Good Filtration Efficiency Research Articles

Construction of highly efficient flame retardant cellulose nanofibrils/bamboo activated charcoal based composite aerogel sheet for excellent PM2.5 removal

Developing biomass air filter materials with efficient filtration for particulate matter 2.5 (PM2.5) and low pressure drop is a great challenge. Targeting this issue, cellulose nanofibrils (CNF) were employed as the skeleton materials mixing with bamboo activated charcoal (BAC), polyethyleneimine (PEI), and ammonium polyphosphate (APP) as the functional fillers, followed by freeze-drying and hydrophobic modification to prepare CNF/BAC based composite aerogel sheet for capture for PM2.5. The resulting aerogel sheet showed good filtration efficiency for PM2.5 (98.64 %), which benefited from the three-dimensional network structure from CNFs and PEI and electrostatic adsorption of both BAC and APP with negative charge. After reusing for 5 times, the filtration efficiency of the system could still maintain at 95.88 %. In addition, the introduced both APP and PEI made the system have excellent flame retardant through the synergistic effect of nitrogen and phosphorus. In view of excellent properties and simple preparation, this work supplies a promising way to prepare multifunctional biomass air filter.

Incorporating charged Ag@MOFs to boost the antibacterial and filtration properties of porous electrospinning polylactide films

Faced with the pollution caused by particulate matter (PM) in the air, the prevalence of infectious diseases, and the environmental burden by use of nondegradable polymers, the existing filter materials such as meltblown cloth of polypropylene cannot satisfactorily meet people's requirements. In this study, Ag nanoparticles were loaded onto ZIF-8 particles by impregnation reduction to prepare the positively charged Ag@ZIF-8. The porous fibrous membranes of Ag@ZIF-8 with polylactide (PLA) were manufactured by electrostatic spinning technology. Due to the inherently charged feature of Ag@ZIF-8 particles and the presence of pores on fibers, the prepared membranes showed a stable good filtration efficiency of over 97 % at different humidity (30–90%RH, relative humidity). Meanwhile, the presence of charge on Ag@ZIF-8 and the synergistic effects of Ag and ZIF-8 particles made the membranes exhibit good antibacterial effects. The width of the inhibition zone of 3 wt%Ag@ZIF-8/PLA membrane reached 1.33 mm for E. coli and 1.35 mm for S. aureus, respectively.

Analysis of Pleated Discrete Pore Non Woven Layer Type Filter Element for Naval Applications

In naval applications generally, the pleated discrete pore non-woven layer filter element is used. Filters used for such applications require maximized filtration rate, lower pressure drop, higher permeability, effective pore size distribution and good filtration efficiency. In other most common wire mesh filter element types, the geometric parameters are well defined and can easily be modelled. In the case of non-woven layer filter elements the pores are arranged in a randomly distributed manner and the modelling becomes difficult. In this present study a new approach was contemplated for modelling the same. The fluid flow through the filter element is by percolation phenomenon. Using Darcy’s law approach, the pressure drop across the filter element for different flow rates, were found analytically by considering the flow resistance in axial, radial and circumferential directions. The theoretical prediction made by CFD analysis is correlated with actual model behaviour and a good degree of correlation is obtained which shows the efficacy of this method for wider use in similar application. 
 

Commercial Janus Fabrics as Reusable Facemask Materials: A Balance of Water Repellency, Filtration Efficiency, Breathability, and Reusability.

Facemasks as personal protective equipment play a significant role in helping prevent the spread of viruses during the COVID-19 pandemic. A desired reusable fabric facemask should strike a balance of water repellency, good filtration efficiency (FE), breathability, and mechanical robustness against washing cycles. Despite significant efforts in testing various commercial fabric materials for filtration efficiency, few have investigated fabric performance as a function of the fiber/yarn morphology and wettability of the fabric itself. In this study, we examine commercial fabrics with Janus-like behaviors to determine the best reusable fabric facemask materials by understanding the roles of morphology, porosity, and wettability of the fabric on its overall performance. We find that the outer layer of the diaper fabric consisted of laminated polyurethane, which is hydrophobic, has low porosity (∼5%) and tightly woven yarn structures, and shows the highest overall FE (up to 54%) in the submicron particle size range (0.03-0.6 μm) among the fabrics tested. Fabric layers with higher porosity lead to lower-pressure drops, indicating higher breathability but lower FE. Tightly woven waterproof rainwear fabrics perform the best after 10 washing cycles, remaining intact morphologically with only a 2-5% drop in the overall FE in the submicron particle size range, whereas other knitted fabric layers become loosened and the laminated polyurethane thin film on the diaper fabric is wrinkled. In comparison, the surgical masks and N95 respirators made from nonwoven polypropylene (PP) fibers see over a 30% decline in the overall FE after 10 washing cycles. Overall, we find that tightly woven Janus fabrics consisting of a low porosity, a hydrophobic outer layer, and a high porosity and hydrophilic inner layer offer the best performance among the fabrics tested as they can generate a high overall FE, achieve good breathability, and maintain fabric morphology and performance over multiple washing cycles.

Investigating the Functional and Comfort properties of a Face Mask Based on a Coolmax® Blended Cotton Fabric

Abstract As the spread of Covid-19 has created a fatal threat to human survival, a comfortable and virus-deactivated functional face mask is extremely necessary. Herein, an appropriate thermally comfortable and highly breathable as well as virus-protecting functional knit fabric face mask was developed that consisted of multichannel PE Coolmax® yarn with cotton yarn. Due to the multichannel structure (four and six channels) of PE Coolmax® yarn with cotton yarn blended fabric, the fiber showed good filtration efficiency, air permeability, water vapour permeability and moisture management properties. In addition, the thermal conductivity and absorptive properties of the blended fabric based on the properties of PE Coolmax® yarn with cotton yarn make the face mask more comfortable for the user.

Green electrospinning of chitin propionate to manufacture nanofiber mats

Chitin is the second most abundant biopolymer after cellulose in nature, and it is currently under-utilized partially because of its insolubility in common solvents. Herein, chitin was propionylated to improve its dissolution in green solvents, i.e., ethanol and water, and manufactured nanofibers and nonwoven mats via electrospinning with poly(ethylene oxide) (PEO) as a co-spinning aid. Polymer solution viscosity, electrospun CP/PEO fiber morphology, mechanical, thermal, dynamic thermal, and surface contact angle of nanofiber mats were evaluated. Results showed that fibers with CP content up to 97% could be produced. The electrospun CP/PEO nanofiber mats exhibited good mechanical strength, thermal stability, and hydrophobicity with water contact angles up to 133°. Filtration test of separating carbon nanofibers and carbon nanotubes from water demonstrated the potential use of the CP/PEO nanofiber mats in fluid filtration of fibrous pollutants.

Experimental study on PM2.5 removal by magnetic polyimide loaded with cobalt ferrate

Abstract A novel functional magnetic polyimide loaded with cobalt ferrite nanoparticles by coprecipitation method was proposed, and XRD, FTIR, SEM technologies were employed to study their physicochemical properties. The filtration performance of non-magnetic and magnetic polyimide were examined by experimental system. The effects of dust resistance, filtration velocity and initial dust concentration on the filtration performance of magnetic polyimide were investigated under different dust loadings. The results revealed that presence of ρ-л conjugation between the cobalt ferrite and polyimide fiber resulted in easily load on the fiber surface for cobalt ferrite nanoparticles. The magnetic polyimide exhibited good filtration efficiency especially in the range of particle size less than 2 µm. The filtration efficiency of magnetic polyimide filter materials increased by nearly 20% compared with the primary polyimide. Due to the loading of cobalt ferrite, the resistance of the magnetic polyimide increased, while the resistance growth rate decreased from 100% to 29% with increased filtration velocity from 0.5 m/min to 2.5 m/min.

A nanofiber-based filter composed of electrospun PA-66/TiO2 nanofibers for removal of cement dust

ABSTRACT In the present work, a novel nanofiber-based filter has been presented which is comprised of composite nanofibers of polyamide-66 and TiO2 nanoparticles (PA-66/TiO2) for trapping cement dust. The produced nanofibers under optimum conditions were characterised by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effect of some important electrospinning process parameters on the obtained electrospun nanofibers including solution concentration, flow rate, voltage‚ tip to collector distance and the presence of salt was investigated. Studies showed that the solution concentration of 15 wt. % of PA-66 resulted in thinner and smother nanofibers than the other solution concentrations and also the average diameter of the electrospun nanofibers was decreased with increasing 1 wt. % salt to the polymer solution. The produced nanofiber-based filter can be applied for capturing cement dust with a good filtration efficiency of 97% for 3–500 nm particles and a quality factor in the range of 0.069–0.034 Pa−1

Preparation and filtration performance of the circular weft-knitted seamless weft-insertion fabric materials

Air particulate matter pollution has become a severe environment concern calling for filtration materials with great filtration performance. As the development of seamless forming technology, knitted filtration materials gradually show great potential. This study aimed to develop a novel kind of knitted seamless structure for filtration materials of filter bags with high production efficiency and excellent filtration performance. A new type of the circular weft-knitted seamless weft-insertion fabric (CKSW) filtration materials were developed on the modified circular knitting machine. This CKSW filtration materials consisting of the ground yarns, connection yarns and weft-insertion yarns, polyester full drawn yarns, and polyester draw texturing yarns with different yarn configurations were employed to realize series of CKSW samples. The polytetrafluoroethylene filaments with tourmaline particles were used to verify whether the static electric material produced an adsorption filtration effect on the CKSW filtration materials or not. After pretreatment, the filtration performance of the CKSW filtration materials was evaluated by analyzing its pore size, porosity, and filtration efficiency. Ultimately, the CKSW filtration materials with ground yarns and weft insertion yarns of draw texturing yarn and the connection yarns of full drawn yarn exhibited the most excellent filtration performance. The CKSW filtration materials show a high porosity of 87.14%, the pore size of 67.55 µm, and good filtration efficiency of 91.57% with the particles size of ≥ 5.0 µm. The successful fabrication of such knitted filtration materials may provide ideas for the development of filtration materials with new architecture mainly used as filter bags for baghouse.

Fabrication of epoxy resin reinforced polyimide (PI) nanofibrous membrane

Electrospinning is an emerging technique to fabricate nanofibrous nonwoven membranes, but the weak mechanical strength of electrospun products is blocking their applications. In this research, the PI nanofibrous nonwoven membranes were afforded via electrospinning and reinforced by facilely dipping into a diluted epoxy resin solution. There was fusion of fibers at the points of contact or cross among them, which provided about 4 times stronger strength than that of pristine PI ones and higher elongation at break. Furthermore, the epoxy reinforced PI membrane was not fuzzing and had strong adhesion to substrates. They exhibited good filtration efficiency and did not increase pressure-drop overwhelmingly although the average pore size reduced. This research suggested a feasible strategy to fabricate epoxy resin reinforced nanofibrous membranes, which would be promising applications in air filtration, battery’s separator, water treatment etc.

Airborne Nanoparticles Filtration by Means of Cellulose Nanofibril Based Materials

Nanoparticles in air are of particular concern for public health and employee exposure in work-places. Therefore, it is very important to prepare effective filters for their removal. In this work filters were prepared from nanocellulose, i.e. cellulose nanofibrils (CNF). CNF was produced using two methods giving two different qualities of CNF. One quality had negative charges on the fibril surfaces while the other was neutral, and had in addition thinner fibrils compared to the other qualities. Filter samples were produced from water dispersions of CNF, by removal of the water by freeze drying. The performance of the CNF based filters was assessed and compared with filters based on synthetic polymer fibres. The ability to collect NaCl particles with a broad size distribution, ranging from nanometer to micrometer scale, was determined. CNF filters showed quality values comparable with the synthetic polymer based filters. Filters based on both the two CNF qualities had very good filtration efficiency for a given pressure drop across the filter.

Characteristics and Preparation of PVDF Catalytic Membrane Modified by Nano-TiO2/Fe3+

The polyvinylidene fluoride (PVDF)/Fe3+-TiO2 catalytic membrane was prepared by sol-gel method. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectrum (FT-IR), mechanics capability, water flux, pepsin retention, porosity and contact angle etc. The catalytic activity of PVDF/Fe3+-TiO2 catalytic membrane was evaluated by the degradation of refractory dye Orange IV in the presence of H2O2. The results show that the addition of appropriate nano-sized TiO2 sol in the preparation of PVDF membrane has greatly improved some properties of the membrane such as microstructure, hydrophilic ability, mechanics intensity and water flux etc. The addition of Fe3+ ion in the preparation of PVDF membrane has greatly improved its catalytic activity to decompose H2O2. The catalytic activity of PVDF/Fe3+ -TiO2 is increased with the increase of the content of Fe3+ ion. When the content of Fe3+ _TiO2 sol is 21%, the content of Fe3+ ion is from 0.02% to 0.12%, the discolorization rate of Orange IV in this Fenton-like oxidation is from 61.2% to 90.5%. The catalytic activity of PVDF/Fe3+-TiO2 is not changed with the increase of the content of nano-sized TiO2. This kind of PVDF/Fe3+ -TiO2 catalytic membrane has not only good filtration efficiency but also good catalytic activity to effectively decompose H2O2.

Nanofabric nonwoven mat for filtration smoke and nanoparticles

The process of production of filtration mats of various thickness from PVC and PVDF polymers by the electrospinning method is presented in the paper. Filtration of nanoparticles and submicron particles is an important problem in industry and health protection systems, in particular in air-conditioning and ventilation appliances. This problem can be effectively solved by application of non-woven fibrous filtration mats. The experimental investigations of mechanical properties of nanofibrous filtration mats produced by electrospinning and the measurements of removal efficiency of submicron particles from flowing gas have indicated potential usefulness of these nanomats for gas cleaning of air-conditioning systems and/or ventilation ducts. The experimental results obtained for cigarette smoke of a mass median diameter of about 1 μm, used as test particles, have shown that nonwoven nanofibrous filtration mats produced by electrospinning have a good filtration efficiency for nano- and submicron particles, owing to a pressure drop similar to HEPA filters. Particles of this size are particularly difficult to be removed from the flow by a conventional method, for example, by a cyclone or electrostatic precipitator.

Preparation and properties of Fe3+/PVDF-PMMA catalytic membrane

A new kind of Fe3+/polyvinylidene fluoride membrane (PVDF)-poly methyl methacrylate (PMMA) asymmetric catalytic membrane was prepared by the blending method. The hydrophilicity and antifouling properties of Fe3+/PVDF catalytic membrane was increased significantly after blended with PMMA. The influence of some factors such as polymer blending ratio, polymer concentration, additives, temperature of coagulation bath on the pure water flux, and BSA retention were discussed. The catalytic activity of Fe3+/PVDF-PMMA catalytic membrane was evaluated by the degradation of refractory dye Orange IV in the presence of H2O2. The results showed that the addition of appropriate PMMA in the preparation of Fe3+/PVDF membrane has greatly decreased the contact angle of the membrane. Fe3+/PVDF-PMMA membrane had better anti-fouling than Fe3+/PVDF membrane. The Fe3+/PVDF-PMMA catalytic membrane’s retention rate decreased and pure water flux increased with the increase of PMMA. When the mass ratio of (PVDF)/(PMMA) was 7:3 and the additive was poly (ethylene glycol) (PEG600), the properties of this membrane were better. This kind of Fe3+/PVDF-PMMA catalytic membrane has not only good filtration efficiency but also good catalytic activity to effectively decompose Orange IV.

The Development and Property Studies of Nonwoven Filtering Materials for Car Air-Conditioner

With the development of automotive industry, automotive air-conditioning filter became the essential equipment in people’s daily life. On today’s market, there is half of the filtration equipment made from non-woven materials because of its small resistance, good filtration efficiency, high yield and low cost advantages. In this paper, based on the comparison and analyses of the web structure, fiber distribution and finesse, permeability, thickness and filtration efficiency of the newly developed nonwoven composites and other imported materials, the results were got that the finer fibers, more porosity, thinner thickness and smaller holes together would make an ideal filtering product for using in the cleaner car.

Preparation and characterization of antimicrobial polycarbonate nanofibrous membrane

Electrospinning of polycarbonate (PC)/chloroform solution with quaternary ammonium salt (benzyl triethylammonium chloride, BTEAC) was investigated to develop antimicrobial nanofibrous membranes for ultrafiltration. With BTEAC additive, ultrafine PC fibers were continuously generated and densely mounted without the blockage of spinning tip on electrospinning. When small amounts of BTEAC were added to the PC solution, the average diameter was also decreased from several micrometers to submicron range. It was found that the conductivity of the PC solution was a major parameter affecting the morphology and diameter of the electrospun PC fibers as well as the electrospinnability of PC. The nanofibrous membranes electrospun from the PC solution with BTEAC exhibited better excellent antimicrobial activity than those prepared without BTEAC. The PC nanofibrous filter shows a good filtration efficiency to satisfy the criterion of HEPA filter, and the pressure drop of the PC filters are within the normal range. Therefore, PC nanofibrous membrane showed a great potential as a candidate for ultrafiltration, compared to a commercial HEPA filter.

Reduction of soot pollution from automotive diesel engine by ceramic foam catalytic filter

Recent progress in diesel technology demonstrates the possibility of reducing the particulate matter (PM) emissions level combining the high efficiency of common rail engine with exhaust gas after-treatment devices, such as diesel PM filter. Ceramic foam catalytic filter (CFCF), prepared by coating of ceramic foam (CFUF), results in lower temperature and shorter regeneration time due to the higher specific surface, lower pressure drop and good filtration efficiency with respect to CFUF.

Polymeric nanofiber web-based artificial renal microfluidic chip

In this paper, we present a new method for the creation of a smaller dialyzer and do so by incorporating polymeric nanofiber web, which is known to have good filtration efficiency for broad particle sizes, into a poly (dimethylsiloxane)-based microplatform. We have developed a process that makes possible the efficient production of polyethersulfone and polyurethane nanofiber web and that, itself, incorporates an electrospinning method. We have combined the nanofiber web with the PDMS-based microfluidic platform to create a chip-based portable hemodialysis system. With the dialyzing chip, we evaluated the filtration capability of molecules in broad ranges of sizes and compared the filtration capability of nanofiber membranes with that of PES and polyvinylidene fluoride porous membranes (sheet type): we discovered that the nanofiber membranes have better filtration performance than the other membranes. Blood cells were not mechanically affected during their filtration and their transportation through the chip. In conclusion, we have demonstrated the feasibility of chip-based hemodialysis, and we expect that our method suggested in this paper will be applied to the development of small light-weight dialyzers for the realization of portable hemodialysis systems.

Ceramic-filter behavior in gasification

Enviropower Inc., a joint venture of Tampella Power Inc. and Vattenfall Engineering AB, is developing a new process for power generation based on the integrated gasification combined cycle (IGCC). This IGCC concept incorporates the pressurized fluidized-bed gasification of different solid fuels (the U-Gas process), applying air-blown gasification and hot gas cleanup. Ceramic candle filters are evaluated to be the best candidate at present for high-temperature and high-pressure (HTHP) filtration of the gasifier gas. Filter behavior was examined as a part of the gasification pilot-plant test program. According to the results, ceramic candle filters have a good filtration efficiency, although the reliability of filtration technology is not yet at commercial level.

Breeding of bialaphos producing strains from a biochemical engineering viewpoint

A breeding study was performed from the viewpoint of biochemical engineering to obtain strains which produce bialaphos (a herbicide) with high productivity and high yield from inexpensive substrates under low oxygen supply, with good filtration efficiency and easy downstream treatment. After induing mutagenesis using conventional chemical mutagens, first selection on agar culture was made to obtain strains which exhibited a large inhibition zone with a small colony, without being influenced by carbon catabolite regulation and with suppression of product decomposition. Subsequently, in a liquid culture system, selection was made to obtain strains which exhibited high product concentrations under low oxygen supply, with good filtration efficiency. A strain thus obtained was found to have about five hundred times higher product concentration than the wild strain. It also enabled us to use an inexpensive carbon source and to produce bialaphos under low oxygen supply, with good filtration efficiency.