Capillary Flow Porometer Research Articles

Fabrication of a Plate-Type Porous Stainless Steel 316L Powder Filter with Different Pore Structures without Use of a Binder

Generally, when fabricating porous filters using metal powder, about 1 to 2 wt% of a binder is added to increase the formability of the metal powder. If the binder is not completely removed through a debinding and sintering process, however it can cause defects such as discoloration and the generation of fine particles. In this study, a study was conducted to fabricate a plate-type porous stainless steel powder filter with a different pore structure without the use of a biner. First, the metal powder is charged into a ceramic mold to form a plate-shaped powder filter, and then covered with a ceramic top plate. In order to observe the pore properties according to the pressure, the unpressurized specimen and the specimen pressurized with a pressure of 30 MPa were then sintered at 1050℃ for one hour in a high vacuum atmosphere furnace. The microstructure of the sintered plate-shaped powder filter was observed through an optical microscope and in order to analyze its pore properties as a filter, gas permeability and porosity were measured using a capillary flow porometer and Archimedes’ law.

Porosity determination of textile fabrics: A novel mathematical approach and experimental validation

Porosity is a crucial parameter that regulates permeability, comfort, and pathogen barriers in textile materials. A fabric with greater porosity allows for greater moisture exchange but is less effective as a pathogen barrier. So engineering the fabric to meet both comfort and barrier properties are essential. Various methods (airflow, liquid penetration, and Image processing) are used to determine the fabric's porosity after fabric manufacturing. The mathematical calculation of fabric porosity before fabric manufacturing will become very helpful for precise fabric development. This research paper introduces an innovative and customized mathematical model designed to determine the porosity and pore size of fabrics, utilizing essential parameters such as areal density, thickness, yarn diameter, and yarn linear density. The effectiveness of the modified equation for fabric porosity is tested by using twelve different fabric samples with different areal densities in experiments. The comprehensive testing conducted provides evidence of the adaptability and resilience of the suggested model, highlighting its potential for wider utilization within the sector. The pore size of the prepared fabrics is measured by a capillary flow poro-meter (CFP), and porosity is measured by image analysis using Python programming. A perfect positive correlation has been observed between calculated and experimental porosity values.

Innovative sound absorption technique: Step‐shaped ceramic fiberboards with veneer attachment for walls

AbstractThe subject of the present paper is improving sound absorption properties and protecting the dust generation of ceramic fiber boards. The two‐microphone impedance tube method measured the sound absorption coefficient (SAC) of ceramic fiberboards (CFB) with different shapes and sizes. The wood veneer was used to cover the ceramic fiberboard (VCFB) surface to improve the wall's appearance and prevent dust generation. The step‐shaped ceramic fiberboards with veneer attached (VCFBS) revealed improved SAC (.98, 2000 Hz) compared with CFB and VCFB. The noise reduction coefficient (NRC) and sound absorption average showed a 100% improvement compared to CFB. The surface morphology and air permeability were analyzed using a scanning electron microscope and a capillary flow porometer to correlate with the findings. Furthermore, the porosity and pore diameter of the CFB were also studied to gain a comprehensive understanding of its acoustic properties and sound absorption capabilities. Statistical T‐tests revealed significant variations in the SAC (p ≤ .005). Besides, the obtained SAC was compared with other reported sound‐absorbing materials. These findings suggest that using step‐shaped ceramic fiberboard covered with a wood veneer can significantly absorb sound and improve the living environment. This novel approach offers potential advancements in sound‐absorbing materials for building construction.

An improved procedure for calculating the pore size distribution of filter cloths in capillary flow porometry

Pore size distribution is one of the most important structural characteristics of filter cloths and can, in theory, be used to predict filtration performance. Capillary flow porometry is a common method to determine the pore diameter(s) and the pore size distribution of a porous material. Equipment applying this method has many advantages, but data processing and further calculations still require refining to be fit for purpose in calculations of flow capacity. The present study aims to develop a new procedure for processing volumetric flow rate data and corresponding pressure, which are measured by capillary flow porometry. The processed data are further used to calculate the pore size distribution of textile materials. Six industrial samples of polypropylene filter cloth were examined using scanning electron microscopy and capillary flow porometry. The raw data measured by the capillary flow porometer were processed using the developed method that considers changes in flow regimes as pressure increases. In addition, the nonideality of pores, originating from tortuosity, an irregular cross-sectional shape of the pore, and the number of pores, were considered in calculations by combining all these characteristics in one single parameter. This work shows that pores in a textile material are not ideal cylinders. The standard pore size distribution calculations should consider an imperfect pore structure and, therefore, be corrected.

Study on pore size distributions of microporous polymer membranes having different physical architecture using capillary flow porometry

Capillary flow porometry (CFP) is an emerging technique to measure the most constricted part of the through pores in membranes. In our previous work, the technique was successfully tested for track-etch membranes, which are model membranes with straight cylindrical pores. In this work, this technique has been used to measure the mean pore size, smallest pore size, and bubble point pore size for commercially available microporous membranes such as poly(propylene), poly(ethersulfone), poly(tetrafluoroethylene), and poly(vinylidene fluoride). The scanning electron microscopy images revealed that these membranes have different microporous architecture with no well-defined pores in these membranes. The study is important because the pore architecture in these membranes is not straight and cylindrical, as assumed by CFP. Also, the influence of different parameters such as the shape factor, wetting liquid, and tortuosity on the performance of capillary flow porometer has been studied. It is seen that it is important to incorporate shape factor for CFP measurements of membranes with such pore architecture for obtaining the reliable results. The studies with different wetting liquids (Porefil, dodecane, and 1-decanol) show that for the membranes studied, dodecane can serve as a wetting liquid to obtain information about membrane pore sizes, without much effect on the results. The technique has been applied to measure the pore size distribution of highly cross-linked poly(vinylbenzylchloride) pore-filled membranes synthesized in our laboratory.

A study on the effects of the addition of graphene oxide and multi-walled carbon nanotubes for surface modification on polyvinylidene fluoride membranes

We report graphene oxide (GO) and multi-walled carbon nanotube (MWCNT)-based polyvinylidene fluoride (PVDF) to improve the nanopore properties of pure PVDF for water treatment. The surface properties such as morphology, size of pores, and hydrophilicity were characterized using an optical microscope, FE-SEM, Raman spectra, and a capillary flow porometer. The membrane performance was evaluated for free residual chlorine and water flux. GO and MWCNTs were uniformly synthesized in the PVDF, and the hydrophobic properties of pure PVDF became hydrophilic because of the oxygen functional group of GO and the hydrophilic functional group of MWCNTs. The membrane with GO dramatically increased the number of pores from 145 to 1,197, with greater pore depth than that of pure PVDF. Additionally, the free residual chlorine removal performance of the GO and MWCNTs added PVDF was about 270 % and 415% improved compared to the pure PVDF and commercially used ultra-filter, respectively. These results reveal that the number and size of pores on the PVDF can be controlled and performance of the water treatment can be increased by the addition of carbon nanomaterials.

Evaluation of gas permeability in porous separators for polymer electrolyte fuel cells: Computational fluid dynamics simulation based on micro-x-ray computed tomography images.

Pore structures and gas transport properties in porous separators for polymer electrolyte fuel cells are evaluated both experimentally and through simulations. In the experiments, the gas permeabilities of two porous samples, a conventional sample and one with low electrical resistivity, are measured by a capillary flow porometer, and the pore size distributions are evaluated with mercury porosimetry. Local pore structures are directly observed with micro-x-ray computed tomography (CT). In the simulations, the effective diffusion coefficients of oxygen and the air permeability in porous samples are calculated using random walk Monte Carlo simulations and computational fluid dynamics (CFD) simulations, respectively, based on the x-ray CT images. The calculated porosities and air permeabilities of the porous samples are in good agreement with the experimental values. The simulation results also show that the in-plane permeability is twice the through-plane permeability in the conventional sample, whereas it is slightly higher in the low-resistivity sample. The results of this study show that CFD simulation based on micro-x-ray CT images makes it possible to evaluate anisotropic gas permeabilities in anisotropic porous media.

Modification of polyacrylate resin to prepare water‐soluble poly‐epoxy‐acrylate resin for its application as an automotive oil filter paper binder

AbstractIn this work, poly‐epoxy‐acrylate (PEA) resin was prepared by modifying polyacrylate resin with epoxy resin through a simple solution polymerization method. The prepared PEA resin was then neutralized by alkaline treatment to obtain excellent water solubility and used as an ecofriendly binder for automotive oil filter paper. The effect of alkaline neutralization degree on the water solubility of the PEA resin was studied. Also, the influence of epoxy content on the grafting degree of PEA resin was tested. The mechanical strength and oil resistance properties of oil filter paper strengthened by the prepared PEA resin were compared to other commercial binders. The microstructure and pore size of the oil filter paper were observed by scanning electron microscope and tested by capillary flow porometer (PMI), respectively. The results show that the prepared PEA resin can greatly enhance the mechanical and oil resistance properties of the oil filter paper while maintaining its filtration properties. The prepared PEA resin has the potential to be used as an ecofriendly water‐based binder for automotive oil filter paper.

Jute Felt for Noise Reduction: Understanding Effect of Pore Size Distribution

ABSTRACT Effect of pore size and its distribution on the noise reduction coefficient of jute felt were studied through capillary flow porometer and impedance tube. The inter-criteria correlation method was used to optimize the type of jute felts to obtain noise reduction coefficient of 0.5. The porometry study of the needle punched jute felt suggested the gradient pore structure of felt due to presence of needling induced inverted cone of pores within fibrous mass. The jute felt with an areal density 796.5 g/m2 with mean pore diameter 60.32 µm offered optimum noise reduction coefficient of 0.5. The percentage weight of pore distribution in the range of 45≥ ∅ <25 µm was 44.61%, indicated that to achieve an objective of NRC≥ 0.5 the most influential pore diameter range was 45≥ ∅ 25.The increased number of jute fiber per unit area of felts from 55 to 430 resulted in narrowing of inter fiber spaces and consequently reduced the mean pore size. Further increase in number of fibers ultimately leads to blocking of spaces within fibers and get compacted like a solid fibrous mass.

Bacteria Adhesion of Textiles Influenced by Wettability and Pore Characteristics of Fibrous Substrates.

Bacteria adhesion on the surface is an initial step to create biofouling, which may lead to a severe infection of living organisms and humans. This study is concerned with investigating the textile properties including wettability, porosity, total pore volume, and pore size in association with bacteria adhesion. As model bacteria, Gram-negative, rod-shaped Escherichia coli and the Gram-positive, spherical-shaped Staphylococcus aureus were used to analyze the adhesion tendency. Electrospun webs made from polystyrene and poly(lactic acid) were used as substrates, with modification of wettability by the plasma process using either O2 or C4F8 gas. The pore and morphological characteristics of fibrous webs were analyzed by the capillary flow porometer and scanning electron microscopy. The substrate’s wettability appeared to be the primary factor influencing the cell adhesion, where the hydrophilic surface resulted in considerably higher adhesion. The pore volume and the pore size, rather than the porosity itself, were other important factors affecting the bacteria adherence and retention. In addition, the compact spatial distribution of fibers limited the cell intrusion into the pores, reducing the total amount of adherence. Thus, superhydrophobic textiles with the reduced total pore volume and smaller pore size would circumvent the adhesion. The findings of this study provide informative discussion on the characteristics of fibrous webs affecting the bacteria adhesion, which can be used as a fundamental design guide of anti-biofouling textiles.

Study on proanthocyanidins crosslinked collagen membrane for guided bone tissue regeneration.

The goal of this study is to understand the ability of a newly developed barrier membrane to enhance bone tissue regeneration. Here in this study we present the in vitro characterization of the barrier membrane made from type I collagen and crosslinked by oligomeric proanthocyanidins (OPCs). The effects of the membrane (P-C film) on cell cycle, proliferation, alkaline phosphatase activity, and mineralization were evaluated using the human osteoblast cell line MG-63, while the barrier ability was examined using MG-63 cells, as well as the human skin fibroblast cell line WS-1. The pore size is one of the factors that plays a key role in tissue regeneration, therefore, we evaluated the pore size of the membrane using a capillary flow porometer. Our results showed that the mean pore size of the P-C film was approximately 7-9 µm, the size known to inhibit cell migration across the membrane. The P-C film also demonstrated excellent cell viability and good biocompatibility, since the cell number increased with time, with MG-63 cells proliferating faster on the P-C film than in the cell culture flask. Furthermore, the P-C film promoted osteoblast differentiation, resulting in higher alkaline phosphatase activity and mineralization. Therefore, our results suggest that this P-C film has a great potential to be used in guided bone regeneration during periodontal regeneration and bone tissue engineering.

Comparisons between Geotextile Pore Sizes Obtained from Capillary Flow And Dry Sieving Tests

Abstract In the United States of America, two standard methods of measuring the largest pore size of a geotextile have been accepted: Dry Sieving Test (ASTM D4751, Standard Test Methods for Determining Apparent Opening Size of a Geotextile) and Capillary Flow Test (ASTM D6767, Standard Test Method for Pore Size Characteristics of Geotextiles by Capillary Flow Test). Despite several drawbacks of Dry Sieving Tests, such as the amount of time required; tendency of glass beads to become trapped, including trapping of glass beads inside the geotextiles; likelihood of imprecise preparation of glass beads; and potential electrostatic effects, the largest pore size (apparent opening size [AOS], O95) results obtained from Dry Sieving Test still determines many filtration criteria. Although the Capillary Flow Test was approved in 2002, it is still not widely adopted, despite the fact that it provides the largest pore size (Bubble Point, O98) and a complete pore size distribution of a geotextile. Decades of analyses searched for a correlation between the Dry Sieving and Capillary Flow Test results; however, none of them have been widely accepted because of the limited number of geotextiles used and a lack of proper calibration. The current study investigates a possible correlation between the Dry Sieving and Capillary Flow Test results with 51 woven, nonwoven, and composite geotextiles. The Capillary Flow Porometer was calibrated using four thin metal plates with known pore openings and two membranes. This study describes the challenges experienced during the Capillary Flow Test and factors affecting the test results. One finding is that the cleaning of calibration materials and equipment with Methanol plays an important role in the Capillary Flow Test results. The use of different shape factors, contact angles, and wetting liquids in the analyses are also considered. The outliers of Capillary Flow Test results were removed from the analysis using a box plot and whisker diagram, and a good correlation between AOS and Bubble Point (R2 = 0.78) was established.

High acoustic absorption properties of hackberry compared to nine different hardwood species: A novel finding for acoustical engineers

Wood is one of the most usable natural composite. Noise pollution from the various sources affect the human health and environment worldwide. How to reduce noise pollution has become a major issue? Hence, finding the proper sound absorbing wood is necessary for improved acoustic environment. In the present work, we choose most useful ten different hardwood species. Analysis of basic properties, surface morphology by HR-FESEM, elemental analysis using EDAX, cellulose crystallites by XRD, air permeability by a capillary flow porometer, sound absorption coefficient and sound transmission loss by microphones transfer function method using impedance tube is discussed in detail. The Hackberry wood shows better sound absorption coefficient (0.640 at 4000 Hz), sound transmission loss (15.23 at 4000 Hz) due to the higher value of Darcy permeability constant (9.78), porous surface morphology and lower cellulose crystallites (16.6%). These results became extremely important to the engineers for designing good acoustic housing environment.

High‐Pressure Jet Cleaning of Polymeric Microfiltration Membranes

AbstractThe cleaning effect of a high‐pressure jet of water on a polymeric microfiltration membrane was investigated at different pressures, durations, and angles. The angle of 70° at a pressure of 130 bar and a cleaning duration of 10 s were found to be promising parameters. Throughput measurements show that this cleaning method can restore about 80 % of the initial throughput of the membrane. Analyses by capillary flow porometer and UV‐vis spectrophotometer imply that an impact on the membrane was detectable after 1800 cleaning cycles at a pressure of 130 bar. Therefore, high‐pressure jet cleaning is a promising method for mechanical cleaning of track‐etched microfiltration membranes.

Do Face Masks become Worthless after Only One Use in the COVID-19 Pandemic?

BackgroundDue to coronavirus disease 2019 (COVID-19), world-wide face mask use is increasing exponentially. These face masks are difficult to recycle, and their accumulation contributes to enormous environmental threats. In this study, we hypothesize that the face mask can be reused as long as it retains its original structure, which will slow the environmental impacts.Materials and MethodsWe selected common disposable surgical masks for this study and classified test conditions based on wear time and reuse method. After wearing the mask for 10 hours, we let it dry naturally in the shade for 14 hours. The specimens were measured by scanning electron microscope and capillary flow porometer.ResultsThe pore structure of the mask did not change when worn 4 times for 10 hours each time, and there was no significant pore structure change when impregnated with ethyl alcohol (purity 95%), treated with UV or steam, or run through a washing machine.ConclusionThe pore structure of the surgical mask was not changed significantly after 40 hours of use. Surgical mask pore structure did not change significantly after treatment with ethyl alcohol, UV light, steam, or a washing machine.

Cellulose Nanofibrous Membranes Modified with Phenyl Glycidyl Ether for Efficient Adsorption of Bovine Serum Albumin

Hydrophobic interaction chromatography (HIC) as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries. However, the low binding capacity and slow adsorption rate of the currently available HIC media lead to a little supply and high price of the highly purified proteins. Herein, nanofibrous membranes with hydrophobic binding sites were developed for HIC by directly coupling phenyl glycidyl ether on the hydrolyzed cellulose acetate nanofiber membrane (cellulose-phenyl NFM). Scanning electron microscope (SEM), water contact angle (WCA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area analysis and capillary flow porometer (CFP) were applied to evaluate the physically and chemically structural transformation. The obtained cellulose-phenyl NFMs showed a proper hydrophilcity (WCA = 37°), a relatively high BET surface area (3.6 times the surface area of commercial fibrous membranes), and tortuous-channel structure with through-hole size in the range of 0.25–1.2 μm, which led to a little non-specificity adsorption, high bovine serum albumin adsorption capacity of 118 mg g−1, fast adsorption process within 12 h, good long-term stability and reusability. Moreover, compared with traditional modification methods which always include activation and graft two steps, direct coupling method is more efficient for HIC media fabrication. Therefore, cellulose-phenyl NFMs with outstanding protein adsorption performance could be a kind of promising candidate for HIC.

A novel high-durability oxidized poly (arylene sulfide sulfone) electrospun nanofibrous membrane for direct water-oil separation

Water-oil separation complicated fabrication procedures and low stability seriously hindered the separation membrane from using in the practical water-oil application. Here we present a novel oxidized poly (arylene sulfide sulfone) (O-PASS) nanofibrous membrane using simple electrospinning technology, which has high durability and is directly applied to water-oil separation. The results of scanning electron microscopy and capillary flow porometer show that the fiber diameters of membranes were 378 ± 37 nm and the average pore sizes were 1.81 ± 0.22 μm with narrow distribution. Furthermore, excellent hydrophobicity (139.6°) oleophilic (0°), good oil adsorption capacity (1 5 0), and high flux (623.1 L·m−2·h−1) render O-PASS nanofibrous membrane highly effective separation of water-oil. The separation efficiency of the O-PASS nanofibrous membrane is 99%. More importantly, this membrane could endure extremely harsh environments, such as strong acid (aqua regia), strong alkali (0.1 M sodium hydroxide solution), strong polarity solvent (1, 3-Dimethyl-2-imidazolidinone) for 90 days and high temperature (120 °C) for 12 h. Finally, the O-PASS nanofibrous membrane exhibits good mechanical property reaching 5.51 MPa. This study provided good chemical resistant and hydrophobic membrane that could be directly used in harsh environment for efficacious water-oil separation.

Low band-gap energy photocatalytic membrane based on SrTiO3–Cr and PVDF substrate: BSA protein degradation and separation application

A series of ultrafiltration (UF) membranes based on mixed matrix of chromium-doped strontium titanate (SrTiO3–Cr) photocatalyst and polyvinylidene difluoride (PVDF) were systematically prepared by non-solvent induced phase inversion technique. Porous PVDF membrane and mixed matrix membranes (MMMs) incorporated with 3–10 wt% SrTiO3–Cr were produced in the UF range using polyethylene glycol as a porogen additive. The crystal morphology and electronic property of as-synthesized Cr-doped SrTiO3 nanoparticles were characterized by XRD and UV–Vis DRS. We found that the SrTiO3–Cr nanoparticles are cubic perovskite structure of approximately 30–40 nm in size with a low band gap energy of 2.05 eV. The morphology, surface roughness, hydrophilicity and textural properties of SrTiO3–Cr/PVDF MMMs were comprehensively characterized using field emission-scanning electron microscope with energy-dispersive X-ray spectroscopy, atomic force microscope, sessile drop technique, and capillary flow porometer. The SrTiO3–Cr was observed to be homogeneously dispersed in all the MMMs and provided additional anti-fouling properties from Bovine Serum Albumin (BSA) protein. The membrane UF property and tri-cycling performance were evaluated under three distinct protocols in (1) Dark, (2) constant UVA exposure, and (3) UVA during post-treatment clean only. By increasing the SrTiO3–Cr concentration, the MMMs displayed an improved homogeneity and macropore distribution with enhanced water permeability given by 51–110 LMH bar−1 pure water flux and 37 to 45 LMH bar−1 BSA water flux in the Dark. A consistently high BSA rejection of 95% and an improved anti-fouling property under constant UVA irradiation were achieved due to a combination of photo-induced hydrophilic and photocatalytic effect. Also, a significant improvement in UF performance in terms of membrane flux recovery was observed in the 3rd protocol signifying that the effect of protein fouling on membrane filtration was further reduced due to a lower degree of BSA fragment deposition in the membrane pores. The findings in this study dramatically lower the operational constraints (transmembrane pressure, membrane cleaning, use of UVA) in the protein filtration process and offer an innovative membrane material for the research of photo-induced, anti-fouling membranes for protein separation applications.

Effective chromium removal from water by polyaniline-coated electrospun adsorbent membrane

Polyaniline (PAni)-coated polyvinylidenefluoride-co-hexafluoropropilene (PVDF-HFP) nanofibrous membranes were fabricated by electrospinning of PVDF-HFP followed by in-situ polymerization of PAni on the nanofiber surface. The resulting membranes with PAni coating were applied for chromium removal, where the efficiency was evaluated as functions of the pH value and adsorption time. Dynamic adsorption tests were also carried out at different flow rates and volumes of chromium in water. It was found that the PAni coating greatly enhanced the chromium removal efficiency with the maximum adsorption capacity being 15.08 mg/g at pH = 4.5. The desorption study further confirmed the recyclability of the PAni coated PVDF-HFP membrane showing an efficiency over 70% even after 5 cycles of usage. The structure and property relationships of these membranes were also characterized by FTIR spectroscopy, capillary flow porometer, water contact angle, scanning electron microscopy and X-ray photoelectron spectroscopy.

Preparation and application of zinc oxide/poly(m‐phenylene isophthalamide) hybrid ultrafiltration membranes

ABSTRACTA small molecular‐weight cut‐off (MWCO) of 6000 Da poly(m‐phenylene isophthalamide) (PMIA) embedded zinc oxide (ZnO) hybrid ultrafiltration (UF) membrane was synthesized via nonsolvent‐induced phase separation (NIPS). Tests of field emission scanning electron microscope (FE‐SEM), energy dispersive X‐ray spectroscopy (EDX), atomic force microscopy (AFM), thermal gravimetric analyzer (TGA), Fourier transform infrared (FTIR), capillary flow porometer (CPF), mechanical test, and pure water flux (PWF) for characterization of membranes were carried out. The EDX, FTIR, and TGA indicated the presence of ZnO in the polymer matrix. The hybrid membranes showed enhanced pore density, PWF by the presence of the particles. The contact angle and water flux of modified membrane with 0.03 wt % of nano‐ZnO were 47.7° and 52.58 L·m−2·h−1compared to 71.6° and 36.27 L·m−2·h−1respectively; Compared with the hydrophobic membrane, the PMIA membrane, with hydrophilicity, is supposed to exhibit good antifouling properties. Furthermore, the thermal stability and mechanical properties of the modified membranes were increased. Finally, the hybrid membrane was used in treating papermaking white wastewater and exhibited good separation and high water flux. The great properties of the ultrafiltration PMIA membranes indicate their potential for excellent performance in industrial applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47583.