Test Methods for Pore Size Characteristics of Membrane Filters by Bubble Point and Mean Flow Pore Test

Nanofibrous media have a low basis weight, high permeability and small pore size that make them appropriate for a wide range of filtration applications, particularly for smaller particles. In contrast to electrostatic filter media, nanofibers' filtration efficiencies depend on the mechanical filtration mechanism and do not degrade with time. In this study, the National Institute for Occupational Safety and Health (NIOSH) requirements for the N95 particulate filtering half mask were achieved using electrospun cellulose acetate (CA) and polyvinylidene fluoride (PVDF) nanofiber coated polypropylene spunbond layers. Specifically, 16 and 15% (w/v), and 14, 12 and 10% (w/w) polymer concentrations were selected for CA nanofibers and PVDF nanofibers, respectively, to adjust the nanofiber diameters. The diameters of CA and PVDF nanofibers were decreased with decreasing polymer concentration for both CA (319.02 to 264.02 nm) and PVDF (236.50 to 142.59 nm) nanofibers. The thickness of the electrospun 16CA, 15CA and 14PVDF, 12PVDF, 10PVDF mats was adjusted by varying the collection period (15 min, 30 min, 60 min). The effects of electrospun CA and PVDF nanofiber diameter on the pore size and the thickness of the mats were compared in terms of filtration performance. 16CA with a nanofiber diameter of 319.02 nm had the largest first bubble point of 26.5 µm and mean flow pore size of 5.71 µm at 15 min with a thickness of 0.019 mm. The smallest first bubble point and mean flow pore values and the smallest pore size were achieved with the finest nanofibers of 10PVDF. Filtration performances were given as initial penetration and air flow resistance (ΔP). 16CA-60 min and 15CA-30 min mats both met the NIOSH requirements with their bulky structure. For PVDF, thinner nanofibers with smaller pores were produced compared to the CA nanofibers, and the NIOSH requirements were only achieved using double-layered, face-to-face 10PVDF-15 min nanofiber mats with the penetration of 1.85% and ΔP of 33.87 mmH2O.

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Transfer Technique for Electron Microscopy of Membrance Filter Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005278x ◽

1974 ◽

Vol 32 ◽

pp. 554-555

Author(s):

Lawrence W. Ortiz ◽

Bonnie L. Isom

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Pore Size ◽

Membrane Filters ◽

Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

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Filterability of Polysulfone Membrane in a Tilted Panel System for Activated Sludge Filtration

Water ◽

10.3390/w12123533 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3533

Author(s):

Ahmad Aliyan Alif Ismail ◽

Sri Mulyati ◽

Sri Aprilia ◽

Mohd Hizami Mohd Yusoff ◽

Normi Izati Mat Nawi ◽

...

Keyword(s):

Activated Sludge ◽

Pore Size ◽

Membrane Fouling ◽

Aeration Rate ◽

Membrane Properties ◽

Mean Flow ◽

Clear Trend ◽

Polysulfone Membrane ◽

Tilting Angle ◽

Filtration System

Membrane bioreactors (MBRs) are established technology for treatment of domestic and industrial wastewater because they offer a small footprint and high quality of effluent, in addition to lower excess sludge. However, their widespread applications are still limited by higher expenditure for compensating for membrane fouling. In this study, polysulfone (PSF)-based ultrafiltration membranes were developed and integrated with a tilted panel system for fouling control in activated sludge filtration. The results show an enhanced performance of filtration system thanks to the mutual advantage of the tilted panel system and the membrane properties. Both membranes showed a clear trend of higher permeability with respect to the tilted panel parameters, namely, higher tilting angle, higher aeration rate, and shorter intermittent/switching period. PSF-1 (1 wt% polyethylene glycol (PEG) additive) shows significantly better performance than PSF-3 (3 wt% PEG additive) although their mean flow pore size, structural properties, and contact angle do not differ significantly. PSF-1 shows superior filterability performance of about 45% for panel tilting angles of 20° at an aeration rate of 1.8 L·min−1, and 11% for a switching period of 1 min compared with PSF-3. The key property enhancing the performance of the PSF-1 is its narrower distribution of pore size. Overall results suggest that an optimum system could be achieved by optimizing both the filtration system and the membrane material properties.

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Fabrication and Characterization of Diatomite Functionalized Cellulose Acetate Nanofibers

AATCC Journal of Research ◽

10.14504/ajr.6.3.4 ◽

2019 ◽

Vol 6 (3) ◽

pp. 28-36

Author(s):

Çiğdem Akduman

Keyword(s):

Pore Size ◽

Cellulose Acetate ◽

High Specific Surface Area ◽

High Porosity ◽

Size Distributions ◽

Mean Flow ◽

Water Contact ◽

Pore Size Distributions ◽

Nanofiber Membranes

Cellulose acetate (CA) nanofiber membranes incorporated with diatomite (DE) were prepared by electrospinning to produce electrospun nanofiber membranes with high specific surface area and high porosity with fine pores. When the DE percentage increased from 0 to 30%, the water contact angle (WCA) of the membranes increased from 86.21° to 118.44°, indicating that neat CA nanofibers were more hydrophilic than CA/DE nanofibers and had a better wetting tendency. CA, CA-10DE, and CA-20DE nanofiber membranes showed a mean flow pore size (MFP) of 2.941, 2.681, and 2.408 μm, respectively, with narrow pore size distributions. However, the CA-30DE nanofiber membrane showed a smaller MFP size of 0.5014 μm. CA nanofibers were produced in the range of 206.31 to 281.13 nm. The dye removal ability of these membranes was tested using an aqueous solution of C.I. Reactive Red 141.

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