Final Report: Research and Demonstration of Electrospun Nanofiber Filters: Multifunctional, Chemically Active Filtration Technologies for Small-Scale Water Treatment Systems

EPA Grant Number: R835177
Title: Research and Demonstration of Electrospun Nanofiber Filters: Multifunctional, Chemically Active Filtration Technologies for Small-Scale Water Treatment Systems
Investigators: Cwiertny, David M. , Myung, Nosang V. , Parkin, Gene F
Institution: University of Iowa , University of California - Riverside
EPA Project Officer: Hiscock, Michael
Project Period: December 1, 2011 through November 30, 2016
Project Amount: $499,466
RFA: Research and Demonstration of Innovative Drinking Water Treatment Technologies in Small Systems (2011) RFA Text |  Recipients Lists
Research Category: Drinking Water , Water

Objective:

This research and demonstration plan aimed to fabricate multi-component nanofiber mats via a novel synthesis approach, electrospinning, and optimize their performance as chemically active filtration technologies for water treatment. The vision for this versatile, point-of-use (POU) water treatment technology is shown in Figure 1, in which nanotechnology is harnessed to shrink the size and scale of water treatment, while specific layers of the filter can be tailored to address a range of drinking water quality problems (e.g., disinfection byproducts, persistent organic pollutants, emerging micropollutants, metals, oxyanions and pathogens).

Summary/Accomplishments (Outputs/Outcomes):

This project successfully developed chemically functional nanomaterials for applications that promote environmental sustainability and more resilient water supplies. For nanomaterial fabrication, we rely upon the process of electrospinning (Figure 2), which yields high surface area nanofiber networks deployable as porous non-woven mats (Figure 3). It also allows facile control of nanofiber diameter (from ~20 nm to ~1 μm) using tunable synthesis variables (e.g., applied voltage, precursor solution viscosity, humidity) and the ability to manipulate nanofiber composition by integrating desired components directly into the spinning precursor solution. More practically, electrospinning is emerging as a high-yield, highly scalable process, producing robust nanofiber networks ideal for environmental application, often times using ambient conditions that minimize the energy intensity of nanomaterial synthesis.

 
 
As shown in Figure 3, we have used electrospinning to synthesize a variety of nanofibers for use in water treatment application including (1) photoactive titanium dioxide (TiO2), which can be used for disinfection and removal (via oxidation) of trace micropollutants; (2) metal oxide nanofibers targeting metals and oxyanions (e.g., lead, arsenic and chromium); and (3) carbon nanofibers for sorption of residual organics including persistent micropollutants and disinfection byproducts. Relative to traditional materials, our use of nanofibers holds the advantages that unlike traditional materials used in water treatment (e.g., granular activated carbon), the majority of their reactive surface area is external and thus more easily accessible during treatment applications. Further, given rising concerns over the inadvertent release of engineered nanomaterials into the environment and finished water supplies, nanofiber mats allow us to harness the positive reactivity benefits of engineered nanomaterials in a platform (a three-dimensional nanofiber network) that is robust and less prone to mobilization and/or leaching during application. Indeed, a priority of our research is developing strong, flexible nanofiber mats that can be easily manipulated and handled, which will promote their ease of use during application.
 
 
Figure 4. Adsorption isotherms for PAN/Fe2O3@Fe2O3 in red and a commercial sorbent in blue for (a) AsO43-, (b) CrO42-, (c) Cu2+, and (d) Pb2+. Experiments were conducted in pH 6 10 mM MES buffer. Isotherms are given in terms of mass adsorbed per surface area of adsorbent; lines are Langmuir model fits.
 
Figure 4 demonstrates the performance of the flexile polyacrylonitrile (PAN)-hematite composite (shown in Figure 3h). The data for the composite are shown in red, and their performance as a sorbent for several common metal pollutants is compared to a commercially available material marketed for metal removal. Toward all metals, the electrospun nanofiber composite exhibits higher capacity than this commercially available material, while also resulting in more rapid metal uptake (data not shown). This allows the use of less material and smaller technology footprints in water treatment.
 
We also have explored the application of these nanotechnologies in a flow-through filtration system, more representative of their application in point of use water treatment. As shown in Figure 5, as a result of their high surface area and reactivity, a relatively small mass (65 mg) of iron oxide functionalized polyacrylonitrile (as shown in Figure 3b) can treat nearly 6 L of water before any significant breakthrough. The chromate is irreversibly bound and captured, resulting in a safer and cleaner finished water supply. Water fed into this filtration system was at the MCL for chromate (100 ppb), and over the trial duration, all finished water quality remained well below the MCL. Using this same flow through, we have also successfully demonstrated the removal of metals other than chromate (e.g., lead, arsenic and copper) and a variety of pharmaceuticals and personal care products as emerging pollutants.

Conclusions:

Research Impact: To date, seven peer-reviewed research papers (with at least five more in review or preparation), nine presentations at national research meetings of the American Chemical Society and the Sustainable Nanotechnology Organization, and at the Gordon Research Conference on Environmental Nanotechnology. The paper by Nalbandian et al. (Environ. Sci. Technol., 2015) was named a “Top 10 Sustainable Chemistry Paper” by Chemical & Engineering News the year it was published.
 
Training Impact: This project supported participation from one postdoctoral researcher (Dr. Danmeng Shuai, now a professor at George Washington University), three Ph.D. students (Dr. Michael Nalbandian, Dr. Katherine Greenstein, and Dr. Katherine Peter) and several (5+) undergraduate research assistants (many from traditionally underrepresented groups in Science, Technology, Engineering and Mathematics or STEM).
 
Outreach: Materials and outcomes from this project have been integrated into several demonstration activities presented to K-12 students (at both participating institutions) on water treatment.
 
Policy Impact: Two manuscripts from this project were cited in the White Paper “Water Sustainability through Nanotechnology: Nanoscale Solutions for a Global-Scale Challenge” by the NTSC Committee on Technology, Subcommittee on Nanoscale Science, Engineering and Technology as part of the White House Nanotechnology Signature Initiative (available at: https://www.nano.gov/sites/default/files/pub_resource/water-nanotechnology-signature-initiative-whitepaper-final.pdf)


Journal Articles on this Report : 9 Displayed | Download in RIS Format

Other project views: All 21 publications 9 publications in selected types All 9 journal articles
Type Citation Project Document Sources
Journal Article Egodawatte S, Greenstein KE, Vance I, Rivera E, Myung NV, Parkin GF, Cwiertny DM, Larsen SC. Electrospun hematite nanofiber/mesoporous silica core/shell nanomaterials as an efficient adsorbent for heavy metals. RSC Advances 2016;6(93):90516-90525. R835177 (Final)
  • Abstract: RSC Advances-Abstract
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  • Other: ResearchGate-Abstract
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  • Journal Article Nalbandian MJ, Zhang M, Sanchez J, Choa Y-H, Cwiertny DM, Myung NV. Synthesis and optimization of BiVO4 and co-catalyzed BiVO4 nanofibers for visible light-activated photocatalytic degradation of aquatic micropollutants. Journal of Molecular Catalysis A: Chemical 2015;404-405:18-26. R835177 (2015)
    R835177 (Final)
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  • Abstract: ScienceDirect-Abstract
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  • Journal Article Nalbandian MJ, Zhang M, Sanchez J, Kim S, Choa Y-H, Cwiertny DM, Myung NV. Synthesis and optimization of Ag–TiO2 composite nanofibers for photocatalytic treatment of impaired water sources. Journal of Hazardous Materials 2015;299:141-148. R835177 (2012)
    R835177 (Final)
  • Full-text: ScienceDirect-Full Text HTML
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Nalbandian MJ, Greenstein KE, Shuai D, Zhang M, Choa Y-H, Parkin GF, Myung NV, Cwiertny DM. Tailored synthesis of photoactive TiO2 nanofibers and Au/TiO2 nanofiber composites:structure and reactivity optimization for water treatment applications. Environmental Science & Technology 2015;49(3):1654-1663. R835177 (2015)
    R835177 (Final)
  • Abstract from PubMed
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  • Abstract: ES&T-Abstract
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  • Other: ES&T-Full Text PDF
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  • Journal Article Nalbandian MJ, Zhang M, Sanchez J, Kim S, Choa Y-H, Nam J, Cwiertny DM, Myung NV. Synthesis and optimization of Fe2O3 nanofibers for chromate adsorption from contaminated water sources. Chemosphere 2016;144:975-981. R835177 (2015)
    R835177 (Final)
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Nalbandian MJ, Zhang M, Sanchez J, Nam J, Cwiertny DM, Myung NV. Mesoporous θ-alumina/hematite (θ-Al2O3/Fe2O3) composite nanofibers for heavy metal removal. Science of Advanced Materials 2017;9(1):22-29. R835177 (Final)
  • Abstract: Science of Advanced Materials-Abstract
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  • Other: ResearchGate-Abstract
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  • Journal Article Peter KT, Vargo JD, Rupasinghe TP, De Jesus A, Tivanksi AV, Sander EA, Myung NV, Cwiertny DM. Synthesis, optimization, and performance demonstration of electrospun carbon nanofiber-carbon nanotube composite sorbents for point-of-use water treatment. ACS Applied Materials & Interfaces 2016;8(18):11431-11440. R835177 (Final)
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  • Abstract: ACS-Abstract
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  • Other: ACS-Full Text PDF
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  • Journal Article Peter KT, Johns AJ, Myung NV, Cwiertny DM. Functionalized polymer-iron oxide hybrid nanofibers: electrospun filtration devices for metal oxyanion removal. Water Research 2017;117:207-217. R835177 (Final)
  • Abstract from PubMed
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Peter KT, Myungb NV, Cwiertny DM. Surfactant-assisted fabrication of porous polymeric nanofibers with surface-enriched iron oxide nanoparticles:composite filtration materials for removal of metal cations. Environmental Science: Nano 2018;5:669-681. R835177 (Final)
  • Abstract: RSC-Abstract
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  • Supplemental Keywords:

    Decentralized treatment, point of use treatment, nanotechnology, water reuse, catalysis, water treatment, wastewater treatment, water treatment system, nanofiber filters  

    Progress and Final Reports:

    Original Abstract
  • 2012 Progress Report
  • 2013 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report