Porous Polytetrafluoroethylene Membrane Research Articles

Superwetting membrane-based strategy for highly efficient separation of dimethyl carbonate and methanol

Dimethyl carbonate (DMC) produced through transesterification, which involves the reaction of methanol (MeOH) with a suitable ester, has been considered as an attractive route for industrial production. Although high-purity DMC can be obtained from DMC/MeOH mixture by energy-intensive extractive distillation or time-consuming pervaporation (PV), it is still challenging to produce pure DMC in an energy-saving and high-efficiency manner. Here we demonstrate an energy-economy yet efficient superwetting membrane (SWM)-based strategy to produce pure DMC by combining porous polytetrafluoroethylene (PTFE) as the solid membrane and eco-friendly water molecules as the liquid inductive agent. The relatively low polar DMC can rapidly and selectively permeate the nonpolar PTFE membrane by nonpolar interaction between PTFE and DMC. Meanwhile, the high polar water molecules generate strong hydration with MeOH, which makes the relatively high polar MeOH/H2O being blocked by the nonpolar PTFE membrane. The SWM system exhibits outstanding separation flux of 1090 L m−2 h−1, with DMC purity higher than 93 wt%. Furthermore, taking advantage of the easy assembly of this SWM with conventional PV, we can produce DMC with purity of 99.4 wt%, showing great potential in practical DMC production.

Quantitative Analysis of CO2 Evolution in an Alkaline Electrolyte Solution By Differential Electrochemical Mass Spectroscopy

CO2 is involved in various main and side reactions of electrochemical energy devices, such as carbon corrosion reactions and alcohol oxidation reactions. Differential electrochemical mass spectroscopy (DEMS) has been intensively applied in acidic electrolyte solutions to analyze these reactions. DEMS is the in-situ electrochemical measurement technique to analyze volatile species with the mass spectrometer (MS). However, the applications of DEMS to alkaline electrolyte solutions have been limited due to the high solubility of CO2 in alkaline solutions. While "conventional DEMS cells," where porous thin-film working electrodes are formed onto polytetrafluoroethylene (PTFE) membrane interface, can quantitatively analyze CO2 that has not dissolved into the electrolyte yet [1], the working electrode materials are limited to those that can be deposited on porous PTFE membrane as porous thin-films. Recently, Möller et al. have developed the DEMS system, which can detect CO2 from general planer electrodes coated by catalyst powders by combining a neutralizer and "dual thin-layer flow cell" [2]. However, due to the relatively low detection limit, quantitative analysis of evolved CO2 has not been accomplished. In this study, we attempt to use high surface area electrodes to enhance the MS signal of CO2 to enable quantitative analysis of evolved CO2. To suppress the in-plane reaction distribution in the flow cell, we integrated an anion exchange membrane into the cell and arranged the counter electrode opposing the working electrode [3] (Fig. 1 (a)).CO-stripping voltammetry was performed to evaluate the CO2 detectability of the constructed DEMS system. The DEMS cell was composed of a commercial Pt/C electrode as the working electrode, a commercial Hg/HgO electrode as the reference electrode, a Pt mesh as the reference electrode, 1 mol dm–3 KOH aq as the electrolyte solution, and 1 mol dm–3 H2SO4 aq as the neutralizer. Figure 1 (b) shows the CO-stripping voltammogram and corresponding MS signal of CO2 (m/z = 44). MS signal of CO2 accompanied by the anodic CO oxidation current is clearly observed from 0.6 to 1.2 V vs. RHE. The calibration constant, which correlates the MS signal of CO2 to partial current for CO2 evolution reaction, is successfully obtained as 2.2 × 10–10, which shows that the DEMS system established in this study can quantitatively analyze CO2. Applications to the carbon corrosion reactions are also presented at the site.

Janus membranes with simultaneous flux enhancement and fouling/wetting resistance prepared by a modified interfacial polymerization process for membrane distillation

Conventional membrane distillation (MD) membranes are hydrophobic and challenged by severe membrane fouling and wetting. Current surface modification strategies for anti-fouling and anti-wetting purposes, usually complex and time-consuming, often compromise the MD flux. Herein, we propose a modified interfacial polymerization (mIP) approach to fabricate Janus membranes with rapid and robust MD performance. In the mIP process, a dry hydrophobic substrate is first immersed in an oil-phase monomer solution and then in contact with an aqueous monomer solution to trigger the mIP reaction. The as-fabricated Janus membrane (e.g., IP2@PTFE) comprised an ultrathin, underwater oleophobic, and defect-free polyamide (PA) layer and a porous polytetrafluoroethylene (PTFE) substrate. Compared with the unmodified PTFE membrane, the vacuum MD flux of the IP2@PTFE membrane held a 177.4 % increase when tackling a NaCl solution (3.5 wt%) at 60 °C. When the NaCl solution contained sodium dodecyl sulfate (SDS) surfactant or/and mineral oil, the IP2@PTFE membrane exhibited fouling and wetting resistance simultaneously; conversely, severe oil fouling and quick SDS-induced wetting occurred on the pristine PTFE membrane. The mIP process does not require any pretreatment of the hydrophobic substrate, so it is facile and scalable. We believe that this study will facilitate the design of robust MD membranes.

Miniaturized liquid extraction cartridge with a functional porous polytetrafluoroethylene membrane for the determination of formaldehyde in gaseous samples

Miniaturized liquid extraction cartridge with a functional porous polytetrafluoroethylene membrane for the determination of formaldehyde in gaseous samples

Miniaturized liquid extraction cartridge with a functional porous polytetrafluoroethylene membrane for the determination of formaldehyde in gaseous samples

AbstractA new miniaturized liquid extraction cartridge equipped with a functional porous polytetrafluoroethylene membrane was developed for the determination of formaldehyde in gaseous samples. The functional polytetrafluoroethylene membrane allows gas to pass through while repelling both water‐based and organic‐based liquids. A derivatization reagent for formaldehyde, 2,4‐dinitrophenylhydrazine, was placed in the cartridge and gaseous samples are collected through the cartridge at 20 ml/min for 30 min. Formaldehyde in the gaseous sample is captured as the corresponding 2,4‐dinitrophenylhydrazine hydrazone, and an aliquot of the sample collection solution can be directly subjected to high‐performance liquid chromatographic analysis. The limit of quantification for the developed method was 5 ng/L formaldehyde in gas with a sampling volume of 600 ml. Proof‐of‐concept for formaldehyde determination in an aqueous sample was demonstrated using the developed cartridge in a purge‐and‐trap extraction setup.

Effect of heat treatments and aggressive media on mechanical properties of porous polytetrafluoroethylene membranes fabricated via electrospinning

Electrospinning is a modern alternative to the expanded method for producing porous polytetrafluoroethylene membranes. High strength and relative elongation, as well as the ability to maintain these properties for a long time when exposed to aggressive media at high temperatures, determine the application scope of the electrospun polytetrafluoroethylene membranes. Herein, we report the effect of Polytetrafluoroethylene/Polyvinyl alcohol ratio in the electrospinning solution, heat treatment mode (quenching and annealing) and aggressive media at high temperatures on the shrinkage, tensile strength and relative elongation of electrospun polytetrafluoroethylene membranes. We found that decreased Polytetrafluoroethylene/Polyvinyl alcohol ratio in the electrospinning solution increases shrinkage, but improves tensile strength and relative elongation of polytetrafluoroethylene membranes. Quenching of membranes after heating is a more preferable treatment option than annealing as it allows to obtain the membrane with less shrinkage and better mechanical properties. Exposure of electrospun polytetrafluoroethylene membranes to concentrated mineral acids and alkalis, a bipolar aprotic solvent, engine oil and deionized water at 100 °C for 48 h did not deteriorate their tensile strength and relative elongation.

Thin-Film Composite Membranes with a Carbon Nanotube Interlayer for Organic Solvent Nanofiltration.

Compared to the traditional chemical-crosslinking-based polymer, the porous polytetrafluoroethylene (PTFE) substrate is considered to be an excellent support for the fabrication of thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes. However, the low surface energy and chemical inertness of PTFE membranes presented major challenges for fabricating a polyamide active layer on its surface via interfacial polymerization (IP). In this study, a triple-layered TFC OSN membrane was fabricated via IP, which consisted of a PA top layer on a carbon nanotube (CNT) interlayer covering the macroporous PTFE substrate. The defect-free formation and cross-linking degree of the PA layer can be improved by controlling the CNT deposition amount to achieve a good OSN performance. This new TFC OSN membrane exhibited a high dye rejection (the rejection of Bright blue B > 97%) and a moderate and stable methanol permeated flux of approximately 8.0 L m−2 h−1 bar−1. Moreover, this TFC OSN membrane also exhibited an excellent solvent resistance to various organic solvents and long-term stability during a continuous OSN process.

Speciation of inorganic arsenic in aqueous samples using a novel hydride generation microfluidic paper-based analytical device (µPAD)

The development of the first microfluidic paper-based analytical device (µPAD) for the speciation of inorganic arsenic in environmental aqueous samples as arsenite (As(III)) and arsenate (As(V)) which implements hydride generation on a paper platform is described. The newly developed µPAD has a 3D configuration and uses Au(III) chloride as the detection reagent. Sodium borohydride is used to generate arsine in the device’s sample zone by reducing As(III) in the presence of hydrochloric acid or both As(III) and As(V) (total inorganic As) in the presence of sulfuric acid. Arsine then diffuses across a hydrophobic porous polytetrafluoroethylene membrane into the device’s detection zone where it reduces Au(III) to Au nanoparticles. This results in a color change which can be related to the concentration of As(III) or total inorganic As (i.e., As(III) and As(V)) concentration. Under optimal conditions, the µPAD is characterized by a limit of detection of 0.43 mg L−1 for total inorganic As (As(III) + As(V)) and 0.41 mg L−1 for As(III) and a linear calibration range in both cases of 1.2–8.0 mg As L−1. The newly developed µPAD-based method was validated by applying it to groundwater and freshwater samples and comparing the results with those obtained by conventional atomic spectrometric techniques.Graphical abstract

Selectivity of vacuum ammonia stripping using porous gas-permeable and dense pervaporation membranes under various hydraulic conditions and feed water compositions

Recovery of ammonia (NH3) from residual waters offers various reuse opportunities, such as the production of fertilisers and the generation of electricity and heat. However, simultaneous evaporation of water (H2O) during NH3 stripping under vacuum results in diluted recovered NH3 gas with high H2O contents. Whereas porous gas-permeable membranes are already used for vacuum NH3 stripping, the use of non-porous silica-based pervaporation (PV) membranes showed promising results in recent literature, with respect to more selective transfer of NH3 compared to H2O. In this study, we assessed the selectivity of NH3 over H2O transfer (SNH3/H2O) for different types of membranes, under various hydraulic conditions and feed water compositions. The three following membranes were tested: a porous gas-permeable polytetrafluoroethylene (PTFE) membrane, a hydrophilic (Hybrid Silica PV) membrane and a hydrophobic polydimethylsiloxane PV (PDMS PV) membrane.For the PTFE and the Hybrid Silica PV membrane, SNH3/H2O ranged between 0.1 and 0.4, indicating that the transfer of NH3 was consistently less preferred compared to the transfer of H2O. The preference for H2O over NH3 transfer through the membranes at various hydraulic conditions and feed water compositions can be assigned to the similarity in polarity and kinetic diameter of NH3 and H2O and the low relative concentration of NH3 in the used feed waters (approximately 0.1–1.0 wt%). The PDMS PV membrane showed negligible NH3 transfer and deteriorated rapidly during the NH3 stripping experiments. The SNH3/H2O of both gas-permeable and PV membranes was higher for unsteady than for steady hydraulic conditions. Furthermore, the SNH3/H2O of the both PTFE and the Hybrid Silica decreased when the ionic strength of the feed water increased from 0.0 to 0.8 mol∙L−1 and when the NH3 feed water concentration increased from 1 to 10 g∙L−1. According to the results, the used PV membranes did not show selectivity of NH3 over H2O transfer. In fact, the used PV membranes consistently had a lower SNH3/H2O than the PTFE membrane. Hence, the dense silica-based PV membranes did not allow for the recovery of gaseous NH3 from water, with lower H2O content in the recovered gas, compared to porous PTFE membranes.

A rapid hydrophilization of porous poly(tetrafluoroethylene) film via co-deposition of phenol derivatives and polyethyleneimine

A series of hydrophilized porous polytetrafluoroethylene (PTFE) membranes were prepared by a mussel-inspired coating method. Various types of phenol derivatives possessing different number of hydroxide groups at different position such as hydroquinone, pyrogallol, hydroxyhydroquinone were applied along with polyethyleneimine (PEI) to seek for the fast and stable surface modification. The co-deposition kinetics of phenol/PEI pair on the porous PTFE membranes was examined using the ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Surface morphology and pore diameter were analyzed by the field emission scanning electron microscopy and mercury porosimetry. To confirm the complete surface hydrophilicity, water contact angle was measured as a function of time for different co-deposition pairs. Among several phenol derivatives paired with PEI, hydroxyhydroquinone showed the fastest deposition rate (in about 40 min) for excellent hydrophilicity and stability. The chemical modification method applied in this study showed the long-term stability in commonly used and harsh solvents including acidic and basic solutions compared to the other physical and chemical methods previously reported.

Characterization and Determination of the Biocompatibility of Porous Polytetrafluoroethylene Membranes Fabricated via Electrospinning

The structure and properties of polytetrafluoroethylene (PTFE) polymeric membranes obtained by electrospinning from a suspension of PTFE in a solution of polyvinyl alcohol (PVA) with subsequent thermal treatment were presented. The effect of the PTFE suspension ratio in spinning solutions on the morphology, crystal structure, chemical composition, strength, and cytotoxicity of the formed PTFE membranes was evaluated. We found that a decrease in the PTFE suspension content in spinning solutions leads to a decrease in the number of defects in the membrane fibers, which increasing the strength and elongation. Membranes made from spinning solutions with a lower content of PTFE suspension have a higher degree of crystallinity and a more perfect crystal structure. It has been suggested that the products of PVA destruction during the heat treatment of PTFE/PVA membranes are capable of plasticizing effects on PTFE particles, improving the strength of PTFE membranes. The membranes after thermal treatment were not cytotoxic regardless of the PTFE suspension content in the spinning solutions. High biocompatibility of membranes was established during implantation into soft tissues.

Operating characteristics of a dual flat-evaporator loop heat pipe for single heat source cooling in any orientation

This paper reports the operating characteristics of a dual flat-evaporator loop heat pipe (LHP) for single heat source cooling in any orientation. The performance of the dual flat-evaporator LHP is compared with that of other single evaporator LHPs used in various orientations. An LHP with two flat evaporators and one natural convection condenser was designed and produced. Capillary structures were made from hydrophilic polytetrafluoroethylene porous membranes, and pure water was used as the working fluid. Two flat evaporators were set on opposite sides of a heat source to maintain the heat source temperature below 130 °C in six typical orientations. Evaporators/compensation chambers (CC) ran parallel to the horizontal plane, in which one evaporator was located completely above its CC, in two orientations. Evaporators/CCs were parallel to the vertical plane in the other orientations. The LHP successfully operated with normal operating patterns in all orientations. In the first two orientations, the unsaturated CC was the lower CC, and was flooded by liquid (deeply subcooled state) owing to gravity. The unsaturated CC contained both vapor and liquid in the other four orientations. In addition to the difference in elevation between the evaporators and condenser, this was the main reason for the difference in LHP operating characteristics in the six orientations. However, LHP performance was relatively uniform at each heat load when LHP orientation changed. The steady-state temperature could be estimated using our proposed numerical model. Below the heat source temperature of 130 °C, 140-W heat was transported and cooled with the lowest thermal resistance of 0.34 K/W.

Efficient Portable Urea Biosensor Based on Urease Immobilized Membrane for Monitoring of Physiological Fluids.

Numerous studies have addressed the utilization of glutaraldehyde (GA) as a homobifunctional cross-linker. However, its applicability has been impeded due to several issues, including the tendency of GA molecules to undergo polymerization. Herein, a portable urea biosensor was developed for the real-time monitoring of the flow of physiological fluids; this was achieved by using disuccinimidyl cross-linker-based urease immobilization. Urease was immobilized on a porous polytetrafluoroethylene (PTFE) solid support using different disuccinimidyl cross-linkers, namely disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS) and bis-N-succinimidyl-(pentaethylene glycol) ester (BS(PEG)5). A urease activity test revealed that DSS exhibited the highest urease immobilizing efficiency, whereas FT-IR analysis confirmed that urease was immobilized on the PTFE membrane via DSS cross-linking. The membrane was inserted in a polydimethylsiloxane (PDMS) fluidic chamber that generated an electrochemical signal in the presence of a flowing fluid containing urea. Urea samples were allowed to flow into the urea biosensor (1.0 mL/min) and the signal was measured using chronoamperometry. The sensitivity of the DSS urea biosensor was the highest of all the trialed biosensors and was found to be superior to the more commonly used GA cross-linker. To simulate real-time monitoring in a human patient, flowing urea-spiked human serum was measured and the effective urease immobilization of the DSS urea biosensor was confirmed. The repeatability and interference of the urea biosensor were suitable for monitoring urea concentrations typically found in human patients.

Phosphine Electrochemical Sensor Using Gold-Deposited Polytetrafluoroethylene Membrane.

Phosphine gas is a toxic and flammable gas, which are useful dopant in the semiconducting industry. OSAH (Occupational Safety and Health Administration) regulates the threshold limit value as 0.3 ppm. To detect phosphine gas, an electrochemical sensor cell using gold as a working electrode is available. In this paper, we prepared Au thin film electrode on porous PTFE (polytetrafluoroethylene) membrane by using d.c. sputtering machine. Au thin film deposited on PTFE membrane for 300 s showed the thickness about 220 nm and electrical resistance between 5 and 10 ohm. We adopted this Au thin film as a working electrode and reference electrode. The sensitivity of the electrochemical cell is about 3000 nA/ppm for phosphine gas. Using Cottrell equation and COMSOL program, we simulated the diffusion coefficient of phosphine gas within the electrochemical cell, which showed the value of 1.21×10-7 m²/s.

Ultra-low vanadium ion permeable electrolyte membrane for vanadium redox flow battery by pore filling of PTFE substrate

The proton conductive membranes were prepared by impregnating sulfonated poly(arylene ether ketone) (SP) into the porous polytetrafluoroethylene (PTFE) substrates for vanadium redox flow battery application. To impregnate SP, the surface of porous PTFE was chemically hydrophilized with catechol and polyethyleneimine (PEI). The SP filled PTFE membranes (trPTFE/SP) showed significantly enhanced thermal, dimensional, and mechanical stability, compared with the pristine SP membranes. While the water uptake of trPTFE/SP membranes reduced by only 3–5%, the swelling ratio reduced to about a half and tensile strength increased by 5 times. Although this pore filling process slightly decreased the proton conductivity of the pure SP membranes by 10%, it hugely decreased the vanadium ion permeability about 5 times. Their low vanadium permeability, 1.37 ​× ​10−7 ​cm2 ​min−1–4.21 ​× ​10−7 ​cm2 ​min−1, was even 15 times at most lower than that of Nafion117, 20.28 ​× ​10−7 ​cm2 ​min−1. This low vanadium permeability led to high coulombic efficiency over 96% and energy efficiency around 84% during the 100 charge-discharge cycling tests, which are better than Nafion117 membrane.

Engineering hierarchically structured superhydrophobic PTFE/POSS nanofibrous membranes for membrane distillation

Membrane distillation (MD) is an attractive thermally-driven membrane process for desalination, brine and wastewater treatment. One of the main obstacles impeding MD application is the absence of effective MD membranes with sufficient water permeability and long-term stability. Attributed to the outstanding hydrophobicity, excellent thermal and chemical resistance, the most ideal polymer to develop MD membrane is polytetrafluoroethylene (PTFE). However, the fabrication of PTFE membranes is challenging due to its poor processability. This work describes a novel strategy to develop superhydrophobic and highly porous PTFE membranes via electrospinning. The hydrophobic nanoparticles 8 vinyl-grafted polyhedral oligosilicone (vinyl-POSS) were firstly incorporated into PTFE nanofibers to promote the crystallization of PTFE nanofiber, enhance nanofiber roughness, and improve membrane mechanical robustness and porosity. The effects of vinyl-POSS concentration, temperature and salt concentration of feed solutions on MD performance of PTFE/POSS nanofibrous membranes were investigated systemically in this study. The optimized PTFE/POSS nanofibrous membrane #POSS-2 has a three-dimensional (3D) superhydrophobic property with a water contact angle of 151 ± 4°. It exhibited a competitive water flux of 40 ± 2 Lm−2 h−1 in the direct contact membrane distillation (DCMD) process when the feed and permeate temperatures were 60 and 20 °C, respectively. Moreover, #POSS-2 possessed an excellent long-term stability in a 200-h continuous DCMD operation.

Enhancement of Flux Performance in PTFE Membranes for Direct Contact Membrane Distillation.

This work focused on enhancing the flux on hydrophobic polymeric membranes aimed for direct contact membrane distillation desalination (DCMD) process without compromising salt rejection efficiency. Successful coating of commercial porous poly-tetrafluoroethylene membranes with poly(vinyl alcohol) (PVA) was achieved by solution dipping followed by a cross-linking step. The modified membranes were evaluated for their performance in DCMD, in terms of water flux and salt rejection. A series of different PVA concentration dipping solutions were used, and the results indicated that there was an optimum concentration after which the membranes became hydrophilic and unsuitable for use in membrane distillation. Best performing membranes were achieved under the specific experimental conditions, water flux 12.2 L·m-2·h-1 [LMH] with a salt rejection of 99.9%. Compared to the pristine membrane, the flux was enhanced by a factor of 2.7. The results seemed to indicate that introducing hydrophilic characteristics in a certain amount to a hydrophobic membrane could significantly enhance the membrane distillation (MD) performance without compromising salt rejection.

Nonwoven PTFE Membranes Fabricated by Electrospinning Method: Preparation and Characterization

Polytetrafluoroethylene (PTFE) is one of the promising materials for the purposes of tissue engineering and chemical technology because of its excellent physico-chemical properties and mechanical characteristics. However, conventional methods of PTFE porous membranes production have several disadvantages which limit the number of potential application areas by reason of a insufficient surface-to-volume ratio and poor porosity at small thickness. In the paper the results of using PTFE water suspension with a solution of water-soluble polymer for preparation of porous membranes by electrospinning are reported. The physico-chemical characteristics of membranes were investigated depending on the content of PTFE dispersion in spinning solution. There were found high hydrophobicity and lyophilicity of PTFE electrospun membranes. Main reasons of poor mechanical properties of porous membranes at high content of PTFE suspension in spinning solution are discovered. The ways of mechanical properties improvement and areas of possible applications are proposed.

Parylene-Coated Polytetrafluoroethylene-Membrane-Based Portable Urea Sensor for Real-Time Monitoring of Urea in Peritoneal Dialysate.

A portable urea sensor for use in fast flow conditions was fabricated using porous polytetrafluoroethylene (PTFE) membranes coated with amine-functionalized parylene, parylene-A, by vapor deposition. The urea-hydrolyzing enzyme urease was immobilized on the parylene-A-coated PTFE membranes using glutaraldehyde. The urease-immobilized membranes were assembled in a polydimethylsiloxane (PDMS) fluidic chamber, and a screen-printed carbon three-electrode system was used for electrochemical measurements. The success of urease immobilization was confirmed using scanning electron microscopy, and fourier-transform infrared spectroscopy. The optimum concentration of urease for immobilization on the parylene-A-coated PTFE membranes was determined to be 48 mg/mL, and the optimum number of membranes in the PDMS chamber was found to be eight. Using these optimized conditions, we fabricated the urea biosensor and monitored urea samples under various flow rates ranging from 0.5 to 10 mL/min in the flow condition using chronoamperometry. To test the applicability of the sensor for physiological samples, we used it for monitoring urea concentration in the waste peritoneal dialysate of a patient with chronic renal failure, at a flow rate of 0.5 mL/min. This developed urea biosensor is considered applicable for (portable) applications, such as artificial kidney systems and portable dialysis systems.

Robust preparation of tubular PTFE/FEP ultrafine fibers-covered porous membrane by electrospinning for continuous highly effective oil/water separation

We proposed a facile and robust strategy for fabricating tubular polytetrafluoroethylene (PTFE) / poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) ultrafine fibers-covered porous membranes for continuous oil/water separation via electrospinning-sintering method. Specifically, PTFE/FEP/poly (vinyl alcohol) (PVA) ultrafine fibers were electrospun covering on a porous supporting tube which served as the outer layer of the porous membranes. Manipulation of shapes by control of FEP additions enabled the creation of PTFE porous membranes with optimized membrane pore structure during the sintering process. Meanwhile, the obtained membranes had excellent oil/water selectivity in oil/water separation. Moreover, they could effectively separate surfactant-stabilized water-in-oil emulsions with separation efficiency as high as 99.9% and high flux (134 L m−2·h−1 at 0.5 bar). Therefore, tubular PTFE/FEP ultrafine fibers-covered porous membranes enabled an efficient separation for various oil/water emulsions, showing attractive potential for practical oil/water separation.