Support Layer Research Articles

Design of a novel multi-layer enzyme membrane reactor for low-fouling, tailored production of oligodextran

Enzymatic conversion processes face challenges in controlling oligosaccharide molecular weight (Mw). Enzymatic membrane reactors (EMRs) with immobilized enzymes address this, but direct enzyme immobilization on the membrane surface can lead to deactivation and reduced hydrolysis efficiency. This study proposes a novel EMR configuration: a three-layer structure. An electrospun porous fibrous layer, modified with PDA, TA, and APTES, serves as a mechanical support layer. A commercial separation membrane is positioned below. This configuration enhances enzyme activity and selectivity. Using a “fouling-induced” technique, immobilized activity of the enzyme (i.e. dextranase) significantly increased to 11.5 µmol-isomaltose/min, surpassing incubation-immobilized dextranase (0.075 µmol-isomaltose/min). The additional layer preserves catalytic patterns, reducing fouling and ensuring high selectivity. The EMR configuration excels in producing low Mw oligosaccharides. The catalytic layer achieves 11.3 µmol-isomaltose/min, while the membrane exhibits exceptional selectivity and stability. The hydrophilic RC10 membrane with small pores performs best. This study highlights the potential of the EMR system for efficient production of stable low Mw oligosaccharides. Insights into optimizing enzyme immobilization strategies and membrane selection benefit enzymatic conversion processes.

Chemical modification of reduced graphene oxide membranes: Enhanced desalination performance and structural properties for forward osmosis

Graphene oxide (GO) nanosheets can offer a breakthrough into the development of novel and efficient laminated forward osmosis membranes, with high hydrophilicity and outstanding desalination performance. However, fabrication of desirable GO-based nanocomposite membrane which can overcome the on-going trade-off between forward osmosis (FO) performance and chemical/mechanical stability, remains to be challenging in practical application. In this study, polyethyleneimine (PEI) was used to reduce GO (rGO) and crosslink and surface modify membrane's GO sheets for the performance enhancement. The crosslinked rGO was then deposited on a hydrophilic nylon support layer (modified by polydopamine, pDA, for structural stability) using vacuum filtration method. The resulting PEI:rGO/pDA membrane showed excellent water flux (25.5 LMH), high sodium chloride (NaCl) salt rejection (98.9%), and low reverse solute flux (0.91 gMH) in lab-scale tests. The combination of crosslinking GO with PEI and modifying the support layer with polydopamine (pDA) enhanced the membranes hydrophilicity and structural stability. The incorporation of PEI into GO resulted in compacted nanochannels, improving molecular/ions separation. Moreover, the pDA coating enhanced desalination performance and reduced internal concentration polarisation effects, further improving the membrane durability and integrity through the formation of numerous binding sites for firmly anchoring with the PEI:rGO nanocomposite structure.

High-performance support-free molecular layer-by-layer assembled forward osmosis membrane incorporated with graphene oxide

Forward osmosis (FO) membranes generally have a thin-film composite (TFC) structure comprising an ultrafiltration (UF)-grade support layer and a polyamide (PA) active layer. However, the lack of high-performance membranes limits FO. To improve the FO performance, internal concentration polarization (ICP) should be controlled to reduce the water flux within the support layer. In this study, a novel support-free molecular layer-by-layer (SF-mLbL) technique using a microfiltration (MF)-grade support layer for minimum ICP was applied to produce a robust and uniform active layer, even on large pores of the support layer. Based on the location of graphene oxide (GO) nanoparticles, thin-film nanocomposite (TFN) and thin-film nanocomposite-interlayer (TFNi) membranes were fabricated. Among these, the TFNi membrane with the highest performance contained 0.7 wt% GO nanoparticles and was stacked in 15 cycles. The 0.7 wt%-15 cycles TFNi membrane showed high water flux (87.18 ± 0.15 LMH) and low reverse salt flux (5.06 ± 0.11 gMH) when deionized (DI) water and 0.5 M NaCl solution were used as feed and draw solutions, respectively, in FO mode. This study demonstrates that the SF-mLbL technique is suitable for manufacturing high-performance FO membranes.

Development of Prediction Method for Dimensional Stability of 3D-Printed Objects

Fused deposition modeling (FDM), as one of the additive manufacturing processes, is known for strong layer adhesion suitable for prototypes and end-use items. This study used a multiple regression model and statistical analysis to explore the dimensional accuracy of FDM objects. Factors such as inclination angle, layer thickness, support space, and raster angle were examined. Machine learning models (Gaussian process regression (GPR), support vector machines (SVM), and artificial neural network (ANN)) predicted dimensions using 81 datapoints. The mean squared dimensional error (MSDE) between the measured and designed surface profiles was selected as an output for the dimensional accuracy. Support spacing, layer thickness, and raster angle were determined to be statistically significant, and all factors were confirmed as significant predictors. The coefficients of determination for multiple linear regression, GPR, SVM, and ANN models were 76%, 98%, 93%, and 99%, respectively. The mean absolute errors (MAEs)—errors between the measured and the predicted MSDEs—were 0.020 mm and 0.034 mm, respectively, for GPR and SVM models. The MAEs for ANN models were 0.0055 mm for supporting cases and 2.1468 × 10−5 mm for non-supporting cases.

Influence of porous support structure and the possible presence of active layer defects on FO membrane behaviour

In forward osmosis, defects on the selective active layer and changes in the porous structure of the support layer can be detrimental factors affecting the membrane performance. This study focuses on the impacts of (i) the possible presence of defects and (ii) the changes in pore structures on the water flux and membrane selectivity via computational fluid dynamics analyses. Results suggest that diffusion of the draw solute through the support layer, i.e. internal concentration polarization, can be strongly enhanced or reduced by widening or narrowing the shape of the pore, respectively, while no significant effect on water permeation can be associated with the change in draw solution cross-flow velocity or in the loss of draw solute during filtration. Interestingly, defects within the active layer may affect the water flux exponentially as function of the defect size, suggesting the presence of a threshold below which the convective passage of contaminated water flux through the defect is not affecting the membrane productivity. Moreover, the presence of defects may not be a detrimental factor for membrane operating with high nominal rejection (>90%) and low percentage of defected area (<1%).

Biomimetic hydrophilic CuO-nanocluster/nanofibrous thin-film skeleton/hydrophilic CuO-nanocluster architecture membrane for efficient and stable solar water evaporation

Developing exquisitely structured light-absorbing materials could be a feasible approach to enhance solar evaporation performance. Herein, a CuO-nanocluster/PVDF-HFP nanofibrous thin-film skeleton/CuO-nanocluster (CPC) architecture membrane was developed via electrospinning, heating, and hydrothermal techniques. The CPC membrane architecture is similar to the triple-layer mesophyll/vein/mesophyll in a natural leaf, whereby mesophyll performs photosynthesis for plant growth and the vein acts as a support skeleton. Similarly, CPC mimicking a leaf structure possesses: (1) upper and lower hydrophilic CuO-nanoclusters to absorb sunlight, promote water supply, and prevent salt crystallization during the evaporation process; and (2) a middle nanofibrous thin-film membrane that acts as a supportive layer. The resulting CPC membrane exhibited an evaporation rate of 1.21 kg m−2 h−1 and 1.06 kg m−2 h−1 for 3.5 wt% saline water and actual industry dye wastewater, respectively. Meanwhile, the CPC membrane was applied in the cycle, continuous, and outdoor evaporation tests. In addition, the CPC membrane displayed impressive mechanical strength and flexibility, making it suitable for the long-term use in practical applications. These findings demonstrate the excellent performance of the CPC membrane for solar water evaporation and should inspire further research on developing dedicated architecture membranes for use in fields such as catalysis, sensing, energy, and other applications.

Nanofiltration membrane based on a dual-reinforcement strategy of support and selective layers for efficient Mg2+/Li+ separation

With the consumption of lithium resources increasing year by year, the investigation of high-performance salt lake lithium extraction technology is extremely important. In order to effectively separate Mg2+ and Li+ from brine, a novel charge-positive nanofiltration (NF) membrane with high permeability and excellent Mg2+/Li+ separation factor was designed by interfacial polymerization (IP) in this work. A B15C5-MX-NF membrane was fabricated by blending hydrophilic two-dimensional (2D) MXene nanosheets into a PES membrane substrate to enhance the permeability, followed by the modification of polyamide (PA) layer with a crown ether molecule (Benzo-15-crown-5) to optimize the surface properties of membrane. The PA layer thickness was effectively reduced (58 nm) due to the enhancement in the interaction between the substrate membrane and PEI by the incorporation of MXene, while the addition of B15C5 provided additional Li+ permeation channels. The B15C5-MX-NF membrane exhibited excellent permeability (16.1 L·m−2·h−1·bar−1) and superior selectivity for Mg2+/Li+ (SLi, Mg of 15.8) under the dual optimization of membrane substrate and PA layer. In addition, it was demonstrated by molecular dynamics (MD) simulations that the B15C5 molecules in the B15C5-MX-NF membranes had a specific recognition ability of Li+ to allow its preferential permeation, thereby enhancing the Mg2+/Li+ selectivity of the membranes. This study provides a new idea for the preparation of NF membranes for efficient Mg2+/Li+ separation.

Pulmonologists' Perspectives on and Access to Palliative Care for Patients With Idiopathic Pulmonary Fibrosis in South Carolina.

Idiopathic pulmonary fibrosis (IPF) is a serious illness with an unpredictable disease course and survival rates comparable with some cancers. Patients with IPF suffer considerable symptom burden, declining quality of life, and high health care resource utilization. Patients and caregivers report many unmet needs, including a desire for more education regarding diagnosis and assistance with navigating disease trajectory. Compelling evidence suggests that palliative care (PC) provides an extra layer of support for patients with serious illness. The purpose of this survey was to gain perspectives regarding PC for patients with IPF by board-certified pulmonologists in South Carolina (SC). A 24-item survey was adapted (with permission) from the Pulmonary Fibrosis Foundation PC Survey instrument. Data were analyzed and results are presented. Pulmonologists (n = 32, 44%) completed the survey; 97% practice in urbanized settings. The majority agreed that PC and hospice do not provide the same service. There were varying views about comfort in discussing prognosis, disease trajectory, and addressing advance directives. Options for ambulatory and inpatient PC are limited and early PC referral does not occur. None reported initiating a PC referral at time of initial IPF diagnosis. Pulmonologists in SC who participated in this survey are aware of the principles of PC in providing comprehensive care to patients with IPF and have limited options for PC referral. PC educational materials provided early in the diagnosis can help facilitate and guide end-of-life planning and discussions. Minimal resources exist for patients in underserved communities.

Effect of CuO–ZnO catalyst layer on proton-conducting electrochemical cell reactor for CO2 reduction reaction

A catalyst layer is coated on the fuel electrode in a proton-conducting solid oxide electrolysis cell reactor, which can optimize electrochemical performance and expand the application range of the reactor. In this work, CuO–ZnO catalyst is prepared by oxalate co-precipitation method and combined with a single cell to obtain a reactor with the structure of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) ǀ BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) ǀ NiO-BZCYYb (active layer) ǀ NiO-BZCYYb (support layer) | CuO–ZnO (catalyst layer). The electrolysis current density of this reactor with humid air as oxidant and 20%CO2–80%H2 as fuel is 2751 mA cm−2 under 1.3 V at 750 °C. It operates steadily for 138 h under 1.3 V electrolysis at 650 °C, which is better than the reactor without a catalyst layer under this condition. Additionally, CO and CH4 are detected in the exhaust gas on the fuel electrode side, and the CO selectivity reaches over 90% at 750-550 °C.

Role of imperfections in transfer of organic micro-pollutants through RO/NF membranes: Numerical study

Due to relatively low diffusivities, the rejection of organic micro-pollutants in pressure-driven membrane processes is more affected by Concentration Polarization (CP) than that of typical inorganic ions. On the other hand, it can be more sensitive to various membrane imperfections because the rejection of these solutes by intact membranes can be expected to be quite high. This makes necessary simultaneous accounting for membrane imperfections and Concentration Polarization in Reverse Osmosis and/or Nanofiltration of organic micro-pollutants. This study, for the first time, explores this problem numerically for the model of a single circular opening in a selective layer (the porous support is assumed to remain undamaged). The solute accumulated due to the CP close to the surrounding intact active layer “spills over” to the imperfection, which leads to an enhanced transmembrane solute passage as compared to the classical solution-diffusion-imperfection model assuming this passage to be controlled by the feed concentration. Our analysis reveals that the extent of this “spill-over” depends primarily on the size of imperfection (we studied the range between 0.2 μm and 20 μm) as well as on the ratio of hydraulic resistances of selective and support layers. Smaller imperfections in active layers of membranes with less permeable porous supports have larger impact. The extent of CP away from the imperfection is also important. Contrary to the trend expected for imperfection-free membranes (a better rejection of larger solutes due to a stronger steric exclusion and hindrance), the solute passage through imperfections is demonstrated to be larger for solutes with smaller diffusion coefficients, so in future experiments this can be considered a signature feature of a noticeable impact of imperfections. Quantifying their impact is important for understanding membrane aging, rational selection of membrane cleaning procedures as well as development of better membranes.

Electrooxidation of methanol and ethanol catalyzed by high-performance three-dimensional graphene-supported PdM (Co, Cu) binder-free electrode

PdM/RGN (M = Co, Cu) self-supporting composite electrodes were synthesized via a simple two-step spontaneous reduction process using Ni foam as the substrate and reduced graphene oxide as support layer. The composites were characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were performed to study the electrocatalytic activities of the prepared electrodes for methanol and ethanol oxidation. The performances of PdM/RGN for methanol and ethanol oxidation increased and then decreased as the atomic ratio of Pd to M (Co, Cu) increased. The Pd6Co1/RGN and Pd6Cu1/RGN electrodes exhibited markedly superior catalytic activity and long-term stability. The peak current densities of Pd6Cu1/RGN and Pd6Co1/RGN electrodes reached 0.36 and 0.29 A/cm2 for methanol electrooxidation and which reached 0.8 and 0.5 A/cm2 for the ethanol electrooxidation, respectively. This excellent performance is owing to the three-dimensional structure of nickel foam, the improving specific surface area and the synergistic effect between Pd and M.

Incentive strategy of dual innovation balance in green manufacturing innovation ecosystem: Based on hierarchical structure of innovation subject.

Exploratory innovation is a pivotal way to seize future opportunities in green manufacturing innovation ecosystems, and exploitative innovation is conducive to expanding existing markets and resources, so it is essential to discuss the balanced incentive strategy of dual innovation for the sustainable development of ecosystems. Based on the hierarchical structure, this paper divides the core subjects in the green manufacturing innovation ecosystem into the application layer, the support layer, and the scientific research layer, constructs the differential game model of the no-incentive scenario, the cost-sharing scenario, and the collaborative scenario, and discusses the incentive strategies of the three types of subjects and the ecosystem in the evolution process of the dual innovation balance. The conclusions are as follows: (1) The level of dual innovation balance effort of the three types of subjects decreases with the increase of resource costs and environmental construction costs and increases with the increase of innovation balance capacity; (2) Cost sharing from the application layer to the support layer and the scientific research layer can enhance the effort level of both, which in turn enhances the optimal benefits for the three types of subjects and the ecosystem as a whole; (3) In the collaborative scenario, the level of effort and total ecosystem benefits of the innovation balance of the three types of subjects are strictly better than in the no incentive scenario, and the Pareto-optimality of the three subjects and the ecosystem will be realized after the coefficients of the distribution of benefits among the three types of subjects are determined. Based on this, this paper puts forward specific suggestions for the optimization of the structural relationship of the innovation body hierarchy, the exploitation of green manufacturing resources, and the macro-planning of the management department.

Relative Insignificance of Polyamide Layer Selectivity for Seawater Electrolysis Applications.

Low-cost polyamide thin-film composite (TFC) membranes are being explored as alternatives to cation exchange membranes for seawater electrolysis. An optimal membrane should have a low electrical resistance to minimize applied potentials needed for water electrolysis and be able to block chloride ions present in a seawater catholyte from reaching the anode. The largest energy loss associated with a TFC membrane was the Nernstian overpotential of 0.74 V (equivalent to 37 Ω cm2 at 20 mA cm-2), derived from the pH difference between the anolyte and catholyte and not the membrane ohmic overpotential. Based on analysis using electrochemical impedance spectroscopy, the pristine TFC membrane contributed only 5.00 Ω cm2 to the ohmic resistance. Removing the polyester support layer reduced the resistance by 79% to only 1.04 Ω cm2, without altering the salt ion transport between the electrolytes. Enlarging the pore size (∼5 times) in the polyamide active layer minimally impacted counterion transport across the membrane during electrolysis, but it increased the total concentration of chloride transported by 60%. Overall, this study suggests that TFC membranes with thinner but mechanically strong supporting layers and size-selective active layers should reduce energy consumption and the potential for chlorine generation for seawater electrolyzers.

A novel multifunctional chitosan-gelatin/carboxymethyl cellulose-alginate bilayer hydrogel containing human placenta extract for accelerating full-thickness wound healing

The replication of skin's dermal and epidermal morphology within a full-thickness wound using a bi-layer hydrogel to cater to their distinct needs is a compelling pursuit. Moreover, human placenta extract (HPE), containing a diverse array of bioactive agents, has proven to be effective in promoting the wound healing process and enhancing epidermal keratinocytes. This study presents a multifunctional bi-layer hydrogel incorporating HPE for accelerating full-thickness wound healing through sustained HPE release, inhibition of bacteria invasion, and promotion of cell proliferation. The upper layer of the scaffold, known as the dressing layer, is composed of carboxymethyl cellulose and sodium alginate, serving as a supportive layer for cell proliferation. The under layer, referred to as the regenerative layer, is composed of chitosan and gelatin, providing an extracellular matrix-like, porous, moist, and antibacterial environment for cell growth. The scaffold was optimized to replicate the morphology of the dermal and epidermal layers, with suitable fibroblast infiltration and a pore size of approximately 283μm. Furthermore, the degradation rate of the samples matched the wound healing rate and persisted throughout this period. The sustained HPE release rate, facilitated by the degradation rate, was optimized to reach ~98% after 28 days, covering the entire healing period. The samples demonstrated robust antibacterial capabilities, with bacterial inhibition zone diameters of2.56±0.10cm and 2.63±0.12cm for S. aureus and E. coli, respectively. The biocompatibility of the samples remained at approximately 68.33±4.5% after 21 days of fibroblast cell culture. The in vivo experiment indicated that the HPE@Bilayer hydrogel promotes the formation of new blood vessels and fibroblasts during the early stages of healing, leading to the appropriate formation of granulation tissue and a wound contraction rate of (79.31±3.1)%. Additionally, it resulted in the formation of a thick epidermal layer (keratinization) that effectively covered all the impaired areas, achieving a wound contraction rate of 95.83±6.3% at the late stage of wound healing. Furthermore, immunohistochemistry staining for CD31 and TGF-β revealed that the HPE@Bilayer group had 22 blood vessels/field and 34%−66% immunoactive cells, respectively, after 14 days of healing. However, by day 21, angiogenesis and TGF-β expression had declined, demonstrating that the wounds had been successfully treated with minimal scarring.

Hierarchical metal-organic framework-functionalized PVDF tree-like nanofiber membrane for high-efficient photothermal membrane distillation

The development of membrane with strong sunlight absorption and high energy efficiency is the key to improve the water production efficiency in photothermal membrane distillation (PMD). In this paper, a hierarchical Cu-based metal–organic framework-functionalized polyvinylidene fluoride (PVDF) tree-like nanofiber membrane (Cu-CAT@TLNM-TLNMs) was developed for high-efficient PMD. The Cu-CAT@TLNM-TLNM was prepared by in-situ growth of Cu-CAT on the surface of PVDF tree-like nanofiber membrane (TLNM) as photothermal layer and PVDF TLNM as support layer, which exhibited excellent photothermal conversion performance, high energy utilization and high permeate flux. The PVDF TLNM with high specific surface area provided more active sites for the growth of Cu-CAT, thus forming a uniform Cu-CAT nanoarray. The spinous structure of the Cu-CAT photothermal layer can increase the length of the light-matter interaction and improve light absorption. In addition, the tree-like structure of the support layer with high porosity and small pore size can improve the permeate flux and long-term stability. Under the illumination of 1 kW·m−2, the surface temperature of the Cu-CAT@TLNM-TLNMs reached about 80 °C within 50 s, with a permeate flux of 1.37 kg·m−2·h−1, a salt rejection of >99.99 %, and a photothermal conversion efficiency of 76 %. More importantly, the permeate flux of the Cu-CAT@TLNM-TLNMs was still stable at 0.79 kg·m−2·h−1 with a salt rejection of >99.99 % after 84 h of continuous operation. This photothermal nanofiber composite membrane can be applied to solve the problem of freshwater shortage in areas where freshwater and fuel resources are scarce and solar energy is abundant.

Overcoming the trade-off between water flux and salt rejection of an RO membrane via simultaneous optimization using highly porous microstructured support and sulfonated porous organic polymer-based polyamide active layer

Many researchers have devoted much effort to addressing the trade-off between water flux and salt rejection of reverse osmosis (RO) membranes till now, but it still needs to be solved. In this work, as a strategy to overcome the trade-off, simultaneous optimization was carried out with porous organic polymers (POPs) and highly porous microstructure support (HPμS) layers featuring regularly arranged columnar macrovoids formed by carefully adjusting the thermodynamic instability of a polymer solution. POPs were introduced into the active layer of an RO membrane to impart the water channel and hydrophilicity. POP fillers were functionalized with amine and sulfonic groups, and the synthesized POPs were introduced into different phases depending on sulfonation. Sulfonated POPs with high hydrophilicity provided additional water pathways and hydrophilic properties while maintaining the active layer's thickness, notably improving water permeability. Surprisingly, the simultaneous optimization not only enhanced the permselectivity further but also made thin-film nanocomposite (TFN) membranes overcome the trade-off because the shortened diffusion pathway by the HPμS was more beneficial for improving water permeability than salt permeability. As a result, the simultaneously optimized TFN exhibited 2.2 to 2.7 times higher water permeability and 2.6%p to 3.4%p higher salt rejection than a control TFC membrane.

High aspect-ratio sub-500 nm UV-PDMS bilayer stamps by means of hybrid thermal-ultraviolet curing for resonant nanopillars fabrication through soft UV-NIL

A novel protocol for the fabrication of bilayer stamps for soft UV-NIL is presented. The patterned layer is composed of a commercially available UV-curable PDMS, while a quartz backplane acts as support layer. The pattern reproduced in the stamp through direct casting comes from a hard template and is composed of nanopillar arrays with 250–300 nm of diameter and 300–400 nm in height. The master template with nanoholes is treated with a self-assembled monolayer before pattern reproduction for improved separation of UV-PDMS layer. The hybrid cross-linking protocol includes a thermal and a UV process, and parameters of the former are investigated for best results. The pattern was reproduced in a resist on a Si sample by means of soft UV-NIL, and the imprinted nanohole arrays show dimensions coherent with the stamp. Finally, its application in the fabrication of resonant nanopillars for sensing purposes is briefly described. This is, to the best of our knowledge, the first time a hybrid thermal-ultraviolet curing of UV-PDMS has been reported and that protruding nanostructures with aspect-ratio higher than 1 in soft UV-NIL stamps have been demonstrated.

Preparation, characterization and application of BaZr0.1Ce0.7Y0.2O3-δ for a high-performance and stable proton ceramic electrochemical cell

The high sintering temperature (＞1500 °C) of the electrolyte is the main challenge for the application of proton ceramic electrochemical cells (PCECs). In this work, we prepare BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolyte materials by various synthetic routes, compare their physicochemical properties and optimize their applications in PCEC. The BZCYs powder prepared by the solid state reaction method shows a large grain size of 2–3 μm and is used in the support layer. The optimal proportion of the support is determined according to the thermal expansion characterization. The BZCYp powder from the ultrasonic-assisted co-precipitation method presents well dispersed particles of 30∼50 nm and is used as the electrolyte layer and in the fuel electrode layer. The electrolyte becomes very dense after co-sintering with the support at 1400 °C without any sintering aids, giving a low conducting activation energy of 0.26 eV. The single cell demonstrates excellent performance and good stability. Under steam electrolysis mode, the cell gives 840 and 260 mAcm−2 @1.3V at 600 °C and 500 °C. Under cell mode, the cell displays 0.46 and 0.21Wcm−2@0.7V at 600 °C and 500 °C, respectively.

Performance analysis and design for an asymmetric membrane of a hollow fiber hemodiafilter with a two-layer membrane model

A hemodiafilter model including the two-layer membrane model based on the irreversible thermodynamics was first introduced, which considers the convective solute flux besides the diffusive solute one. This model makes it possible to analyze the solute transfer of an asymmetric membrane which is assumed to be equivalent to the two-layer membrane consisting of a skin layer and a porous support layer. Verification was performed with in-vitro data on commercial hemodiafilters for solutes of middle molecular weight, and the results were good in solute clearances. In order to increase the clearance of middle molecular weight solutes in high-performance membranes, it is necessary to increase the solute diffusive permeability in the support layer. Through the model simulation, the author was able to quantitatively grasp the relationship between myoglobin clearance versus membrane microstructure parameters and membrane thickness and to clarify the direction of increase in solute transfer amount. In addition, it made clear that the convective solute transfer is more predominant than the diffusive solute one in ultrafiltration effect of the hemodiafilter with the asymmetric membrane.

Strategy of Development on Zeolite Membrane for Forward Osmosis Operation; Effects of Structural Parameter of Support Layer and Si/Al Ratio of ZSM-5 Layer on Water Flux

Strategy of Development on Zeolite Membrane for Forward Osmosis Operation; Effects of Structural Parameter of Support Layer and Si/Al Ratio of ZSM-5 Layer on Water Flux