fuel cells (FCs) are key energy devices that can accelerate our transition away from non-renewable, carbon-intensive fuels especially in the grid-scale storage and transportation sectors. FC cathodes perform the oxygen reduction reaction (ORR), and despite decades of progress towards higher performance electrocatalysts, the ORR remains kinetically sluggish and limits the efficiency of assembled FC devices. Modern, commercially available FC cathodes typically contain platinum (Pt)-based catalysts that can cause the overall FC to become prohibitively expensive for some applications so identifying alternate non-platinum group ORR catalyst formulations could increase deployment of FCs. Physics-based calculations with density functional theory (DFT) have predicted many first-row transition metal oxides (MOx, M = Mn, Fe, Cr, Ni, Co) as having favorable ORR performance trends. Additionally, there is experimental validation of nanoscale ternary and quaternary transition metal oxide systems with a mixture of transition metals used for catalyzing the ORR where relatively modest activity enhancements are reported. Despite this progress, an important limitation is present in the low material stability of non-precious transition metal oxides especially in acidic environments such as those encountered in proton exchange membrane FCs. Using synthetic material strategies to overcome such stability limitations in a variety of FC operating conditions will provide a deeper understanding of the relationship between structure, activity, and degradation.In this work, we employ two simultaneous strategies to work towards enhancing the activity and stability of transition metal oxides: (1) addition of antimony (Sb) as a ligand and (2) functionalization with nitrogen or sulfur. We utilized a previously reported colloidal synthesis for uniform ~ 50 nm oxide nanoparticles for manganese, nickel, cobalt, and iron to produce four sets of nanoparticles based on each of these metals. By using a colloidal synthesis that concurrently introduces Sb with the secondary metal and drying the particles afterwards, we incorporate Sb evenly throughout the polycrystalline structure of the of these nanoparticle catalysts. A high temperature surface modification reaction with reactive gas such as air, ammonia, or hydrogen sulfide was used to convert any remaining transition metal antimonate into an oxide, nitride, or sulfide, respectively. In total, twelve materials are used in this study: the oxide, nitride, and sulfide (collectively “X-ides”) of each of the four transition metal containing, antimony incorporated nanoparticles. We optimize this material synthesis and evaluate the nanoparticle catalyst’s ability to enhance electrochemical ORR activity in both acidic (pH 1) and alkaline (pH 13) conditions which are simulating operating conditions of proton-exchange membrane and anion-exchange membrane FCs, respectively. In addition to activity modulation, we measure the ORR selectivity change towards hydrogen peroxide formation for each material and note the role of nitrogen and sulfur modification in suppressing hydrogen peroxide formation in alkaline environments. In addition to electrochemical characterization, we employed a vast array of bulk and surface characterization techniques to understand catalyst dynamics and contextualize observed activity trends. Transmission electron microscopy (TEM) enabled determination of particle sizes and morphologies alongside electron diffraction patterns to validate the catalyst synthesis. X-ray diffraction (XRD) then provided further information about crystallinity that connected bulk-level insights to the local information from TEM. X-ray photoelectron spectroscopy (XPS) enabled determination of oxidation state changes in the transition metal and in Sb that serve as important descriptors for estimating the activity of these catalysts. We also employed in situ/operando techniques to probe catalyst dynamics and stability under various conditions. Using manganese K-edge synchrotron x-ray absorption spectroscopy (XAS) on the manganese antimony X-ides, we find significant changes to oxidation state and coordination of manganese in the nitride and sulfide as a function of potential indicating processes that displace nitrogen and sulfur in the lattice under certain conditions. Lastly, we use an in situ electrochemical flow cell coupled to inductively coupled plasma-mass spectrometry (ICP-MS) to measure corrosion as a function of ORR current density, potential sweeping, and electrolyte gas saturation to determine degradation patterns. Insights from all these techniques provide a fascinating perspective on what factors in a material and its environment are responsible for enhanced activity, selectivity, and stability. We perform DFT modeling of these systems to further elucidate material properties that are principally responsible for achieving key metrics in activity and stability especially as non-precious catalysts are evaluated for their performance in assembled device conditions. Combining electrochemical experiments, physics-based modeling, and material characterization to better understand structure-performance relationships is a promising path towards accelerating the process of materials discovery for eventual deployment in critical energy applications for the future.

Two membrane systems were proposed as novel spherical agglomeration techniques. The first system uses a flat static membrane with different pore sizes and different pore configurations, while the second system is based on an oscillating cylindrical membrane. The main objective is to enhance the control of the bridging liquid droplet size and generate a large density of monodisperse droplets, which, in turn, allows better control and tuning of the properties of the spherical agglomerates. Spherical agglomerates of benzoic acid were obtained under different conditions, namely, the agitation rate, the bridging liquid flow rates and total addition time, and membrane properties. Spherical agglomeration was successfully achieved by using the proposed membrane configuration and operating conditions. It was shown that the flat membranes, particularly the ring membrane, provide enhanced control over the bridging liquid droplet size, which resulted in a more effective control of the size, morphology, and micrometric properties of the spherical agglomerates. Most importantly, with the proposed systems, it was possible to significantly reduce the bridging liquid to solid ratio (BLSR) down to 0.3–0.7 mL/g compared to the values commonly reported in the standard procedure (i.e., 0.59 to 1.25 mL/g).

Covalent codeposition modification of reverse osmosis membranes with Noria and zwitterionic copolymers for antifouling in reclaimed water production

Superior performance of a membrane bioreactor through innovative in-situ aeration and structural optimization using computational fluid dynamics.