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    Aerosol filtration performance of nanofibrous mats produced via electrically assisted industrial-scale solution blowing
    (Wiley, 2021) Gungor, Melike; Toptas, Ali; Calisir, Mehmet Durmus; Kilic, Ali
    Highly efficient polyamide 6 (PA6)-based nanofibrous air filter media was developed for particulate matter (PM) removal in the ambient atmosphere. The PA6 nanofibrous mats exhibited 85% PM0.3 capture performance at a cost of 164 Pa pressure drop when the multiple-nozzle solution blowing system was set to 8 m/h fabric winding speed. However, an increase in the winding speed at a constant feeding rate lowered the filtration efficiency to 62% due to the less amount of nanofibrous mats collected on the substrate. The application of electrical field at the same parameters allowed us to produce a filter media having FFP3-level filtration performance, which means 99% PM0.3 capture performance. This was attributed to a fine fiber diameter (116 nm), higher solidity value (0.149), and lower average pore size (2.28 mu m). These results show that the electrically assisted solution blowing provides a feasible route for the production of high-quality nanofibrous filter media.
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    Aerosol Filtration Performance of Solution Blown PA6 Webs with Bimodal Fiber Distribution
    (Amer Chemical Soc, 2022) Gungor, Melike; Selcuk, Sule; Toptas, Ali; Kilic, Ali
    A bimodal web, where both nanofibers and microfibers are present and distributed randomly across the same web, can deliver high filter efficiency and low pressure drop at the same time since in such a web, filter efficiency is high thanks to small pores created by the presence of nanofibers and the interfiber space created by the presence of microfibers, which is large enough for air to flow through with little resistance. In this work, a bimodal polyamide 6 (PA6) filter web was fabricated via a modified solution blowing (m-SB) technique that produced nanofibers and microfibers simultaneously. Scanning electron microscope (SEM) images of the webs were used to analyze the fiber morphology. Additionally, air permeability, solidity, porosity, filtration performance, and tensile strength of the samples were measured. The bimodal filter web consisted of nanofibers and microfibers with average diameters of 81.5 +/- 127 nm and 1.6 +/- 0.458 mu m, respectively. Its filter efficiency, pressure drop at 95 L min-1, and tensile strength were 98.891%, 168 Pa, and 0.1 MPa, respectively. Its quality factor (QF) and tensile strength were 0.0268 Pa-1 and 0.1 MPa, respectively. When compared with commercially available filters, the bimodal web produced had superior filter performance, constituting a suitable alternative for air filter applications.
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    Centrifugally spun micro-nanofibers based on lemon peel oil/gelatin as novel edible active food packaging: Fabrication, characterization, and application to prevent foodborne pathogens E. coli and S. aureus in cheese
    (Elsevier Sci Ltd, 2022) Dogan, Nurcan; Dogan, Cemhan; Eticha, Andinet Kumella; Gungor, Melike; Akgul, Yasin
    This study aimed to develop innovative micro-nano fibers loaded with lemon peel essential oil for food packaging via centrifugal spinning. Lemon peel essential oil (LPO) was extracted from dried lemon peel by hydrodistillation. The major one of the 16 components of the extract detected by GS-MS was limonene (60.4%). Gelatin fibrous mats loaded with three different concentrations of LPO were fabricated with centrifugal spinning and then crosslinked. Micro-nanofibers were characterized in encapsulation efficiency, morphological, chemical, thermal, hydrophobicity and microbiological aspects. The in-vitro evaluation showed that the effect of fibers on grampositive Staphylococcus aureus (S. aureus) ATCC 29213, especially due to the antimicrobial activity of limonene, was greater than that of gram-negative Escherichia coli (E.coli) ATCC 35218. This effect was also consistent with the in-situ evaluation in which micro-nano fibers were applied to contaminated cheeses. Moreover, LPOloaded gelatin centrifugal spun positively affected the shelf life by suppressing the growth of aerobic mesophilic bacteria and yeast molds that cause spoilage in cheese.
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    Clogging performance of micro/nanofibrous laminated composite air filter media
    (Sage Publications Inc, 2022) Calisir, Mehmet D.; Gungor, Melike; Toptas, Ali; Donmez, Utkay; Kilic, Ali; Karabuga, Semistan
    The performance of fibrous filter media relies on factors such as particle capture efficiency, pressure drop and clogging time. Fiber diameter, porosity and packing density are important web-based factors to improve final filtration performance. In this study, composite nonwoven webs were produced using spunbonded, meltblown and electroblown mats to obtain filter media with different fiber diameter, porosity and packing density. Such a layered composite approach caused huge differences in porosity and packing density, which resulted with improved clogging performance. The average fiber diameter was found to be 65 +/- 19.4 nm for electroblown layer (N), while that was 1.17 +/- 0.38 mu m for meltblown (M) and 17.64 +/- 2.65 mu m for spunbond (S) layers. NM (nanofiber+meltblown) configuration provided 12-13% lower mean flow pore size, which resulted in faster clogging compared to NS (nanofiber + spunbond) mats. The thicker nanofibrous layer resulted in lower pore size and quality factor. Additionally, the composite samples showed a faster-rising pressure drop than the thick microfibrous mats due to smaller pores that clogged quickly. It was also shown that nanofiber coating causes a linear increase in pressure drop with dust loading, while microfibrous samples exhibited smooth plateau and linear increase after clogging point. Nanofiber layer facilitates cake formation which causes more difficult airflow, and lower dust holding capacity. Among the layered composite mats, the NM configurations were found to be more advantageous due to higher initial filtration efficiency and almost similar dust loading performance.
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    Enhancing filtration performance of submicron particle filter media through bimodal structural design
    (Wiley, 2024) Toptas, Ali; Calisir, Mehmet D.; Gungor, Melike; Kilic, Ali
    Depth filtration is a widely utilized mechanism for submicron aerosol filtration using disposable filter cartridges and facemasks. The filter media should be carefully engineered to reach high filtration efficiency and dust-loading capacity at the expense of a low-pressure drop (Delta P). Filter media with bimodal fiber diameter distribution enhance particle capture by creating small pores with tiny fibers, while microfibers improve airflow, reduce Delta P, and increase the effective filter area for particle retention. In this study, bimodal filters were achieved through the homogeneous distribution or layered use of nanofibers and microfibers. The impact of the bimodal design was explored using fibrous mats produced through melt-blowing, solution-blowing, and electroblowing methods. Keeping the basis weight of filter samples at 30 gsm, using four-layered filters (4L) improved air permeability compared to single-layer samples. The 4L sample exhibited the highest performance, achieving 99.52% efficiency at 148 Pa. Moreover, replacing the melt-blown layer with bimodal mats in the 4L design increased the filtration efficiency to 99.61% keeping Delta P nearly the same. The corona discharge treatment yielded the highest efficiency (99.99%) in the 4BML sample, even after 1 month the efficiency was maintained at 99.90%, highlighting the advantage of bimodal fiber distribution in electret filters.HighlightsFour-layered filter (4L) structures resulted in improved air permeability.Bimodal layer (BL) achieved by adding SB nanofibers into the melt blowing.BL in 4L structure increased the efficiency from 99.52% to 99.61%.Modified BL sample (4BML) provides the highest QF (0.044 Pa-1) after 1 month. Production of the layered bimodal mats in different structural designs and their filtration performance.image
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    Novel active food packaging based on centrifugally spun nanofibers containing lavender essential oil: Rapid fabrication, characterization, and application to preserve of minced lamb meat
    (Elsevier, 2022) Dogan, Cemhan; Dogan, Nurcan; Gungor, Melike; Eticha, Andinet Kumella; Akgul, Yasin
    This study aimed to develop novel nano fibers loaded with lavender essential oil (LEO) for food packaging via centrifugal spinning technique. LEO was extracted from dried lavender flowers by hydrodistillation. The dominant two of the 16 components of the extract identified by GS-MS were linalool (34.37 %) and linalyl acetate (28.82 %). PVP nanofiber mats loaded with three different concentrations of LEO were fabricated with centrifugal spinning and subsequently crosslinked. Nanofibers were characterized in encapsulation efficiency, morphological, mechanical, chemical, thermal, hydrophobicity and bioactivity aspects. The in-vitro antioxidant effect of nanofiber mats, which increased with the loaded LEO concentration, were determined by DPPH and ABTS methods. This effect was also consistent with the in-situ assessment where nanofibers were applied to minced lamb meat. Moreover, LEO-loaded PVP centrifugal spun positively affected the shelf life by suppressing the growth of aerobic mesophilic bacteria, psychotropic bacteria and, yeast molds that cause spoilage in meat.
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    Solution blown nanofibrous air filters modified with glass microparticles
    (Sage Publications Inc, 2021) Polat, Yusuf; Calisir, Mehmet; Gungor, Melike; Sagirli, Merve N.; Atakan, Raziye; Akgul, Yasin; Demir, Ali
    High-pressure drop and lower dust holding capacity reduce the performance of nanofibrous air filters. For that reason, this study was carried out to form filters with high-quality factor and high dust holding capacity, thanks to the glass particle additives. In this study, as an approach to such modifications, fluffy nanofiber webs were produced via solution blowing. Polyamide 6 (PA6) was chosen as the base for the nanofibrous mats, where glass microparticles were embedded as an additive to reduce web solidity. The effects of glass microparticle embedding on the filtration performance and pressure drop of the mats were investigated. SEM analysis was performed to analyze nanofiber diameter and morphology. Also, the barrier properties of samples were examined by air filtration and air permeability tests. Findings showed that the addition of glass particles did not alter fiber morphology significantly. However, lowering the pressure drop resulted in higher air permeability and better filtration performance in terms of the quality factor. Glass particles embedded composite samples exhibited a higher quality factor compared to the neat PA6 sample, and the PA6 + 5%GP sample has the highest quality factor value around 0.43. The filtration efficiency of this sample was 99.97% at an expense of 187.3 Pa pressure drop. The obtained enhancement was conducted to the lower solidity of composite webs which was 36% lower for the PA6 + 5%GP sample.