Polysulfone Hollow Fiber Research Articles

Numerical Simulation and Optimization of 4-Component LDG Separation in the Steelmaking Industry Using Polysulfone Hollow Fiber Membranes.

A general finite element model and a new solution method were developed to simulate the permeances of Lintz Donawiz converter gas (LDG) components and the performance of a polysulfone membrane separation unit. The permeances at eight bars of CO, N2, and H2 in LDG simulated using the developed model equations employing the experimental mixed gas data were obtained by controlling the finite element numbers and comparing them with pure gas permeation data. At the optimal finite element numbers (s = 15, n = 1), the gas permeances under the mixed-gas condition were 6.3% (CO), 3.9% (N2), and 7.2% (H2) larger than those of the pure gases, On the other hand, the mixed-gas permeance of CO2 was 4.5% smaller than that of pure gas. These differences were attributed to the plasticization phenomenon of the polysulfone membrane used by CO2. The newly adopted solution method for the stiff nonlinear model functions enabled the simulation of the performance (in terms of gas recovery, concentration, and flow rate) of the first-stage membrane within two seconds under most gas flow conditions. The performance of a first-stage membrane unit separating LDG could be predicted by the developed model with a small error of <2.1%. These model and solution methods could be utilized effectively for simulating gas permeances of the membrane that is plasticized severely by the permeating gas and the separation performance of two- or multi-stage membrane processes.

ELEVATED H2/N2 SEPARATION PERFORMANCE BY ANNEALING POST-TREATMENT OF POLYSULFONE HOLLOW FIBER MEMBRANE

This study aims to enhance the H2/N2 separation performance of polysulfone (PSF) hollow fiber membranes by annealing. X-ray diffraction, SEM, and FESEM were utilized to evaluate morphological and structural changes in denser annealed PSF membranes. AFM topography images were used to investigate the annealed form and roughness of PSF membranes. Before testing membrane permeation, it was annealed at 120, 150, and 190 °C to optimize gas separation performance. Compare to all annealing temperatures (120, 150, and 190 °C), the annealed PSF membrane at 150 °C had the greatest H2/N2 selectivity (16.18), but its separation performance was unsatisfactory since it was below the Robeson upper limit curve. The PSF before annealing and the PSF annealed at 190 °C showed outstanding separation performance (2.60 and 2.71, respectively), despite their lower selectivity than the PSF annealed at 150 °C

Modeling and Optimization of Spinning Parameters on Selectivity of Polysulfone Hollow Fiber Membrane for CO2/CH4 Separation

Hollow fiber membrane (HFM) and related technologies have recently become highly in demand and widely used in most industries and other areas recently. HFM could be used in different functions, from water and gas treatment to blood and medical applications. The paper describes the modeling of the effects of the spinning condition of a nonporous HFM on the membrane’s characteristics with the use of an automated hollow fiber fabrication system. An integrated, systematic experimental strategy based on the design of experiments was used to elaborate the effects of each parameter on selectivity. To obtain and sustain a satisfactory, significant selectivity of HFM, an automated system controlled the parameters during the fabrication process. The parameters involved in the fabrication of HFM and used in modeling are dope flow rate, bore flow rate, draw force, and air gap, which are considered inputs to fabricate polysulfone membrane. The fabrication process is improved by automating and instrumenting fabrication systems. An empirical model of the effects of fabrication parameters on the selectivity of the membrane is extracted experimentally. The mathematical model effectively explains the selectivity of CO2/CH4 with 95% fit.

Development of a Coating Method for Polydecylmethylsiloxane Selective Layer on Polysulfone Hollow Fiber Support

The paper presents a comparison of the techniques for polydecylmethylsiloxane selective layer coating to the inner and outer sides of a polysulfone hollow fiber support. It has been shown that coating to the outer side allows one to obtain a composite membrane with a higher selectivity for CO2/N2 vapor. A decrease in the number of defects in the selective layer is achieved by increasing the viscosity of the polydecylmethylsiloxane solution. The resulting membrane was characterized in the separation of a model mixture of hydrocarbons, and a high separation selectivity was shown - 12.4 with respect to the n-butane / methane gas pair.

Influence of Spinneret Dimensional Parameters on Gas Separation Properties of Polysulfone Hollow Fiber Membranes

The design and dimensional characteristics of the spinneret affect not only the geometry of the hollow fiber, but also the transport properties of the hollow fiber membranes. In the literature available today, there is a limited number of works in which the influence of the design and dimensional characteristics of the spinneret is studied. In this work, using the example of polysulfone hollow fiber membranes, it was shown that the use of a spinneret with smaller annular diameters leads to an increase in the gas permeability of the hollow fiber membrane with a decrease in the value of the ideal selectivity for the He/CO2 gas pair. It was found that using the spinneret with large annular diameters, the hollow fiber membrane is obtained with a smaller value of the average pore size of the flow, which is in agreement with the obtained data on gas permeability.

Original Installation for Researching the Process of Forming Polysulfone Hollow Fiber Membranes

In this work an original installation (manipulator) has been created that allows one to obtain up to 30 samples of hollow fiber membranes in one molding cycle, while simultaneously varying the molding conditions in a wide range (polymer concentration, nature of solvent and precipitant, exposure time in air and in a precipitant environment, post-processing and washing modes samples, diameter of the carrier needle). This installation makes it possible to move to a fundamentally higher level of accumulation of experimental data on the relationship "the composition of the spinning solution - the structure of the hollow fiber membrane - the separating properties of the membrane." It will also make it possible to involve in these studies new laboratory samples of polymers whose synthesis volumes are insufficient for the existing methods of obtaining laboratory samples of hollow fiber membranes. The principle of operation of the manipulator was worked out when obtaining mini-samples of hollow fiber PSF membranes from 24 wt. % PSF solution in NMP with the addition of 19 wt. % PEG-400 blowing agent on a carrier needle with external deposition. Mini-samples were obtained for studies of morphology, mechanical, transport and separation properties in one molding cycle of the manipulator. The properties of mini-samples of hollow fiber PSF membrane were compared with the properties of a membrane made by the method of “dry-wet” molding with internal deposition from a solution of the same composition. It was found that the porous structures of the membranes differ significantly from each other. In a hollow fiber PSF membrane obtained on a manipulator, the porous structure was spongy with separate macrovoids of various shapes. However, in the membrane obtained by the “dry-wet” method, a dense selective layer was formed on the inner side of the backing layer of elongated finger-shaped pores. It is the formation of spongy pores along the entire perimeter of the fiber wall that led to a decrease in the permeability of the hollow fiber PSF membrane obtained on the manipulator. Thus, not only the composition of the solution, but also the molding method makes a significant contribution to the properties of the membrane.

Enhanced adsorption and biocompatibility of polysulfone hollow fibre membrane via the addition of silica/alpha-mangostin hybrid nanoparticle for uremic toxins removal

In this study, a highly biocompatible adsorptive membrane is developed for haemodialysis application. Silica/α-mangostin hybrid nanoparticle was incorporated into polysulfone (PSf) based membrane to enhance the biocompatibility and the adsorption capacity of the membrane. The PSf based membranes were fabricated via dry-wet phase inversion technique and characterised based on scanning electron microscopy and contact angle measurement. The effects of silica/α-mangostin nanoparticle incorporation into PSf membrane were evaluated in terms of permeability, p-cresol adsorption capacity, urea, and creatinine removal capabilities, bovine serum albumin rejection and p-cresol dynamic adsorption. The biocompatibility assessment was done based on platelet adhesion, antioxidant properties, and complement activation of the membrane. The incorporation of the nanoparticle into PSf based membrane helped to smoothen the surface of the membrane and enhanced its hydrophilicity of the membrane by 12.54%. The presence of silica/α-mangostin in the membrane enhanced the adsorption capacity of the membrane by 20.92% with adsorption capacity of 55.64 mg/g at 500 mg/L initial concentration. The modified PSf membrane had also successfully improved the biocompatibility of the membrane by enhancing the scavenging activity of hydrogen peroxide and nitrogen oxide by 61.8% and 36%, respectively and inhibited the formation of C5a by 27.27%. The developed biocompatible PSf based adsorptive membrane has a good potential to be used for haemodialysis application.

Aβ Influx into the Blood Evoked by Different Blood Aβ Removal Systems: A Potential Therapy for Alzheimer's Disease.

PurposeAmyloid-β (Aβ) is a brain protein that causes Alzheimer’s disease. We have revealed that extracorporeal blood Aβ-removal systems evoked a large Aβ influx into the blood. This study investigated the system that is more effective in evoking Aβ influx.MethodsAβ removal activities were compared between hexadecyl-alkylated cellulose beads (HexDC) and fragments of polysulfone hollow fibers (PSf-HFs) in mini-columns to eliminate the filtration effect. Then, adsorptive filtration systems were adapted for PSf hemodialyzers to enhance Aβ adsorption on micropores in the wall of hollow fibers. Plasma Aβ concentrations of patients with renal failure were analyzed during treatment with PSf hemodialyzers alone for 8 h or tandemly connected HexDC and PSf hemodialyzers for 4 h.ResultsIn the in vitro study, Aβ removal efficiency for HexDC was approximately 100% during the 60 min treatment, whereas the removal efficiency for PSf-HF fragments gradually decreased. However, PSf hemodialyzer in adsorptive filtration systems removed Aβs comparably or more than HexDC. Aβ influx into the blood increases time-dependently. Concomitant use of HexDC and PSf hemodialyzer evoked a larger Aβ1–40 influx than that of PSf hemodialyzer alone. However, Aβ1–42 influx by PSf hemodialyzer alone was similar to or a little larger than influx by the combined system. Both systems evoked almost doubled Aβ influx than estimated Aβs existing in the normal brain during the 4 h treatment.ConclusionPSf hemodialyzer alone for a longer period and concomitant use of HexDC and PSf hemodialyzer for a shorter time effectively evoked a larger Aβ influx. To evoke Aβ1–42 influx, PSf hemodialyzer alone was effective enough. These findings of devices and treatment time may lead to optimal clinical settings for therapy and prevention of Alzheimer’s disease.

High flux polysulfone braided hollow fiber membrane for wastewater treatment role of zinc oxide as hydrophilic enhancer

Incorporation of zinc oxide (ZnO) nanoparticles has played an important role on the improvement of unique membrane characterization and performance, most notably the hydrophilic modification of the membrane for higher pure water permeability. Additionally, the permeability of the membrane can be improved via introduction of braid support by reducing the thickness of the membrane separation layer. Moreover, the braided hollow fiber membrane (BHFM) is able to perform under higher pressure conditions compared to hollow fiber membranes. In this paper, hybrid polysulfone (PSf)/ZnO BHFMs were fabricated via phase inversion method. Hydrophilic 10 ± 1.8 nm polycrystalline ZnO nanoparticles synthesized via sol-gel method were incorporated on BHFM to improve the hydrophilicity and increase flux with constant rejection under high pressure and the effect of the ZnO loading on the membrane properties and performance were thoroughly studied. The fabricated BHFMs with 0.0, 0.5, 1.0 and 1.5 wt% of ZnO nanoparticles concentration were defined as BHFM1, BHFM2, BHFM3 and BHFM4 respectively. Scanning electron microscopy (SEM), contact angle, mechanical strength, flux performance, rejection with bovine serum albumin (BSA) and fouling of best performed membrane were conducted to achieve the target of this paper. The performance of these hybrid ZnO/PSf BHFMs were compared with neat PSf hollow fiber membrane (HFM) and previous studies. The findings from this research work shows that BHFM4 has the most desired properties for wastewater treatment application. The ZnO nanoparticles in BHFM4 have improved hydrophilicity from 108.79° to 71.02°, and thus BHFM4 has increased flux performance from 36.20 to 919.12 L/m2 h at 1.0 bar pressure and 193.48 to 1909.11 L/m2h at 4.0 bar pressure when compared with BHFM1. Constant BSA rejection rates (> 90%) were observed in all BHFMs. The improved hydrophilicity and pure flux performance with constant rejection rate in high pressure conditions illustrates the suitability of fabricated ZnO/PSf BHFMs in wastewater treatment applications.

Two dimensional COFs as ultra-thin interlayer to build TFN hollow fiber nanofiltration membrane for desalination and heavy metal wastewater treatment

An ultra-thin interlayer of two-dimensional covalent organic frameworks (COFs) was in-situ formed on polysulfone hollow fiber (HF) substrate surface to manipulate the interfacial polymerization process for the construction of thin film nanocomposite (TFN) HF nanofiltration (NF) membrane with greatly improved separation performance. p-Phenylenediamine and 1,3,5-Triformylphloroglucinol monomers were used for constructing the COFs interlayer, piperazine and trimethyl chloride were used for the fabrication of the HF NF polyamide skin separation layer. A series of optimization of the membrane preparation conditions were carried out to achieve the good separation performance. The results demonstrated that the two-dimensional COFs nanomaterials could effectively control the pore size distribution and hydrophobicity of the HF substrate surface, realize a uniform distribution of piperazine on the interlayer surface, thus effectively manipulate the interfacial polymerization process. Under the optimal conditions, the rejections of Na2SO4, Cr2(SO4)3, CuSO4, ZnSO4 and MnSO4 can achieve 96.6 %, 95.4 %, 94.3 %, 91.7 % and 91.0 %, respectively, and the water permeance reaches 86.6 L m−2 h−1 MPa−1. Meanwhile, the fabricated TFN HF NF membrane shows good long-term stability, fouling resistance, acid and alkali resistance, as well as chlorine resistance, providing its vast potential for application in desalination and heavy metal wastewater treatment.

A cellular nitric oxide sensor based on porous hollow fiber with flow-through configuration

Nitric oxide plays important transmission and regulation roles in the human body, but its in-vitro concentration is extremely low with a short half-life. In this work, we developed a three-dimensional ‘flow-through’ configuration based on polysulfone hollow fiber (PHF) for efficient detection of cell released NO. The PHF served as the substrate for cell culture as well as the base layer of the working electrode. The carbon nanotubes-gold nanoparticles (CNT-AuNPs) composites uniformly wrapped around the PHF as the sensing layer. The CNT provided a large specific surface area, which allowed uniform distribution and high loading of AuNPs, thus enhancing the electrocatalytic activity synergistically. Compared with the conventional flow-by configuration, such configuration resulted in a higher surface area per unit volume and enhanced NO molecule capture efficiency. The CNT-AuNPs PHF sensor showed a low detection limit (91 nM), high stability, selectivity, and biocompatibility. We utilized it for real-time in-situ detection of NO released by human lung cancer cell H1299 under drug stimulation. Furthermore, owing to the unique PHF structure, we performed long-term monitoring of NO release under the treatment of Lipopolysaccharide, Nitroglycerin and Aminoguanidine, which helps to understand the kinetic process of cellular drug response.

Express Method of Preparation of Hollow Fiber Membrane Samples for Spinning Solution Optimization: Polysulfone as Example.

This article describes a new technique for the preparation of hollow fiber (HF) membrane samples using an automatic manipulator unit. The manipulator uses a syringe needle to form a HF of a given geometry. The needle in automatic mode is sequentially immersed, first into the polymer solution and then into the coagulation bath. The possibility of using a manipulator to obtain HF samples was studied on the known polysulfone (PSf)/N-methylpyrrolidone (NMP)/pore-forming additive system. A series of HF membrane samples were made within 29 h from twelve 1 mL PSf casting solutions. This was 15 times faster than obtaining samples of HF membranes at the multifunctional research laboratory facility. From the point of view of the consumption of the components of the casting solution, the use of the manipulator was 30 times more economical, and the consumption of water for precipitation and washing was 8000 times less. The developed method made it possible to study samples of HF by scanning electron microscopy (SEM), ultrafiltration, and evaluate its mechanical properties without spinning the membranes. Using the new technique, the optimal composition of the casting solution for the wet spinning of HF PSf membranes was selected during two weeks. Thus, the manipulator makes it possible to significantly reduce the time of the new membrane preparation, reduce the volume of used polymer, and thus makes it promising to study expensive or new membrane materials.

Formation of Polysulfone Hollow Fiber Membranes Using the Systems with Lower Critical Solution Temperature

This study deals with the investigation of the phase state of the polymer systems from polysulfone (PSF) with the addition of polyethylene glycol (PEG-400, Mn = 400 g·mol−1) and polyvinylpyrrolidone (PVP K-30, Mn = 40,000 g·mol−1) in N,N-dimethylacetamide (DMA), which feature lower critical solution temperatures (LCSTs). A fragment of the phase state diagram of the system PSF —PEG-400—PVP K-30—DMA was experimentally constructed in the following range of component concentrations: PSF 20–24 wt.%, PEG-400—35–38 wt.% and PVP—0–8 wt.%. It has been established that PVP addition substantially reduces the phase separation temperature down to 50–60 °C. Based on the obtained phase diagrams, a method for preparation of highly permeable hollow fiber membranes from PSF, which involves the processing of the dope solution at a temperature close to the LCST and the temperature of the bore fluid above the LCST, was proposed. Hollow fiber membranes with pure water flux of 1200 L·m−2·h−1 and a sponge-like macrovoid-free structure were obtained via LCST-thermally induced phase separation by free fall spinning technique.

Extraction of La(III) by a nonionic microemulsion containing D2EHPA in hollow fiber contactor

This study aimed to prepare a W/O nonionic microemulsion system(MEs) consisting of OP-4[polyoxyethylene(4) nonylphenol], OP-7[polyoxyethylene(7) nonylphenol], 1-hexanol, D2EHPA, kerosene and HCl solution and applied to the extraction of La(III) from chloride aqueous solution within the polysulfone hollow fiber contactor (HFC),laboratory-scale experiments were carried out to investigate the recovery of La(III) using as-prepared microemulsion from the simulation wastewater containing La(III),Al(III) and Fe(III). The right weight ratio(Rs) of OP-4 to OP-7 was firstly confirmed through determination of the solubilization capacity of HCl solution(W0,HCl) in microemulsion, the effect of several factors such as the HCl concentration, temperature and effective extraction time on the extraction efficiency of La(III) was discussed. Results showed that the acceptable Rs was 4:6 to prepare the W/O MEs. The extraction yield of La(III) increased with the increasing of HCl concentration, temperature and effective extraction time and reaches to 97.3% while using five-stage modules. The recovery yield of La(III) from simulation La-bearing wastewater was 90.6%.

Polyamide-MIL-101(Cr) Thin Films Synthesized on Either the Outer or Inner Surfaces of a Polysulfone Hollow Fiber for Water Nanofiltration.

High-performance thin film nanocomposite (TFN) hollow fiber (HF) membranes, with MIL-101(Cr) MOF nanoparticles (52 ± 13 nm) embedded, have been synthesized with the polyamide layer formed either on the outer or inner surface of a polysulfone HF (250 and 380 μm ID and OD, respectively). The TFN_out membrane was developed using the conventional interfacial polymerization method, typically applied to obtain TFN flat membranes (MOF particles added to the thin layer by deposition). This membrane gave a water permeance value of 1.0 ± 0.7 L·m–2·h–1·bar–1 and a rejection of 90.9 ± 1.2% of acridine orange (AO, 265 Da). In contrast, the TFN_in membrane was synthesized by microfluidic means and gave a significantly higher water permeance of 2.8 ± 0.2 L·m–2·h–1·bar–1 and a slightly lower rejection of 87.4 ± 2.5% of the same solute. This remarkable increase of flux obtained with small solute AO suggests that the HF membranes developed in this work would exhibit good performance with other typical solutes with higher molecular weight than AO. The differences between the performances of both TFN_in and TFN_out membranes lay on the distinct superficial physicochemical properties of the support, the synthesis method, and the different concentrations of MOF present in the polyamide films of both membranes. The TFN_in is more desirable due to its potential advantages, and more effortless scalability due to the microfluidic continuous synthesis. In addition, the TFN_in membrane needs much fewer quantities of reactants to be synthesized than the TFN_out or the flat membrane version.

CO2/CH4 mixed gas separation using graphene oxide nanosheets embedded hollow fiber membranes: Evaluating effect of filler concentration on performance

Graphene oxide (GO) nanosheets-based composite polymeric membranes are being explored for the effective separation of gases owing to hydrophilic nature and abundant oxygen moieties on their surface that attracts the polar gases. In this study, the effect of GO nanosheets concentration on the CO2/CH4 mixed gas separation performance of polysulfone (Psf) hollow fiber mixed matrix membranes (HFMMMs) was examined. The different concentration of GO, i.e., 0.25, 0.5, and 0.75 wt% of the polymer dope solution, was used. Hollow fiber membranes (HFMs) were prepared using dry/wet quench method with water as non-solvent, and physicochemical properties were evaluated. Morphological changes were observed in the Psf/GO HFMMMs. The gas separation performance study of the HFM samples was carried out using pure CO2 and CH4 gases at 1–5 bar transmembrane pressure and 25 ± 2 °C. It was found that HFMMMs with 0.25 wt% GO nanosheets (PG25) showed 137% higher ideal CO2/CH4 selectivity than the pristine HFMs. In case of the mixed gas permeation studies using feed consisting of 50:50 vol% of CO2 and CH4, the PG25 HFMMMs showed 201% higher CO2/CH4 selectivity than that of the pristine HFMs. Moreover, the PG25 HFMMMs showed separation performance stability when they were applied for the long-term stability study. These results indicate that 0.25 wt% GO nanosheets in Psf is the optimum concentration which gives improved CO2/CH4 mixed gas separation performance.

A new perspective of functionalized MWCNT incorporated thin film nanocomposite hollow fiber membranes for the separation of various gases

As the increasing demand for gas separation technologies in the industry, the polymeric membrane separation technology has received wide attention based on the advantages of high gas permeance, and low cost. Thin film nanocomposite (TFN) membranes used for the gas separation in industrial level is one of the best choices, because of applied nanoparticles synergistic properties influence to enhance gas permeance and selectivity. In this study thin selective nanocomposite layer has been developed using interfacial polymerization between 3,5-diaminobenzoic acid (DABA) with carboxylated multi-walled carbon nanotubes (C-MWCNTs) and trimesoyl chloride (TMC) on the surface of polysulfone hollow fiber substrate for the separation of various gases like water vapor, H2, CO2, CH4 and N2. Different concentrations of C-MWCNTs are used for the preparation of various TFN membranes. All prepared TFN membranes were well characterized using different physiochemical characterization techniques like ATR-FTIR, AFM, SEM, XPS, contact angle etc. It is found that the prepared membranes are not only used for the separation of water vapor but also utilize for the separation of different gases like H2, CO2, CH4, and N2. The TFN hollow fiber membranes prepared with 0.04 % C-MWCNTs, (C-MWCNT@DT-M4) show good performance in the form of permeance and selectivity among all the prepared membranes, as a water vapor permeance 2570 GPU, H2 permeance 92.5 GPU, along with the water vapor/N2 641, H2/CO2 4.41 and CO2/N2 24.74 and CO2/CH4 18.45 selectivities respectively. The prepared TFN membranes show superior performance to C-MWCNT-based membranes because of their synergetic bonding chemistry and hydrophilic nature. This study has proven that slight addition of functional MWCNTs in polymeric nanocomposite membranes responsible to obtain better performance of the TFN membranes.

Impacts of Multilayer Hybrid Coating on PSF Hollow Fiber Membrane for Enhanced Gas Separation.

One of the most critical issues encountered by polymeric membranes for the gas separation process is the trade-off effect between gas permeability and selectivity. The aim of this work is to develop a simple yet effective coating technique to modify the surface properties of commonly used polysulfone (PSF) hollow fiber membranes to address the trade-off effect for CO2/CH4 and O2/N2 separation. In this study, multilayer coated PSF hollow fibers were fabricated by incorporating a graphene oxide (GO) nanosheet into the selective coating layer made of polyether block amide (Pebax). In order to prevent the penetration of Pebax coating solution into the membrane substrate, a gutter layer of polydimethylsiloxane (PDMS) was formed between the substrate and Pebax layer. The impacts of GO loadings (0.0–1.0 wt%) on the Pebax layer properties and the membrane performances were then investigated. XPS data clearly showed the existence of GO in the membrane selective layer, and the higher the amount of GO incorporated the greater the sp2 hybridization state of carbon detected. In terms of coating layer morphology, increasing the GO amount only affected the membrane surface roughness without altering the entire coating layer thickness. Our findings indicated that the addition of 0.8 wt% GO into the Pebax coating layer could produce the best performing multilayer coated membrane, showing 56.1% and 20.9% enhancements in the CO2/CH4 and O2/N2 gas pair selectivities, respectively, in comparison to the membrane without GO incorporation. The improvement is due to the increased tortuous path in the selective layer, which created a higher resistance to the larger gas molecules (CH4 and N2) compared to the smaller gas molecules (CO2 and O2). The best performing membrane also demonstrated a lower degree of plasticization and a very stable performance over the entire 50-h operation, recording CO2/CH4 and O2/N2 gas pair selectivities of 52.57 (CO2 permeance: 28.08 GPU) and 8.05 (O2 permeance: 5.32 GPU), respectively.

Effect of Draw Ratio on the Morphology of Polysulfone Hollow Fiber Membranes

The draw ratio (DR) is an important parameter in the process of spinning hollow fiber membranes, by which their separation and performance characteristics can be controlled over a wide range of values. For the first time, a method for determining the DR using a roller movable in the vertical direction is described, which makes it possible to establish the ratio of the dope extrusion linear flow rate to the take-up speed. In the course of the work, polysulfone hollow-fiber membranes were obtained at various DR values. The influence of the draw ratio on the morphology and geometric and gas transport properties of the resulting polysulfone hollow fiber membranes has been examined.

Capillary-driven blood separation and in-situ electrochemical detection based on 3D conductive gradient hollow fiber membrane

It is essential to develop portable, versatile, and reliable diagnostic devices in point-of-care testing (POCT). The detection of biomarkers requires selective separation and large specific surface for high sensitivity and accuracy at trace levels in whole blood samples using POCT devices. Herein, a kind of 3D electrochemical biosensors were designed via in-situ synthesizing polyaniline (PANI) and platinum nanoparticles (Pt NPs) on polysulfone hollow fiber membrane (HFM) scaffolds with gradient porous structure. The gradient porous HFMs scaffolds provide uniform capillary flow, self-driven blood separation and sufficient enzyme immobilization sites. Simultaneously, the in-situ deposited materials fulfill interconnected conductive networks, thus ensuring accurate and rapid detection of the sensors without hindering capillary progress. These sensors display ultralow sampling (~3 μL), fast fluid flow (>1 μL/ms), wide linear range (glucose: 0–24 mM, R2=0.992; cholesterol: 0–9 mM, R2=0.999), high sensitivity and accuracy especially under different hematocrits in POCT applications towards glucose and cholesterol. The innovative integration of POCT biosensors with interconnected conductive nanoparticles, selective blood separation and gradient porous structures can find wide application in resource-limited regions, large population screening, and public health emergencies.