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Electrospun polyamide 6 (PA 6) and polyamide 6/6 (PA 6/6) nanofibers were produced in order to investigate their experimental characteristics with the goal of obtaining filtration relevant fiber media. The experimental design model of each PA nanofibers contained the following variables: polymer concentration, ratio of solvents, nanofiber media collection time, tip-to-collector distance, and the deposition voltage. The average diameter of the fibers, their morphology, basis weight, thickness, and resulting media solidity were investigated. Effects of each variable on the essential characteristics of PA 6/6 and PA 6 nanofiber media were studied. The comparative analysis of the obtained PA 6/6 and PA 6 nanofiber characteristics revealed that PA 6/6 had higher potential to be used in filtration applications. Based on the experimental results, the graphical representation—response surfaces—for obtaining nanofiber media with the desirable fiber diameter and basis weight characteristics were derived. Based on the modelling results the nanofiber filter media (mats) were fabricated. Filtration results revealed that nanofiber filter media electrospun from PA6/6 8% (w/vol) solutions with the smallest fiber diameters (62–66 nm) had the highest filtration efficiency (PA6/6_30 = 84.9–90.9%) and the highest quality factor (PA6/6_10 = 0.0486–0.0749 Pa−1).

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The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)).

Thermoplastic polymers serving numerous practical applications are widely used in modern societies. For example, thermoplastic polystyrene is used as packaging and building insulation material, while thermoplastic nylon due to its extreme durability and strength is widely used to manufacture textile articles. However, disposal or recycling of used thermoplastic polymer items is problematic and expensive. Thermoplastic polymer waste can be successfully transformed into nano-fibres by electro-spinning. Electro-spinning is an inexpensive method where nano-fibres are generated by a charged jet of polymeric solution in a high-voltage electric field. When the jet travels in the air the solvent evaporates and charged fibres are collected on a grounded rotating drum. The diameter of nano-fibres ranges from 100 to 2000 nm and depends on the appropriate polymer solvent system, technological parameters, and environmental conditions. Due to low basis weight, large surface area to volume ratio, high pore volume, tight pore size and relatively uniform fibre size, utilised polystyrene waste could be used in nano-fibre air filters. The experimental results show that nano-fibre air filters meet High-Efficiency Particulate Air (HEPA) filtration standard, where filtration efficiency of the most penetrating particles (0.3 μm) is >85 %, and can be used to filter hazardous chemicals, biological and radioactive particles from air streams.