Flat Sheet Membranes Research Articles

Integrated membranes system for water application in microbiology/molecular biology

An integrated membrane filtration system was developed to make water purity suitable for microbiology/molecular biology research. Water samples were collected from outlets in different buildings of the National Research Center and analyzed for their composition before filtration. An integrated membrane system was developed based on mathematical modeling. Flat sheet membranes were produced, including microfiltration, ultrafiltration, and nanofiltration membranes. The flat sheet membranes were converted to a spiral wound module filter to simulate the local market filters and applied in the integrated membrane system that was designed and installed. The produced water was analyzed and compared to molecular-grade water used in different molecular biology/microbiology applications. Both PCR, agarose gel electrophoresis, bacterial liquid cultures, and viral propagation indicated that treated water using the herein-developed system exhibited comparable performance to the molecular grade water provided with imported reagent kits. So, this research can offer a promising solution for producing high-quality water suitable for sensitive laboratory applications.

Synthesis, characterization, and performance of MXene-Modified PVC Membranes for organic and inorganic separation

This study explores the transformation of polyvinyl chloride (PVC) flat sheet membranes for the first time using MXene, a hydrophilic two-dimensional (2D) nanosheet, to enhance ultrafiltration (UF) performance for wastewater treatment. The loading of MXene in the PVC solution was adjusted from 0 to 0.5g in order to create modified membranes. The properties and performance of these membranes were thoroughly analyzed using field emission scanning electronmicroscopy (FESEM), contact angle (CA) measurements, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), water permeation flux, Bovine serum albumin (BSA) rejection, and Pb metal ions removal tests. Among the developed membranes, the N2-modified PVC membrane, with 0.4g of MXene, exhibited the most favorable characteristics, including a contact angle of 65.77° and a porosity of 84.8%. This membrane achieved the highest clean water permeation flux of 201.3 LMH, along with a 99.9%, 91.03% BSA and Pb metal ions rejection rate respectively, and a flux recovery ratio (FRR) of 90.2%. The incorporation of MXene nanosheets significantly enhanced membrane efficiency compared to neat PVC membranes, demonstrating the promising capabilities of MXene-modified PVC membranes for effective wastewater treatment.

Impact of polyimide on the recycling of waste expanded polystyrene into flat-sheet filtration membrane

Impact of polyimide on the recycling of waste expanded polystyrene into flat-sheet filtration membrane

Scaling and wetting resistant silica nanoparticle grafted multi-scale corrugated omniphobic membranes for membrane distillation

Membrane distillation (MD) is a promising technology for wastewater treatment, but often faces significant challenges of scaling and wetting. Development of advanced omniphobic membranes has been the core research for mitigating scaling and wetting in MD. In this study, a novel fluorinated multi-scale silicon nanoparticle grafted corrugated (FSiC-PVDF) membrane (water contact angle 179.5 ± 0.3°) was prepared and explored for enhancement of anti-scaling performance by calcium sulfate and anti-wetting performance by sodium dodecylsulfate (SDS). Silica nanoparticles (SiNPs) were synthesized and covalently bonded to the surface of the corrugated membrane and the surface energy was further reduced via chemical fluorination. Flat-sheet membrane (F-PVDF) and corrugated membrane (C-PVDF) were compared. Results showed that compared to the previous study of grafting SiNPs on flat membranes directly, FSiC-PVDF exhibited superior flux (21.1 kg/(m2·h)), and it can consistently demonstrate stable water flux and quality even at high calcium sulfate and SDS concentrations. The F-PVDF experienced significant declines in performance, and the C-PVDF showed limited improvement in scaling and wetting resistance. Corrugation pattern contributed to a larger evaporation area and higher velocity near the membrane surface, thus reducing crystal deposition and heterogeneous nucleation on the surface. The combination of corrugation and SiNPs resulted in a stable Cassie-Baxter wetting state, reduced solid-liquid interface areas, and created slippage conditions that minimized the impact of contaminants on MD performance. These findings indicated that FSiC-PVDF membranes offer significant advantages for MD processes, enhancing operational stability and efficiency.

Fabrication of TiO2@ZIF-67 metal organic framework composite incorporated PVDF membranes for the removal of hazardous reactive black 5 and Congo red dyes from contaminated water

Novel application of TiO2@ZIF-67 composite incorporated poly (vinylidene fluoride) (PVDF) mixed matrix flat-sheet membranes for treating the water contaminated with hazardous reactive black 5 and congored dyes was the crux of this work. The composite was characterized by FTIR, BET, XRD, zeta potential and particle size, and TGA. The as-synthesized composite was embedded in the PVDF polymeric matrix and flat-sheet-membranes were fabricated adopting the NIPS method followed by the different characterizations like scanning electron microscopy, EDS, elemental mapping, contact angle, atomic force microscopy, surface energy, and XPS. Results of the performance studies showed an enhanced pure water permeability from 150.99 Lm-2h−1 for neat membrane to 261.39 Lm-2h−1 for TZM-2. The reactive black 5 dye was rejected in 97.4 %, 92.2 %, and 84.84 % in acidic, basic and neutral conditions respectively by TZM-2 membrane. Whereas, the PVDF membranes without the composite showed rejections of 83.19 %, 82.5 %, and 72.1 % respectively in acidic, basic, and neutral conditions. The Congo Red dye was rejected in 89.4 %, 95.68 %, and 92.4 % in acidic, neutral and basic conditions respectively by TZM-2 membranes. Whereas, the PVDF membranes without the composite showed rejections of 82.8 %, 91.9 %, and 85.4 % respectively in acidic, neutral and basic conditions.

Extending the applicability of concentration polarization-enabled “click” hydrogel coating of desalination membranes

Reverse osmosis (RO) systems continually struggle with membrane fouling, leading to diminished membrane permeability and therefore elevated energy requirements. Building on prior own research, this study presents further development of an in situ antifouling coating technique for commercial RO flat sheet membranes and spiral-wound modules, deploying a concentration polarization-driven reactive (“click”) coating formation process. Utilizing this approach, zwitterionic (self-synthesized polyacrylates) and nonionic (functionalized “clickable” poly(vinyl alcohol)) coating materials were employed. Relying on comprehensive statistical analysis and the design of experiments (DOE) framework for lab-scale experiments, essential parameters that dictate the efficiency of the coating process were identified. By modulating the extent of concentration polarization, precise control over the permeance of modified membranes and spiral-wound modules was achieved. A robust correlation emerged between the relative permeance change (RPC) post-modification and the relative end permeance change (REPC) during modification. This correlation serves as basis for the real-time prediction and adjustment of final membrane performance, enabled by online flux monitoring during the modification and stopping it a preset REPC value—a relationship substantiated through extensive experiments on both lab-scale and pilot plant platforms. In performance comparisons, the modified membranes consistently surpassed unmodified variants in both selectivity and antifouling resilience. With successful upscaling to commercial TW30-2521 modules in a pilot plant setting, a significant step toward industrial readiness has been made. Overall, this work introduces a scalable, predictable, and controllable in situ coating method for RO membranes and modules that enables balancing enhanced anti-fouling functionality with preserved flux performance at uncompromised solute rejection.

Easy Fabrication of Ultrafiltration Membrane via Polyethersulfone-Fumed Silica

This study investigated the effect of low-concentration fumed silica (FS) in polyethersulfone (PES) membranes. The PES/FS blend membrane was fabricated using a wet phase inversion technique as a flat sheet membrane. Scanning electron microscopy analysis revealed improved pore connectivity and rounder middle structures due to the addition of fumed silica. The experimental results indicated that the fabricated membranes fell within the ultrafiltration range, with pure water flux increasing as fumed silica concentration rose. The pure water flux improved by 64% compared to the native PES membrane. Furthermore, the blend membranes exhibited better selectivity, rejecting pepsin and lysozyme 11% and 19% more efficiently, respectively. Although the low concentration of fumed silica had minimal impact on the water contact angles of the membrane surface, all membranes demonstrated hydrophilicity. This cost-effective approach enhances permeability while maintaining separation characteristics, making it suitable for clean water applications.

Poly(4-methyl-1-pentene)/ polypropylene alloy hollow fiber membrane with high rigidity for blood oxygenation

The oxygenator with hollow fiber membranes (HFMs) is the key component of the extracorporeal membrane oxygenation which allows the blood to be oxygenated and the carbon dioxide to be removed. The poly(4-methyl-1-pentene) (PMP) is recognized as the optimal oxygenated membrane material with high gas permeability coefficient, and the oxygenated membrane fabricated from it has an asymmetric structure that can resist plasma leakage for a long period of time. However, the relatively low rigidity of PMP oxygenated membrane makes it difficult to be processed in subsequent weaving and applications, during which deformation and fracture of HFMs often happen. In this work, the polymer alloy oxygenated membranes are fabricated by blending polypropylene (PP) as a high rigidity reinforcement agent with PMP via thermally induced phase separation (TIPS). Firstly, the effect of the PP content on phase separation structure and crystallization of alloy flat sheet membrane are investigated. When the PP content is 15 wt%, the rigidity of the alloy membrane reinforces dramatically. The elastic modulus and tensile strength of the PMP-PP-15 alloy membrane is 288.5 ± 12.4 MPa and 8.3 ± 0.4 MPa, respectively, which is 275.7 % and 96.7 % higher than that of the PMP membrane. Furthermore, PMP-PP-15 alloy HFM are fabricated under the optimum polymer composition. The elastic modulus of the PMP-PP-15 alloy HFM is 312.6 ± 16.0 MPa, which is 679.6 % higher than that of the PMP HFM and 40.1 % higher than that of the commercial PMP HFM. Meanwhile, the tensile strength and fracture stress are 15.4 ± 0.7 MPa and 186 ± 12.2 cN, respectively, which are both higher than those of the PMP and commercial PMP HFM. In addition, the PMP-PP-15 alloy HFM shows high gas permeability and oxygenation performance. This study might provide a convenient method to achieve rigidity reinforcement of PMP-based oxygenated membranes with great potential for application.

Dialysis nanocomposite membranes based on carbon nanoforms inhibiting blood plasma protein adsorption.

Protein adsorption on medical devices in contact with blood is a significant issue during renal replacement therapy. Main forces determining fouling are the electrostatic interactions between membrane and charged protein, but the dialysis membrane surface charges can be adjusted by modifying the polymer matrix to decrease the blood plasma protein adsorption. In this study, polysulfone membranes (PSU) were modified by incorporation of carbon nanoparticles such as: multiwall carbon nanotubes (2 wt.% MWCNT), graphene oxide (1 wt.% GO), and graphite (5 wt.% GR) during manufacturing process (nonsolvent-induced phase separation, NIPS). The PSU flat sheet membrane was the reference sample. Observed morphology of nanocomposite membranes was similar (SEM imaging); all of them had finger-like pore structure with unimodal distribution of pore size and similar skin-to-support ratio (1:3). The carbon nanoadditives also influenced the surface wettability: hydrophobicity and surface free energy of membranes increased (polar components of energy were reduced, while the dispersive components were increased). The surface charge of nanocomposite membranes increased, when the polymer matrix has been modified with CNT or GR. This significantly affects the adsorption of proteins such as chicken (CSA) and bovine serum albumin (BSA) and reduces blood clotting on the membrane.

Development of Hollow Fiber Membranes Functionalized with Ionic Liquids for Enhanced CO2 Separation.

The combination of CO2-selective ionic liquids (ILs) with block copolymers, such as Pebax 1657, has demonstrated an enhancement of the gas separation capabilities of polymeric membranes. In the current work, the development of composite membranes by applying a thin, concentrated selective layer made of Pebax/imidazolium-based ionic liquids (ILs) is presented. The objective of the experiments was to determine the optimized IL loading and investigate how the alteration of the anion impacts the properties of the membranes. Two membrane configurations have been studied: coated flat sheet membranes, supported on a porous poly(ether sulfone) (PES) layer, as well as composite hollow fiber membranes, supported on commercial polypropylene (PP) hollow fibers. Coated hollow fiber composites were fabricated using a continuous coating method, offering a straightforward scalability in the manufacturing process. The determined mechanical pressure stability of hollow fiber composites reached up to 5 bar, indicating their potential for various industrial gas separation applications. It was found that the Pebax 1657-based coating containing 40 wt % [C6mim][NTf2] yielded membranes with the best gas separation properties, for both the coated flat sheet and the hollow fiber configurations. The CO2 permeance of hollow fibers reached 23.29 GPU, whereas the CO2/N2 ideal selectivity stood at 8.7, suggesting the necessity of the further enhancement of the coating technique, which can be achieved, for example, through application of multiple coatings. Nonetheless, the superior ideal selectivity of the CO2/CO separation, reaching 12.44, gave a promising outlook for further novel membrane applications, which involve the separation of the aforementioned gases.

Composite flat-sheet membrane adsorbent of Li2TiO3-Ethylene-co-vinyl alcohol (LTO-EVAL) for lithium extraction

Composite bead adsorbents have been prevalent for the extraction of Li+ from brines. However, adsorbent beads generally demonstrate declining adsorption capacity and require extended equilibrium time when used repeatedly in absorption/desorption cycles. To overcome this challenge, a novel composite flat-sheet membrane adsorbent based on ethylene-co-vinyl alcohol (EVAL) and Li2TiO3 (LTO) is reported herein for highly efficient Li+ extraction from a geothermal brine. At an optimal LTO loading and membrane thickness, the resulting LTO-EVAL membrane was characterized by a large open macrovoid structure for fast ion transport, a fast adsorption rate that reached equilibrium in 0.5 h, and a high capacity of 96 % of that of the powder. The new membrane adsorbent showed adsorption behavior consistent with the Langmuir model and pseudo-second-order kinetic model. For a geothermal brine with a low lithium concentration, the LTO-EVAL membrane showed stable performance in 13 rapid adsorption/desorption cycles, with adsorption capacity at an average adsorption capacity of 7.3 mg/g and a 70 % adsorption efficiency. The average dissolution rate of Ti4+ was below 0.6 % in each cycle. The structure of the adsorbent material showed no discernable changes in chemical structure as confirmed by XRD and SEM results. With the improved extraction efficiency, the reusable membrane adsorbents would be economically viable in the long run and could potentially serve as the next generation of scalable Li+ adsorption material for brines. Further utilization of membrane adsorbent would lead to new design of adsorption modules and systems with reduced footprint. We need to further optimize the stability of the membrane adsorbents so that loss of Li2TiO3 remain at low level to reduce the lost for lithium extraction from the geothermal brine.

Performance and Environmental Assessment of Biochar-Based Membranes Synthesized from Traditional and Eco-Friendly Solvents.

Water contamination resulting from coal spills is one of the largest environmental problems affecting communities in the Appalachia Region of the United States. This coal slurry contains potentially toxic substances, such as hydrocarbons, heavy metals, and coal cleaning chemicals, and its leakage into water bodies (lakes, rivers, and aquifers) can lead to adverse health effects not only for freshwater bodies and plant life but also for humans. This study focused on two major experiments. The first experiment involved the use of biochar to create a biochar-polysulfone (BC-PSf) flat-sheet multifunctional membrane to remove organic contaminants, and the other major experiment compared eco-friendly (gamma-valerolactone-GVL; Rhodiasolv® PolarClean-PC) and petroleum-derived solvents (i.e., N-methyl-pyrrolidone-NMP) in the fabrication of the biochar-polysulfone membranes. The resulting membranes were tested for their efficiency in removing both positively and negatively charged organic contaminants from the collected water at varying pH values. A comparative life cycle assessment (LCA) with accompanying uncertainty and sensitivity analyses was carried out to understand the global environmental impacts of incorporating biochar, NMP, GVL, and PC in the synthesis of PSf/NMP, BC-PSf/NMP, PSf/GVL, BC-PSf/GVL, PSf/PC, and BC-PSf/PC membranes at a set surface area of 1000 m2. The results showed that the addition of biochar to the membrane matrix increased the surface area of the membranes and improved both their adsorptive and mechanical properties. The membranes with biochar incorporated in their matrix showed a higher potential for contaminant removal than those without biochar. The environmental impacts normalized to the BC-PSf/GVL membrane showed that the addition of biochar increased global warming impacts, eutrophication, and respiratory impacts by over 100% in all the membrane configurations with biochar. The environmental impacts were highly sensitive to biochar addition (Spearman's coefficient > 0.8). The BC/PSf membrane with Rhodiasolv® PolarClean had the lowest associated global environmental impacts among all the membranes with biochar. Ultimately, this study highlighted potential tradeoffs between functional performance and global environmental impacts regarding choices for membrane fabrication.

Synthesis of a novel polymer and design of carboxylate-terminated hyperbranched PEI-incorporated PVDF membranes for efficient oil-in-water emulsion separation

Polyvinylidene fluoride (PVDF) membranes utilizing ultrafiltration (UF) and microfiltration (MF) configurations have widely been used in many separation processes, including oil/water emulsions. Recently, there have been tremendous research interests in designing PVDF membranes on their structural-property relations as well as high separation performances. Herein we report the synthesis of a novel carboxylate-terminated hyperbranched polyethylenimine (CHPEI) using a facile three-step one-pot strategy to enhance the characteristics of PVDF membranes for oil/water emulsion separation. The first step involved the production of one amide and one carboxylate functional group per maleic anhydride molecule on the outer surface of polyethylenimine (PEI). The second step involved producing two additional carboxylate groups via amine-based Michael addition of alkenes using aspartic acid dimethyl ester hydrochloride, followed by basic hydrolysis. CHPEI-n-PVDF membranes having various CHPEI contents are further fabricated by a phase-inversion process, obtaining as free-stable flat-sheet membranes. The synthesized polymer and membranes were thoroughly characterized by FTIR and 1H NMR, SEM, EDX, mapping, AFM, and contact angle analysis. The incorporation of CHPEI into PVDF positively enhanced the hydrophilicity, and the WCA was significantly reduced from 80.6° to 59.5°. The maximum permeation flux was obtained using CHPEI-3-PVDF membranes, which was 200 % more than that obtained using pristine PVDF. The CHPEI-2-PVDF membranes exhibited a rejection performance of >99 % for separating oil-in-water emulsions. The incorporation of CHPEI into PVDF significantly improved the antifouling characteristics of the membranes. After 5 h of operation in separating oil-in-water emulsions, the flux recoveries of CHPEI-2-PVDF and CHPEI-3-PVDF were found to be 92 % and 97 %, respectively. CHPEI has demonstrated a considerable positive influence in improving the PVDF membrane’s performance, making it an excellent candidate for oily wastewater treatment because of its high rejection performance and excellent flux recovery ratio.

High-temperature reverse osmosis and molecular separation with robust polyamide-ceramic membranes

Polyamide thin-film composite (TFC) membranes are widely used for reverse osmosis (RO), but most commercial RO membranes have a limited operating temperature of <45 °C. This has constrained the broader applications of RO in industries, where process and water feeds with high temperature >50 °C are common. In this study, robust polyamide-ceramic TFC membranes were developed for high-temperature RO (HT-RO). RO-type polyamide thin-film was successfully synthesized on the inner surface of ceramic tubular membranes via interfacial polymerization. The polyamide-ceramic membranes exhibited excellent thermal stability, maintaining high NaCl rejection (>98 %) and steady water permeability (∼5 LMH/bar) during HT-RO at 70 °C. The molecular weight cut-off (MWCO) of the membranes increased slightly from 90 to 140 Da at 70 °C, and the surface charge played an important role in maintaining the high salt rejection. Long-term stability tests showed that polyamide thin-films may undergo thermal hydrolysis at 80 °C. It was also found that polymeric substrates of flat-sheet RO membranes may experience serious compaction at high temperature, which could subsequently affect the performance and stability of the polyamide layer. The ceramic substrates provide strong support at high temperature, and the highly stable polyamide-ceramic membranes demonstrated huge potential for RO applications under more challenging conditions.

The Performance and Spatial Distribution of Membrane Fouling in a Sequencing Batch Ceramic Membrane Bioreactor: A Pilot Study for Swine Wastewater Treatment.

The extensive application of ceramic membranes in wastewater treatment draws increasing attention due to their ultra-long service life. A cost-effective treatment for high-strength swine wastewater is an urgent and current need that is a worldwide challenge. A pilot-scale sequencing batch flat-sheet ceramic membrane bioreactor (ScMBR) coupled with a short-cut biological nitrogen removal (SBNR) process was developed to treat high-strength swine wastewater. The ScMBR achieved stable and excellent removal of COD (95.3%), NH4+-N (98.3%), and TN (92.7%), though temperature went down from 20 °C, to 15 °C, to 10 °C stepwise along three operational phases. The COD and NH4+-N concentrations in the effluent met with the discharge standards (GB18596-2001). Microbial community diversity was high, and the genera Pseudomonas and Comamonas were dominant in denitritation, and Nitrosomonas was dominant in nitritation. Ceramic membrane modules of this pilot-scale reactor were separated into six layers (A, B, C, D, E, F) from top to bottom. The total filtration resistance of both the top and bottom membrane modules was relatively low, and the resistance of the middle ones was high. These results indicate that the spatial distribution of the membrane fouling degree was different, related to different aeration scour intensities demonstrated by computational fluid dynamics (CFD). The results prove that the membrane fouling mechanism can be attributed to the cake layer formation of the middle modules and pore blocking of the top and bottom modules, which mainly consist of protein and carbohydrates. Therefore, different cleaning measures should be adopted for membrane modules in different positions. In this study, the efficient treatment of swine wastewater shows that the ScMBR system could be applied to high-strength wastewater. Furthermore, the spatial distribution characteristics of membrane fouling contribute to cleaning strategy formulation for further full-scale MBR applications.

Cross-flow photocatalytic membrane reactor (PMR) based on TiO2–AgBr–Ag–NH2-MIL-88B (Fe) /poly (ethersulfone) for enhanced removal of cefixime, anti-fouling performance and permeability

The organic-metallic framework NH2-MIL-88B (Fe) was initially synthesized using a hydrothermal process., then the TiO2–AgBr–Ag–NH2-MIL-88B (Fe) photocatalytic nanoparticles was successfully ready and used as a filler for mixed matrix membrane (MMM) poly Ether sulfone (PES) was added. A photocatalytic membrane reactor (PMR) for the degradation of cefixime aqueous solution (CFX) was fabricated using a PES-TiO2-AgBr-Ag–NH2–MIL-88B (Fe) flat sheet membrane module. FTIR, XRD, FESEM, and DRS analyses were performed to look into the produced nanoparticles' structural characteristics. Hydrophilicity and membrane surface roughness were investigated using the surface contact angle and AFM pictures test. Additionally, Cross-FESEM analysis was used to examine modifications in membrane morphology. By increasing the TiO2–AgBr–Ag–NH2-MIL-88B (Fe) nanoparticles in the polymer matrix, significant improvements were made to the membrane's hydrophilicity, porosity, pure water flux, and CFX degradation. Furthermore, the nanocomposite membranes' antifouling characteristic was assessed while the CFX solution was being filtered. The obtained results show that the flux and removal of CFX solution is improved by adding TiO2–AgBr–Ag–NH2-MIL-88B (Fe) nanoparticles to PES polymer solution up to 1 % by weight. In addition, the obtained results showed that the addition of TiO2–AgBr–Ag–NH2-MIL-88B (Fe) photocatalytic nanoparticles in the PES membrane significantly improves the antifouling properties.

Polyether sulfone flat-sheet membrane impregnated with Mn-Al layered double hydroxide nanoparticles for green microfiltration of acrylamide in cocoa products.

A new polyether sulfone (PES) membrane modified with manganese-aluminum layered double hydroxide (Mn-Al LDH) was prepared and utilized in the membrane micro-solid phase extraction (M-µSPE) of acrylamide for the first time. The analyses were conducted using HPLC-UV. The extraction efficiency of the PES membrane was enhanced two-fold with the addition of LDH. The fabricated LDH@PES was characterized using ATR-FTIR, SEM, XRD, and nitrogen adsorption/desorption isotherms. The specific surface area, average pore diameter, thickness, cross-sectional channels, and LDH particle size of the LDH@PES membrane were determined. The extraction key factors including membrane composition, desorption conditions, sample pH, and salt concentration were studied. The method was validated by determining the limit of detection, the limit of quantification, linear range, r2, matrix effect, enrichment factor, and precision. Extraction recoveries ranged from 87.4 to 103.5% with RSD < 5.9%. Finally, the method's green features were assessed with the AGREE protocol. This is the first report on the application of LDH@PES for microfiltration/extraction of acrylamide in various chocolate and cocoa products.

Response surface methodology to optimize membrane cleaning in nanofiltration of kraft black liquor

Better understanding of membrane fouling and cleaning can help implementation of membrane filtration processes in the pulp and paper industry. The aim of this study was to optimize membrane cleaning in the nanofiltration of kraft black liquor ultrafiltered permeate for the recovery of lignin. This work wants to assess whether the cleaning process removes the main foulants; as well as the economic viability of the optimized cleaning compared to a standard cleaning in a nanofiltration membrane plant on industrial scale.The optimization of membrane cleaning was investigated using the response surface methodology. The factors studied were time, temperature, and cleaning agent (Ultrasil 110) concentration, and flux recovery was used to evaluate the success of cleaning. Experiments were performed on laboratory scale where flat-sheet polymeric membranes were fouled with kraft black liquor ultrafiltered permeate and cleaned using various combinations of the three factors.The model developed predicted a flux recovery of 88 % when cleaning was performed for 60 min with a solution of 0.8 wt% Ultrasil 110 at 40 °C. The flux recovery measured experimentally with these cleaning parameters was 80 %. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy analysis confirmed that the optimized cleaning removed the main foulants from the membrane surface. Moreover, increasing the cleaning agent concentration or the cleaning temperature did not always lead to a higher flux recovery. The techno-economic evaluation revealed that 16 % of the cleaning costs could be saved by optimizing the cleaning process.

Role of Microfiltration Membrane Morphology on Nanoparticle Purification to Enhance Downstream Purification of Viral Vectors.

In the rapidly advancing realms of gene therapy and biotechnology, the efficient purification of viral vectors is pivotal for ensuring the safety and efficacy of gene therapies. This study focuses on optimizing membrane selection for viral vector purification by evaluating key properties, including porosity, thickness, pore structure, and hydrophilicity. Notably, we employed adeno-associated virus (AAV)-sized nanoparticles (20 nm), 200 nm particles, and bovine serum albumin (BSA) to model viral vector harvesting. Experimental data from constant pressure normal flow filtration (NFF) at 1 and 2 bar using four commercial flat sheet membranes revealed distinct fouling behaviors. Symmetric membranes predominantly showed internal and external pore blockage, while asymmetric membranes formed a cake layer on the surface. Hydrophilicity exhibited a positive correlation with recovery, demonstrating an enhanced recovery with increased hydrophilicity. Membranes with higher porosity and interpore connectivity showcased superior throughput, reduced operating time, and increased recovery. Asymmetric polyether sulfone (PES) membranes emerged as the optimal choice, achieving ∼100% recovery of AAV-sized particles, an ∼44% reduction in model cell debris (200 nm particles), an ∼35% decrease in BSA, and the fastest operating time of all membranes tested. This systematic investigation into fouling behaviors and membrane properties not only informs optimal conditions for viral vector recovery but also lays the groundwork for advancing membrane-based strategies in bioprocessing.

Evaluating the feasibility of direct contact membrane distillation and nanofiltration in ground water treatment through a techno-economic analysis

This study delves into the realm of water treatment by conducting a comprehensive techno-economic evaluation of direct contact membrane distillation (DCMD) and nanofiltration (NF) processes. While previous research has explored the technical aspects of membrane distillation (MD) and nanofiltration, there remains a notable gap in economic analyses. Our research aims to bridge this gap by assessing the financial feasibility of employing MD and NF technologies for water desalination. Specifically, we scrutinize the performance of hydrophobic microporous flat sheet membranes crafted from polytetrafluoroethylene (PTFE) supported by non-woven polypropylene (PP) in desalinating brackish water through DCMD and NF processes. By varying operating conditions such as flow rate and feed temperature, we evaluate the membrane's efficacy. Employing an analytical model based on heat and mass transfer equations, we predict process performance across diverse scenarios. Our model demonstrates a high level of accuracy, with flux predictions deviating by less than 10% when utilizing the Knudsen-molecular mechanism model. Furthermore, through a detailed design and economic analysis of industrial-scale units for both processes, we reveal that the cost of permeated water is lower with NF compared to DCMD. Specifically, our calculations indicate a water cost of 1.34 USD/m3 for DCMD at a feed temperature of 65 °C with an 80% recovery rate, positioning it as a competitive option among conventional desalination methods. Notably, our financial assessment highlights that steam cost constitutes the primary expense in DCMD operations, contingent upon heating value and fuel prices. Noteworthy findings suggest that natural gas emerges as the most cost-effective fuel for steam production in a DCMD plant. This study underscores the economic viability and potential cost efficiencies associated with NF over DCMD in water treatment applications.