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Full text release has been delayed at the author's request until May 07, 2025

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Fabrication of Charged Fibrous Structures and their Applications in the Filtration and Separations

Bokka, Sreevalli
http://rave.ohiolink.edu/etdc/view?acc_num=akron1649957914826724

Abstract Details

, Doctor of Philosophy, University of Akron, Chemical Engineering.
Filter media are generally used in various filtration applications. Few of the applications of the filter media are to separate dispersed water droplets from the diesel fuel or to separate the solid aerosols from the gas stream. Filter membranes currently available in the market show a filtration efficiency of >95% but higher efficiencies usually correspond to higher pressure drops. High-pressure drop is undesired as they result in a higher cost of operating the filter membranes. Electret filters have known to attract particles from the fluid stream thus achieving high filtration efficiency but at a lesser pressure drop. The main objective of this work was to prepare a charged fibrous structure that can be used in filtration applications with high filtration efficiencies and reduced flow resistance. The charged fibrous structures evaluated in this research were flat fibrous membranes and fiber yarns. To analyze the effects of charges on these fibrous structures, both the membrane and yarn samples were polarized using a custom fabricated polarization device. Samples were polarized by simultaneously stretching, heating, and electrifying to orient the dipoles. For this, a piezoelectric polyvinylidene fluoride (PVDF) polymer was selected as the fiber material of the samples. Nonpolarized and polarized samples in the fibrous structures of membranes and yarns were evaluated for charge and filtration performances. The charge measurements showed the fiber yarn samples had nearly twice the charge per sample mass as the fiber membrane structures. The characterization study showed that the mechanical stretching during electrospinning of the yarns resulted in more dipole orientation which resulted in higher charges on the fiber yarn samples compared to the randomly oriented membrane structures where lower mechanical stretching was observed during electrospinning. An FTIR analysis determined the fraction of  phase in yarn samples was nearly twice that of the membrane structures indicating the fiber yarn structures were more effective in preparing charged fibrous structures. Fiber yarn samples were evaluated for the separation of solid aerosol particles from an aerosol stream. Cylindrical yarn wound filter elements with the same thickness of the fiber yarn around the filter element had similar filtration efficiencies for the nonpolarized and polarized samples. It was observed that the filtration efficiency and flow restriction increased with an increase in fiber yarn thickness. Since the nonpolarized yarns showed similar charge measurements to that of the polarized membrane, very slight change in the filtration performance was observed comparing aligned polarized and aligned nonpolarized fiber yarns. Prior work has been performed to produce the polarized PVDF filter membrane and to study the capture efficiency for the filtration of solid aerosols. However, not much literature is available to study these charged filter membranes for the separation of dispersed water droplets from the ultra-low sulfur diesel (ULSD) fuel. In this work, nonpolarized and polarized fiber membranes were studied for the separation of dispersed water droplets from the ultra-low sulfur diesel (ULSD) fuel. The results showed that with the polarization of the fiber membrane a slight increase in the pore size and permeability was observed. From the separation of dispersed water droplets from the ULSD fuel, it was observed that with similar filtration efficiency, the polarized filter membranes had shown a nearly 20-40% reduction in the pressure drop compared to the nonpolarized filter membrane.
George G Chase (Advisor)
Edward A Evans (Committee Member)
Nicholas G Garafolo (Committee Member)
Sadhan C Jana (Committee Member)
Zhenmeng Peng (Committee Member)
199 p.
Chemical Engineering
Fibrous structures, Charged fiber filter membranes, Filtration, Separations, Aligned fibers, Fiber yarn

Recommended Citations

Citations

  • Bokka, S. (2022). Fabrication of Charged Fibrous Structures and their Applications in the Filtration and Separations [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1649957914826724

    APA Style (7th edition)

  • Bokka, Sreevalli. Fabrication of Charged Fibrous Structures and their Applications in the Filtration and Separations . 2022. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1649957914826724.

    MLA Style (8th edition)

  • Bokka, Sreevalli. "Fabrication of Charged Fibrous Structures and their Applications in the Filtration and Separations ." Doctoral dissertation, University of Akron, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=akron1649957914826724

    Chicago Manual of Style (17th edition)

akron1649957914826724
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This open access ETD is published by University of Akron and OhioLINK.