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Fouling Control Using Temperature Responsive Membranes composed of N-isopropylacrylamide (NIPAAm) and Iron Oxide Nanoparticles

Chede, Sneha A

Abstract Details

2015, Doctor of Philosophy, University of Toledo, Chemical Engineering.
Membrane fouling occurs when there is reversible or irreversible accumulation of macrosolutes present in the water on the membrane surface. Membrane cleaning and eventual replacement due to fouling can add to the operating costs of membrane systems. Reversible fouling can be minimized by crossflow operation and/or backflushing. On the other hand, irreversible fouling cannot be minimized during operation, often requires chemical cleaning, and may result in permanent flux decline. Among irreversible foulants, natural organic matter (NOM) is considered to be a major contributor. NOM is composed of a wide range of hydrophilic and hydrophobic components; hence, any stagnant hydrophobic or hydrophilic membrane has the potential to become fouled. Therefore, a dynamic membrane able to alternate between being more or less hydrophilic would be expected to decrease fouling. The purpose of this study was to cast stimuli responsive membranes to control fouling made of cellulose acetate (CA) and N-isopropylacrylamide (NIPAAm). NIPAAm is a stimuli-responsive polymer, which offers the potential to reversibly collapse or expand the membrane as a function of changes in temperature. Membranes were cast using phase inversion, were characterized chemically and morphologically, and were used in filtration experiments using bovine serum albumin (BSA), lipase and humic acid solutions. Flux studies were conducted at alternating cold and hot temperature cycles. CA-NIPAAm membranes displayed on average higher fluxes during operation, along with lower protein and humic accumulation on the membrane surface as compared to regular CA membranes. CA-NIPAAm membranes also showed higher flux recoveries as compared to CA membranes. Temperature activation of temperature-responsive membranes can be energy extensive since it requires heating entire housing and feed streams. Furthermore, heat transfer resistances within the housing can hinder the temperature response time of the membranes. To address these, heating was localized within the membrane matrix by embedding superparamagnetic iron oxide (SPIO) nanoparticles within the temperature-responsive NIPAAm polymer film. Nanoparticles were chemically attached to polyNIPAAm, and the resultant product was added to the dope solution. Membranes were fabricated and tested for their response to the RF heating. An alternating current (AC) electromagnetic field was used to activate the temperature responsive membrane via electromagnetic heating caused by nanoparticles. Membranes with nanoparticles were studied with and without RF heating, and the results suggested that during RF heating, CA-NIPAAm membranes with nanoparticles became less hydrophilic as compared to without RF heating. CA-NIPAAm membranes with and without SPIO nanoparticles were subjected to RF heating to investigate the effect of the presence of nanoparticles on water infiltration. Higher temperatures were recorded near the membranes with nanoparticles as compared to the membranes without nanoparticles suggesting that an oscillating magnetic field has the potential to be used for temperature activation. Finally, the performance of the membranes fabricated at the laboratory-scale and at production scale was evaluated. Since laboratory-scale doctor's blade method could become challenging during the scale up of the membranes, a well-developed pre-metered method, slot die extrusion, was used for continuous casting of liquid films. The feasibility of processing cellulose acetate membranes using a doctor’s blade versus a slot die extrusion was examined. The effects of processing methods, conditions, and substrate on the morphology and on the flux of CA membranes were studied. Membranes were tested for their performance under the same process conditions. Overall, membranes fabricated at the laboratory-scale and scale up were similar.
Isabel Escobar (Committee Chair)
Maria Coleman (Committee Member)
Yakov Lapitsky (Committee Member)
Saleh Jabarin (Committee Member)
Geoffrey Bothun (Committee Member)

Recommended Citations

Citations

  • Chede, S. A. (2015). Fouling Control Using Temperature Responsive Membranes composed of N-isopropylacrylamide (NIPAAm) and Iron Oxide Nanoparticles [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449426051

    APA Style (7th edition)

  • Chede, Sneha. Fouling Control Using Temperature Responsive Membranes composed of N-isopropylacrylamide (NIPAAm) and Iron Oxide Nanoparticles. 2015. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449426051.

    MLA Style (8th edition)

  • Chede, Sneha. "Fouling Control Using Temperature Responsive Membranes composed of N-isopropylacrylamide (NIPAAm) and Iron Oxide Nanoparticles." Doctoral dissertation, University of Toledo, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449426051

    Chicago Manual of Style (17th edition)