Airborne Nanoparticles Filtration by Means of Cellulose Nanofibril Based Materials (original) (raw)
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Desalination and Water Treatment, 2015
Cellulose is one of the most abundant natural polymers. Combined with its unique properties, cellulose nanofibers, therefore, have potential applications in industry. Electrospinning is a convenient technique that is widely used to make nanofibers. This process, however, needs optimization in order to fine tune the produced nanofibers. The current study investigates the effects of varying the different electrospinning parameters on the quality and monodispersity of the produced nanofibers. Cellulose acetate (CA), a cellulose precursor, is used in this regard. Solutions containing different concentrations of CA, up to 20% by weight, were electrospun into micro-nanofibers. The produced nanofibers were characterized by SEM, DSC, and IR techniques. Results showed the crucial dependence of the nanofibers monodispersity on the CA solution concentration, the applied voltage, the flow rate, the spinning distance, and the nature of atmosphere surrounding the electrospinning setup. Optimally prepared CA membranes as well as two commercially available filtering membranes were utilized in the removal of tiny solid particulates from drinking water media.
Journal of Cleaner Production, 2019
Polyamideamine-epichlorohydrin resin (PAE) is one of the most commonly used wet strength agents in the papermaking industry. However, adsorbable organic halogens (AOX) are known to be a toxic side product of the PAE manufacturing process; therefore, the use of PAE is restricted by regulation for food and medical applications. In this study, we investigated partially replacing the indirect food additive, PAE, with a renewable, biodegradable material, cellulose nanofibres (CNF), in order to drastically reduce the amount of PAE used while maintaining the same wet tensile strength. The concept is to replace covalent bonds by hydrogen bonds and to drastically increase bonding area. Depth-type filters were prepared with cellulose (30%), perlite (70%) and lesser amounts of PAE via papermaking technique. A small fraction of cellulose fibre composition was substituted with CNF while the PAE amount was gradually decreased. The substitution of positively charged PAE for negatively charged cellulose nanofibres switched the overall charge of the system from cationic to anionic. Therefore, two cationic polyelectrolytes, CPAM or PEI, were investigated to control the overall charge and adsorption performance of the filter system. The substitution of CNF enabled PAE dosage to be reduced by over 95% while retaining the wet strength properties of the filters. The wet strength obtained from the small quantity of wet strength polymer could be further improved by increasing the curing temperature to 150 C with a much shorter curing period. The filters with reduced PAE dosage have also improved adsorption of positively charged contaminants. However, for negatively charged contaminants a very minor amount (around 20 mg/g) of cationic polymer addition would be required to maintain the performance. Our study shows that partial replacement of conventional papermaking fibres with cellulose nanofibres allows us to reduce the quantity of wet strength polymer remarkably and achieve a sustainable and environmentally-friendly concept for filter manufacturing or for any paper product requiring wet strength.
ACS Omega
Aerosol particle filtration in most penetrating particle size (MPPS) region is of great challenge for conventional nonwoven filter mats. The present work, therefore, redesigns conventional filter mats by introducing porous structure. A combination of thermally induced phase separation and breath figure mechanism was employed to synthesize porous cellulose triacetate fibers, in conjunction with the volatile solvent methylene chloride. The ambient humidity, the concentration of the polyvinylpyrrolidone (PVP) secondary polymer, and the ethanol cosolvent were all adjusted to modify the Taylor cone formation, jet stability, and fiber porosity. After fiber formation, the PVP was removed to obtain a superhydrophobic material. To distinguish the effect of pores, the performance of porous and nonporous nanofibers having similar sizes was conducted. Tests were performed using various dust particle sizes, and the results show that the collection efficiency of the porous fibers, resulting from particle diffusion, inertial impaction, and interception, was improved. Interestingly, the efficiency of the porous fibers in the MPPS region was exceptionally enhanced (up to 95%), demonstrating that the presence of dynamic pores greatly contributes to particle capture.
Application of Nanofibres in Filtration Processes
Mechanisms of capture of dust particles, two-and three dimensional modelling of properties of filtration materials and effect of selected variables on electrospinning of polyurethane (PU) solutions are discussed with the aim to prepare a nanofibre structure capable of capturing ultrafine particles. The two-dimensional modelling is used to gain an idea of the effect of mass per square area, thickness of nanofibre layers and nanofibre diameter on filtration efficiency of ultrafine particles. Values of filtration efficiency calculated at the three-dimensional modelling of the filtration process are compared with experimental measurements for sets of filtered particles 100 nm in diameter or bigger. The most important characteristics affecting quality of nanofibre materials are nanofibre diameter, porosity and homogeneity of nanofibre layers. The method making possible to achieve the required diameter of the nanofibres is demonstrated on the influence of relative humidity and solvent type on the fibre-forming process taking place in an electrostatic field. The effect of homogeneity of the nanofibre deposition on the collecting substrate is assessed employing images from scanning electron microscopy (SEM) and tests of filtering abilities of the nanofibre layers. Also, some measurements obtained when nanofibres were used in filtration of air, liquids and dispersions of carbon nanotubes in a liquid are presented.
Use of Nano Fibers in Filtration -A Review
— Filtration is an effective separation process and textile materials are being used since ages as the media for this separation. Conventional textile filter media consist of natural as well as man-made fibres with fibre diameters usually in the range 1– 50 µm. Fibres with finer fibre diameter are supposed to provide higher surface are finer degree of filtration i.e. better filter efficiency. From this consideration, filter media made of nano-fibre enable new levels of filtration performance for several applications ranging from industrial, medical and consumer as well as filtration processes required in defence application. Nano fibres are defined as fibres having diameter of 500nm or less and are readily accessible by the electrospinning process
Design of biodegradable cellulose filtration material with high efficiency and breathability
Using respiratory protective equipment is one of the relevant preventive measures for infectious diseases, including COVID-19, and for various occupational respiratory hazards. Because experienced discomfort may result in a decrease in the utilization of respirators, it is important to enhance the material properties to resolve suboptimal usage. We combined several technologies to produce a filtration material that met requirements set by a cross-disciplinary interview study on the usability of protective equipment. Improved breathability, environmental sustainability, and comfort of the material were achieved by electrospinning poly(ethylene oxide) (PEO) nanofibers on a thin foam-formed fabric from regenerated cellulose fibers. The high filtration efficiency of sub-micron-sized diethylhexyl sebacate (DEHS) aerosol particles resulted from the small mean segment length of 0.35 μm of the nanofiber network. For a particle diameter of 0.6 μm, the filtration efficiency of a single PEO layer varied in the range of 80-97 % depending on the coat weight. The corresponding pressure drop had the level of 20-90 Pa for the airflow velocity of 5.3 cm/s. Using a multilayer structure, a very high filtration efficiency of 99.5 % was obtained with only a slightly higher pressure drop. This opens a route toward designing sustainable personal protective media with improved user experience.
Polymeric Nanofibers in Air Filtration Applications
Nanofiber is a broad phrase generally referring to a fiber with a diameter less than 1 micron. While glass fibers have existed in the sub-micron range for some time and polymeric meltblown fibers are just beginning to break the micron barrier, sub-half-micron diameters have been used for air filtration in commercial, industrial and defense applications for more than twenty years. This paper will discuss a process for making nanofibers, as well as the benefits, limitations, construction, and performance of filters using nanofiber media. In particular, nanofibers provide marked increases in filtration efficiency at relatively small (and in some cases immeasurable) decreases in permeability. In many laboratory tests and actual operating environments, nanofiber filter media also demonstrate improved filter life and more contaminate holding capacity.
2017
Ldays, the quality ofvehicle' s cabin air has become one of the health concerns a lffiers. Typical air filters used in an air conditioning system of a vehicle are m: 1fiber materials such as fiberglass and polymeric materials. Nanofibers have a tial to be used as high efficient filter materials due to their nanoscale diameters. facturers claim that filters made of nanofibers can trap dusts or particles with % efficiency. However, there is limited information available on the effectiven ospun nanofiber filter media in filtering submicron particulates. Therefore, this ned at developing and studying the performance of nanofiber-coated filte1 ng submicron particles. The filters were incorporated with electrospun ny ibers at 1 Ok V of applied voltage and 10 em spinning distance. The coated filten lced at varying collection times ranging from 1 to 10 minutes. The filter sample~ I using a dedicated test rig to simulate an actual air conditioning system. Parti :r (PM) measurement techni...
Using of Nanofiber Filter for Air Filtration in Water Supply Facilities
2014
The air is a medium that is commonly used for various water treatment methods or it is in very close touch with treated water. Untreated air can content significant amount of pollutants. Contact of polluted air with treated water causes interactions of both media which results in water contamination. Nanofiber filter has numerous prerequisites for high quality and efficiency of air treatment. Testing of nanofiber filter efficiency, analyses of proper filter type for different air filtration purposes and measure of disinfection effects was researched and compared with commonly used filter. Functionality of the filters was verified on prototype unit. The test of passive contamination corresponded to interaction in water tanks. Physical parameters such as velocity, flow, temperature and pressure difference of the filters were measured for the test. Also microbiological samples of examined filters, filtrated air and saturated water were evaluated. Analyses of measured values confirmed e...
ACS Applied Materials & Interfaces, 2019
Ultrafine particulate aerosols less than 100 nm diffuse randomly in the air and are hazardous to the environment and human health. However, no technical standards nor commercial products apply for filtering particle sizes under 100 nm yet. Here we report the development of a porous poly(L-lactic acid) (PLLA) nano-fibrous membrane filter with an ultra-high specific surface area via electrospinning and a post-treatment process. After PLLA fibres were electrospun and collected, they were treated by acetone to generate a blossoming porous structure throughout each individual fibre. Characterizations of morphology, crystallinity, mechanical and thermal properties demonstrated that the porous structure can be attributed to the non-solvent induced spinodal phase separation during electrospinning and solvent induced recrystallization during post treatment. The blossoming porous structure with high specific surface area contributed to excellent filtration efficiency (99.99%) for sodium chloride (NaCl) ultrafine aerosol particles (30-100 nm) with a low pressure drop (110-230 Pa). Notably, under 7.8 cm/s air flow rate, the membrane samples performed better for filtering smaller-sized aerosol particles than the larger ones when evaluated by the quality factor (0.07). Finally, this finding demonstrates that the electrospun membrane with hierarchical pore structure and high specific surface area hold great potential in applications as air filtering materials.