Solute Permeability Research Articles

Fluctuating hydrodynamics of an autophoretic particle near a permeable interface

We study the autophoretic motion of a spherical active particle interacting chemically and hydrodynamically with its fluctuating environment in the limit of rapid diffusion and slow viscous flow. Then, the chemical and hydrodynamic fields can be expressed in terms of integrals. The resulting boundary-domain integral equations provide a direct way of obtaining the traction on the particle, requiring the solution of linear integral equations. An exact solution for the chemical and hydrodynamic problems is obtained for a particle in an unbounded domain. For motion near boundaries, we provide corrections to the unbounded solutions in terms of chemical and hydrodynamic Green's functions, preserving the dissipative nature of autophoresis in a viscous fluid for all physical configurations. Using this, we give the fully stochastic update equations for the Brownian trajectory of an autophoretic particle in a complex environment. First, we analyse the Brownian dynamics of particles capable of complex motion in the bulk. We then introduce a chemically permeable planar surface of two immiscible liquids in the vicinity of the particle and provide explicit solutions to the chemo-hydrodynamics of this system. Finally, we study the case of an isotropically phoretic particle hovering above an interface as a function of interfacial solute permeability and viscosity contrast.

Analysis of the effect of permeant solutes on the hydraulic resistance of the plasma membrane in cells of Chara corallina.

In the cells of Chara corallina, permeant monohydric alcohols including methanol, ethanol and 1-propanol increased the hydraulic resistance of the membrane (Lpm-1). We found that the relative value of the hydraulic resistance (rLpm-1) was linearly dependent on the concentration (Cs) of the alcohol. The relationship is expressed in the equation: rLpm-1 = ρmCs + 1, where ρm is the hydraulic resistance modifier coefficient of the membrane. Ye et al. (2004) showed that membrane-permeant glycol ethers also increased Lp-1. We used their data to estimate Lpm-1 and rLpm-1. The values of rLpm-1 fit the above relation we found for alcohols. When we plotted the ρm values of all the permeant alcohols and glycol ethers against their molecular weights (MW), we obtained a linear curve with a slope of 0.014M-1/MW and with a correlation coefficient of 0.99. We analyzed the influence of the permeant solutes on the relative hydraulic resistance of the membrane (rLpm-1) as a function of the external (π0) and internal (πi) osmotic pressures. The analysis showed that the hydraulic resistance modifier coefficients (ρm) were linearly related to the MW of the permeant solutes with a slope of 0.012M-1/MW and with a correlation coefficient of 0.84. The linear relationship between the effects of permeating solutes on the hydraulic resistance modifier coefficient (ρm) and the MW can be explained in terms of the effect of the effective osmotic pressure on the hydraulic conductivity of water channels. The result of the analysis suggests that the osmotic pressure and not the size of the permeant solute as proposed by (Ye et al., J Exp Bot 55:449-461, 2004) is the decisive factor in a solute's influence on hydraulic conductivity. Thus, characean water channels (aquaporins) respond to permeant solutes with essentially the same mechanism as to impermeant solutes.

Polyacrylonitrile Ultrafiltration Membrane for Separation of Used Engine Oil

The separation of used engine oil (UEO) with an ultrafiltration (UF) membrane made of commercial copolymer of poly(acrylonitrile-co-methyl acrylate) (P(AN-co-MA)) has been investigated. The P(AN-co-MA) sample was characterized by using FTIR spectroscopy, 13C NMR spectroscopy, and XRD. The UF membrane with a mean pore size of 23 nm was fabricated by using of non-solvent-induced phase separation method—the casting solution of 13 wt.% P(AN-co-MA) in dimethylsulfoxide (DMSO) was precipitated in the water bath. Before the experiment, the used engine oil was diluted with toluene, and the resulting UEO solution in toluene (100 g/L) was filtered through the UF membrane in the dead-end filtration mode. Special attention was given to the evaluation of membrane fouling; for instance, the permeability of UEO solution was dropped from its initial value of 2.90 L/(m2·h·bar) and then leveled off at 0.75 L/(m2·h·bar). However, the membrane cleaning (washing with toluene) allowed a recovery of 79% of the initial pure toluene flux (flux recovery ratio), indicating quite attractive membrane resistance toward irreversible fouling with engine oil components. The analysis of the feed, retentate, and permeate by various analytical methods showed that the filtration through the UF membrane made of P(AN-co-MA) provided the removal of major contaminants of used engine oil including polymerization products and metals (rejection—96.3%).

Moment analysis method for the determination of permeation kinetics of coumarin at lipid bilayers of liposomes by using capillary electrophoresis.

A method was developed for studying mass transfer kinetics at lipid bilayers of liposomes. Elution peaks of coumarin were measured by liposome electrokinetic chromatography (LEKC). Four types of phospholipids having different alkyl chains were used for preparing liposomes, which were used as pseudo-stationary phases in LEKC systems. Rate constants of permeation across lipid bilayers of liposomes or of adsorption at lipid membranes were determined by analyzing the first absolute and second central moments of the elution peaks measured by LEKC. The rate constants of permeation or adsorption tend to decrease with an increase in the carbon number of the alkyl chains of phospholipids. It was demonstrated that the moment analysis of elution peak profiles measured by LEKC is effective for determining lipid membrane permeability or adsorption kinetics. Compared with other conventional techniques, the method has some advantages for studying mass transfer kinetics at lipid bilayers. Solute permeation across or solute adsorption at real lipid bilayers of liposomes is analyzed. The principle of the method is the analysis of separation behavior in LEKC, which is different from that of the other ones. It is expected that the method contributes to the kinetic study of mass transfer at lipid bilayers from various perspectives.

Fabrication and characterization of poly(methyl vinyl ether maleic anhydride) blended poly(lactic acid) ultrafiltration membrane with upgraded antifouling and separation performance

In this present study, a novel environment-friendly bio-polymeric hybrid ultrafiltration membrane was fabricated by incorporating poly(methyl vinyl ether maleic anhydride) (PMVEAMA) into the poly(lactic acid) (PLA) polymer matrix. The integration of PMVEAMA into PLA significantly altered the membrane's structural morphology, functional characteristics, and filtration performance. As a result, key functional parameters like membrane porosity and water content were increased, which exhibiting the improved hydrophilicity. Furthermore, the molecular weight cut-off of the PLA/PMVEAMA membrane reached up to a maximum of 66.5 KDa with an average pore size of 9.14 nm, subsequently improving the flux of the membrane up to 2.8 times than PLA membrane. The functional capacity of the synthesized membrane was further assessed by testing its ability to filter toxic chlorophenolic compounds. Rejection studies reveal that the PLA/PMVEAMA membrane achieved a rejection efficiency of 44.64 % pentachlorophenol (PCP) and 51.85 % 2,4-dichlorophenol (DCP). Moreover, fouling studies revealed enhanced PCP and DCP flux recovery ratios of 50.94 % and 51.40 %, respectively, with a significant reduction in the flux decline rate. Additionally, the synthesized PLA/PMVEAMA membranes improved stability and regenerative properties up to 12 filtration cycles and antifouling properties highlight its potential to filter chlorophenolic compounds from wastewater.

Effect of Fine Particle Content on Solution Flow and Mass Transfer of Ion-Adsorption-Type Rare Earth Ores

Fine particle content significantly affects the in situ leaching of ion-adsorption-type rare earth ores. This study investigated the effect of fine particle content on solution flow and mass transfer in leaching. The results showed that with the increase in fine particle content, the peak concentration and peak time of rare earth increased. When the fine particle content exceeded 20%, all ion-exchangeable-phase rare earth ions could be replaced with a low dosage of the leaching solution. The leachate flow rate exhibited multi-stage variation, influenced by solution permeation, ion exchange, and fluctuations in accumulated liquid height. A mass transfer analysis showed that a higher fine particle content corresponded to a smaller plate height and a larger plate number of theoretical plates. As fine particle content increased, the final rising height of capillary water decreased, with rising rates varying across different stages for the samples. Moreover, an increase in fine particle content from 5% to 20% resulted in a 94% decrease in the samples’ permeability coefficients. A mechanism analysis showed that when the fine particle content was higher, the fine particles were embedded in the gaps between coarse particles, and the ore particles in the sample were arranged continuously, resulting in a lower permeability coefficient. Then, the leaching solution could penetrate uniformly, which was beneficial for reducing leaching blind spots and improving leaching efficiency. However, excessive fine particle content might have detrimental effects. Based on these results and considering actual mining conditions, the optimal fine particle content for rare earth leaching is 20%.

Leaching process assisted by cetyltrimethylammonium chloride for weathered crust elution-deposited rare earth ores: Leaching behavior, kinetic analysis and interfacial regulation

Magnesium salts are commonly employed as ammonium-free leaching agents in the extraction of weathered crust elution-deposited rare earth ores (WCE-REO). Nonetheless, these salts frequently face technical challenges, including relatively low leaching rates and inadequate permeability in the in-situ leaching process. In this study, cetyltrimethylammonium chloride (CTAC) was used as a novel leaching aid agent to improve the rare earth leaching process. The effects of CTAC and pH on the rare earth leaching behavior and permeability was investigated. The leaching kinetic model was established and the regulation mechanism by which CTAC interacts with clay mineral surfaces was revealed for rare earth leaching process enhanced by CTAC. The results indicate that the appropriate amount of CTAC can increase the permeation velocity by 1.16×10−4 cm·s−1. Moreover, the rare earth leaching rate increased from 83.75 % to 95.65 %, accompanied by a reduction in leaching equilibrium time under optimal conditions. However, a higher concentration of CTAC results in a lower permeation velocity due to the increasing viscosity and the hydrophilicity. The relatively low pH will affect permeability of composite leaching agent in the ore pillar, diminishing its beneficial impact on rare earth leaching. The kinetic equation, fitted by the shrinking core model, suggests that the leaching adheres to an internal diffusion control mechanism, underscoring mass transfer as the pivotal limiting factor in rare earth leaching. CTAC reduces surface tension and viscosity, facilitating the permeation of the leaching solution into the rare earth ore. Furthermore, CTAC can be adsorbed on the surface of rare earth mineral particles, increasing the contact angle of clay minerals, elevating the Zeta potential, and diminishing the thickness of the diffusion layer, thus promoting mass transfer during leaching. The results of atomic force microscopy (AFM) analysis shows that the appropriate amount of CTAC adsorbed on rare earth ores can decreases the thickness of the hydration film on the particles’ surface, further improving the mass transfer efficiency during the leaching process. The findings of this study offer new insights into the green and efficient extraction of rare earth resources from both theoretical and technical perspectives.

Relative contributions of mobility and partitioning to volatile fatty acid flux during electrodialysis

Economically valuable volatile fatty acids (VFAs) are sustainably produced via fermentation processes. To use VFAs downstream, they must be recovered using technologies like electrodialysis (ED). Solute transport properties (i.e., partition coefficient (K), diffusion coefficient (D), and permeability (P=KD)) govern flux in ED. Therefore, to advance understanding of VFA flux through anion exchange membranes (AEMs) in ED, we aimed to elucidate the relative contributions of VFA partitioning and mobility to their flux. Accordingly, for VFAs of different sizes (C1–C5) and inorganic anions (Cl–, Br–), we measured their fluxes during ED, permeabilities, and partition coefficients, and calculated the diffusion coefficients. We then evaluated the correlations between flux and transport properties and between transport properties and anion physicochemical properties. Results showed VFA flux had a strong correlation with permeability (R2=0.94, p<0.01), consistent with flux described by the Nernst-Planck equation. Further, while there was a negative correlation between VFA flux and partition coefficient (R2=0.46, p=0.21), there was a positive correlation between VFA flux and diffusion coefficient (R2=0.95, p<0.01) which showed VFA mobility governed VFA flux. We observed a negative correlation between VFA diffusion coefficient and carbon–chain length which was attributed to steric hindrance, and a positive correlation between partition coefficient and carbon chain-length which we attributed to hydrophobicity and polarizability. This work provides fundamental insight on interactions between VFAs and AEMs which affect anion flux during ED.

Moment analysis method for determination of rate constants of solute permeation across interface of spherical molecular aggregates by means of high-performance liquid chromatography

A moment analysis method was developed for the study of solute permeation at the interface of spherical molecular aggregates. At first, new moment equations were developed for determining the partition equilibrium constant (Kp) and permeation rate constants (kin and kout) of solutes from the first absolute (μ1A) and second central (μ2C) moments of elution peaks measured by using high-performance liquid chromatography (HPLC). Then, the method was applied to the analysis of mass transfer phenomena of three solutes, i.e., hydroquinone, resorcinol, and catechol, at the interface of sodium dodecylsulfate (SDS) micelles. HPLC data were measured by using an ODS column and an aqueous phosphate buffer solution (pH = 7.0) as the mobile phase solvent. Pulse response experiments were conducted while changing SDS concentration (5 - 20 mmol dm−3) in the mobile phase under the conditions that the surface of ODS stationary phase was dynamically coated by SDS monomers. In order to demonstrate the effectiveness of the moment analysis method using HPLC, the values of Kp, kin, and kout were determined for the three solutes as 35 - 69, 2.4 × 10−8 - 1.4 × 10−6 m s−1, and 7.0 × 10−10 - 2.1 × 10−8 m s−1, respectively. Their values increase with an increase in the hydrophobicity of the solutes. The method has some advantages for the study of interfacial solute permeation of molecular aggregates. For example, neither immobilization nor chemical modification of both solute molecules and molecular aggregates is required when elution peaks are measured by using HPLC. Interfacial solute permeation takes place in the mobile phase without any chemical reaction or physical action on molecular aggregates. The values of Kp, kin, and kout were analytically determined from those of μ1A and μ2C by using the moment equations. The results of this study must contribute to the dissemination of an opportunity for studying the interfacial solute permeation of molecular aggregates to many researchers because of extremely high versatility of HPLC.

Long-Term Performance Evaluation and Fouling Characterization of a Full-Scale Brackish Water Reverse Osmosis Desalination Plant

Water scarcity in Tunisia’s semi-arid regions necessitates advanced brackish water desalination solutions. This study evaluates the long-term performance and fouling characteristics of the largest brackish water reverse osmosis desalination plant in southern Tunisia over a period of 5026 days. The plant employs two-stage spiral-wound membrane elements to treat groundwater with a salinity of 3.2 g L−1. The pre-treatment process includes oxidation, sand filtration, and cartridge filtration, along with polyphosphonate antiscalant dosing. Membrane performance was assessed through the analysis of operational data, standardization of permeate flow (Qps) and salt passage (SPs), and the calculation of water (A), solute (B), and ionic (Bj) permeability coefficients. Over the operational period, there was an increase in operating pressure, pressure drop, and permeate conductivity, accompanied by a gradual increase in SPs as well as in the solute B and ionic Bj permeability coefficients. The average B increased by 82%, reflecting a decrease in solute rejection over time. Additionally, the ionic permeability coefficients for both SO42− and Cl− ions increased, with Cl− showing an 88% increase and SO42− showing an 87% increase. The produced water’s salinity increased by 67%, indicating a significant loss of membrane performance. To identify the cause of these problems, membrane characterization was analyzed using visual inspection, X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR). The characterization revealed the complex nature of the foulants, with a predominant presence of calcium sulfate, along with minor quantities of calcite, dolomite, and silica. The extent of CaSO4 deposition suggests poor antiscaling efficiency, highlighting the critical importance of selecting an effective antiscalant to mitigate membrane fouling.

Forward osmosis membrane process: A review of temperature effects on system performance and membrane parameters from experimental studies

Forward osmosis (FO) offers a promising solution for concentration and material recovery, characterized by its low energy consumption and high separation efficiency. Temperature exerts a significant influence on FO, affecting permeation performance, membrane characteristics, and solution chemistry. The review article shows that increasing temperatures enhance forward permeate flux and solvent recovery by modifying mass transfer coefficients, membrane structure, and solution properties like osmotic pressure, diffusivity, and viscosity. This helps alleviate concentration polarization, a key challenge in FO applications. However, higher temperatures can exacerbate reverse solute flux, diminish solute rejection, and amplify membrane fouling, impacting operational efficiency and effluent quality. Studies involving thermoresponsive compounds or high-solute-content solutions yield conflicting results, further complicated by thermo-osmosis in scenarios with temperature gradients between solutions. In water and wastewater treatment, a huge quantity of solutions is treated, and temperature control is difficult. Managing solution temperatures through the utilization of waste hot streams or available heat sources can offer a viable strategy for enhancing system efficiency and mitigating the detrimental impacts of temperature fluctuations, while the solution volume should be effectively reduced before the treatment. A nuanced comprehension of temperature’s impacts is imperative for refining FO systems and addressing challenges across various industrial and environmental sectors.

DIPG-08. PROBING THE BLOOD-BRAIN-TUMOR-BARRIER WITH A MICROVASCULAR MODEL OF DIFFUSE MIDLINE GLIOMA

Abstract BACKGROUND Pediatric diffuse midline glioma (DMG) is a uniformly fatal brain tumor in children, with most patients surviving less than 12 months. Current treatment for DMG is limited, and outcomes for this tumor have not improved. The blood-brain-barrier (BBB) remains a key challenge for DMG therapeutics, preventing most drugs from entering brain tissue. Functional characterization of the blood-brain-tumor-barrier (BBTB) – the interaction between tumors and BBB vasculature – remains largely unexplored for DMG. There is a need for a preclinical model of DMG that can probe the functional, physiological, and biological properties of the BBTB in vitro as a platform to evaluate therapeutic efficacy that is representative of human physiology. METHODS To generate an in vitro model of DMG with human microvasculature (DMG-BBTB model), we co-cultured DMG neurospheres, human brain microvascular endothelial cells, human brain vascular pericytes, and human astrocytes. Cells are simultaneously seeded into microfluidic devices at varied concentrations within a fibrin matrix. Self-assembled microvascular networks are formed within 7-8 days and used for downstream functional and phenotypic assays. RESULTS Vascular morphology and solute permeability in microvascular networks are influenced by cell identity, growth pattern, and relative concentration. We show that DMG neurospheres exhibit different patterns of growth when co-cultured as uniform spheroids versus single cells in suspension. Devices representing each growth pattern are further characterized for paracellular diffusion and permeability compared to devices without DMG cells through perfusion of high molecular weight dextran. Permeability values are correlated to biologic features such as the abundance and localization of junctional proteins and transporters. CONCLUSIONS We developed a platform to evaluate the microvasculature of the DMG BBTB as a tool to develop new therapies informed by vascular biology. We probed the functional, physiological, and biological properties of the human DMG BBTB in vitro, and in ongoing work are assessing approved and experimental therapeutics.

Determining water and solute permeability of reverse osmosis membrane using a data-driven machine learning pipeline

Water (A) and solute permeability (B) are the key parameters characterizing the performance of reverse osmosis (RO) membranes. However, determining A and B requires multiple times of experiments that are time-consuming. Thus, developing a method to estimate A and B quickly has been encouraged. This study introduces a data-driven machine learning (ML) pipeline designed to predict A and B for RO membranes. The ML pipeline addresses all stages for estimating A and B, from data preprocessing to practical guidance on developed models. In particular, the membrane composition data, an overlooked essential component detailing A and B, was employed as features for the ML models. Sixteen ML models were tested, and categorical boost (CatBoost) and extremely randomized trees (ET) were selected as the best models for A and B, respectively. The selected ML models were retrained using the minimum yet effective features identified through feature importance analysis. Consequently, the retrained ML models exhibited high accuracy in predicting A and B (Radj,test2 = 0.925/MAEtest = 0.246 for A; Radj,test2 = 0.986/MAEtest = 0.069 for B), demonstrating the viability of a data-driven approach for parameter estimation. Moreover, this study highlights that RO membrane performance can be gauged effectively using membrane composition data and a limited set of operating conditions.

Cross-Linked Cellulose Nanocrystal Membranes with Cholesteric Assembly.

Forming membranes by tangential flow deposition of cellulose nanocrystal (CNC) suspensions is an attractive new approach to bottom-up membrane fabrication, providing control of separation performance using shear rate and ionic strength. Previously, the stabilization of these membranes was achieved by irreversibly coagulating the deposited layer upon the permeation of a high-ionic-strength salt solution. Here, we demonstrate for the first time the chemical cross-linking of carboxyl-containing TEMPO-oxidized CNCs by Ag(I)-catalyzed oxidative decarboxylation and the stabilization of CNC membranes using this post-treatment. Cross-linking of TEMPO-CNCs was first demonstrated in suspension via turbidity, dynamic light scattering, and storage (G') and loss (G″) moduli measurements. Membranes were formed by filtering a 0.15 wt % TEMPO-CNC suspension onto a porous support, followed by permeation of the cross-linking solution containing AgNO3 and KPS through the deposited layer. Rejection for Blue Dextran with a 5 kDa molecular weight was 95.3 ± 1.9%, 90.6 ± 3.7%, and 95.9 ± 1.0% for membranes made from suspensions of TEMPO-CNC, desulfated TEMPO-CNC. and TEMPO-CNC with 100 mM NaCl, respectively. Suspensions with added NaCl led to membranes with improved stability and cholesteric self-assembly in the membrane layer. Membranes subjected to cross-linking post-treatment remained intact upon drying, while those stabilized physically using 200 mM AlCl3 solution were cracked, demonstrating the advantage of the cross-linking approach for scale-up, which requires drying of the membranes for module preparation and storage.

Transforming the Stability, Encapsulation, and Sustained Release Properties of Calcium Alginate Beads through Gel-Confined Coacervation.

Calcium alginate (Ca2+/alginate) gel beads find use in diverse applications, ranging from drug delivery and tissue engineering to bioprocessing, food formulation, and agriculture. Unless modified, however, these gels have limited stability in alkaline media (including phosphate buffers), and their high solute permeability limits their ability to efficiently encapsulate and slowly release water-soluble small molecules. Here, we show how these limitations can be addressed by mixing the alginate solutions used in the bead preparation with the nontoxic anionic polymer polyphosphate (PP). Upon complexing Ca2+ ions, PP undergoes complex coacervation (i.e., liquid/liquid phase separation into a Ca2+/PP-rich coacervate phase and a dilute supernatant phase). At lower PP concentrations, the Ca2+/PP coacervate appears to simply remain dispersed within the beads. Though its presence makes the beads more stable in alkaline media (phosphate-buffered saline and seawater), it has little impact on the bead stiffness, morphology, and (at least in the absence of substantial payload/coacervate association) encapsulation and release properties. When the PP concentrations exceed a critical value, however, Ca2+/PP coacervation within the gelling Ca2+/alginate beads collapses the resulting beads into more compact, interpenetrating polymer networks. Besides their enhanced stability to alkaline environments, these hybrid beads exhibit irregular morphologies with wrinkled and dimpled surface structures and macroscopic (closed) internal pores, and their collapse into these polymer-rich networks also makes them significantly stiffer than their PP-free counterparts. Crucially, these beads also exhibit a much lower solute permeability, which enables highly efficient encapsulation and multiday release of water-soluble small molecules (with the beads encapsulating >90% of the added model payload and sustaining its release over 3-5 d). Collectively, these findings provide a mild and simple (single-step) pathway to generating ionically cross-linked alginate beads with significantly enhanced stability, encapsulation efficiency, and sustained release.

Numerical modeling and performance analysis of anode with porous structure for aluminum-air batteries

Aluminium-air batteries have been considered as one of the most promising next-generation energy storage devices. In this work, based on COMSOL Multiphysics, we firstly explored the effect of 3D pore size structure change on the permeation performance of the solution. The results showed that enhancing the permeation stroke of permeable solutions was beneficial to expanding the electrode reaction contact area, but it would reduce the permeation and corrosion resistance effects. For this reason, we further carried out a secondary study of TPMS structure on fluid permeation and its electrochemical performance based on the TPMS structure modelling mechanism. The results showed that the TPMS structure possessed both good solution permeation reaction rate and good corrosion resistance. Additionally, in order to further verify the validity of the simulation data, we carried out the validation of the self-corrosion rate, discharge properties, and electrochemical properties. From the final data, the discharge voltage of the TPMS structure was only 1.43 V, but its corrosion current and polarisation impedance were 2.207 × 10−2 A/cm2 and 2.2 Ω∙cm2, respectively. At the same time, the structure also had good solution permeability. Therefore the porous anode structure design for aluminium-air batteries in three-dimensional state is preferred.

Impact of temperature and forward osmosis membrane properties on the concentration polarization and specific energy consumption of hybrid desalination system.

This study investigates how temperature and forward osmosis (FO) membrane properties, such as water permeability (A), solute permeability (B), and structural parameter (S), affect the specific energy consumption (SEC) of forward osmosis-reverse osmosis system. The results show that further SEC reduction beyond the water permeability of 3 LMH bar-1 is limited owing to high concentration polarization (CP). Increasing S by 10-fold increases FO recovery by 177.6%, causing SEC decreases by 33.6%. However, membrane with smaller S also increases external CP. To reduce SEC, future work should emphasize mixing strategies to reduce external CP. Furthermore, increasing the temperature from 10 to 40 °C can reduce SEC by 14.3%, highlighting the energy-saving potential of temperature-elevated systems. The factorial design indicates that at a lower temperature, increasing A and decreasing S have a more significant impact on reducing SEC. This underlines the importance of developing advanced FO membranes, particularly for lower-temperature processes.

Mathematical and statistical modeling of glucose permeation through ultrafiltration system

Membrane bioreactors (MBRs) have been recently proposed for enhancing enzymatic hydrolysis of lignocelluloses by simultaneously and selectively removing the produced sugars from the reaction system. An inverted dead-end MBR with polyethersulfone membrane was used to investigate glucose permeation. The effects of glucose concentration, water flowrate, and membrane molecular weight cut-offs (MWCO), were investigated. The developed diffusion-convective model predicted glucose permeation with R2 value of 0.96. The statistical analysis showed that the effects of glucose concentration and water flowrate were significant, with P-value less than 0.05 for both, whereas that of the MWCO was insignificant (P-value of 0.66). This is the first attempt to mathematically describe the behavior of glucose across ultrafiltration membrane, while taking into consideration both molecular diffusion and convective flow. The findings of this work are essential for understanding the behavior and enhancing the performance of solute permeation through ultrafiltration membrane, which is the heart of many processes.

Overcoming the Trade-Off between Methanol Rejection and Proton Conductivity via Facile Synthesis of Crosslinked Sulfonated PEEK Proton Exchange Membranes

In this work, homogeneous, thin-film proton exchange membranes (PEMs) with superior proton conductivities and high methanol rejection were fabricated via a facile synthesis procedure. Sulfonated polyether ether ketone (sPEEK) was crosslinked via a Friedel–Crafts reaction by α,α′-dichloro-p-xylene, a non-hazardous and hydrophobic compound. PEMs with varying crosslinking and sulfonation degrees were fabricated to overcome the traditional trade-off between methanol rejection and proton conductivity. The sulfonation of PEEK at 60 °C for 24 h resulted in a sulfonation degree of 56%. Those highly sulfonated backbones, in combination with a low membrane thickness (ca. 20 µm), resulted in proton conductivities superior to Nafion 117. Furthermore, X-ray photoelectron spectroscopy proved it was possible to control the crosslinking degree via the crosslinking time and temperature. The PEMs with the highest crosslinking degree showed better methanol rejection compared to the commercial benchmark. The introduction of the crosslinker created hydrophobic membrane sections, which reduced the water and methanol uptake. Subsequently, the membrane became denser due to the crosslinking, hindering the solute permeation. Those two effects led to lower methanol crossovers. This study proved the successful fabrication of PEMs overcoming the trade-off between proton conductivity and methanol rejection, following a facile procedure using low-cost and non-hazardous materials.

삼원계를 통한 페북소스타트 고체분산체 개발 및 평가

Febuxostat is classified as a biopharmaceutical with low solubility in aqueous solution and high intestinal permeability (Biopharmaceutics Classification System [BCS] Class II drug). The solubility of a drug has the characteristic of increasing as pH increases. This study aims to improve the dissolution of febuxostat with Neusilin® US2 and Gelucire®50/13 by a solvent evaporation method. The optimal formulation (solid dispersion, SD1) is developed as a solid dispersion of febuxostat : Gelucire®50/13 : US2®= 1:2:4 (w/w), with a final weight of 280 mg. The dissolution of SD1 in distilled water is 72.0±2.8%, which is 1.67-fold higher than that of the commercial product, Feburic Tab® (43.2±1.8%). The SD1 formulation is believed to have improved dissolution due to changes in physicochemical properties (thermal, interaction, and crystallinity). In conclusion, through the solid dispersion manufacturing method, febuxostat is changed from a crystalline form to an amorphous form in SD1 formulation, and the improved dissolution of febuxostat formulation is developed.