Date of Degree
PhD (Doctor of Philosophy)
Civil and Environmental Engineering
Cwiertny, David M
First Committee Member
Parkin, Gene F
Second Committee Member
Just, Craig L
Third Committee Member
Forbes, Tori Z
Fourth Committee Member
Guymon, C Allan
A range of chemical pollutants now contaminate drinking water sources and present a public health concern, including organic compounds, such as pharmaceuticals and pesticides, and both metalloids and heavy metals, such as arsenic and lead. Metalloids and heavy metals have been detected in private drinking water wells, which do not fall under federal drinking water regulations, as well as in urban tap water, due to the introduction of contamination to the drinking water distribution system. Further, many so-called “emerging organic contaminants,” which are present in drinking water sources at detectable levels but have unknown long-term health implications, do not fall under federal drinking water regulations. To protect the health of consumers, drinking water treatment at the point-of-use (POU) (i.e., the tap) is essential. Next-generation POU treatment technologies must require minimal energy inputs, be simple enough to permit broad application among different users, and be easily adaptable for removal of a wide range of pollutants.
Nanomaterials, such as carbon nanotubes and iron oxide nanoparticles, are ideal candidates for next-generation drinking water treatment, as they exhibit unique, high reactivity and necessitate small treatment units. However, concerns regarding water pressure requirements and nanomaterial release into the treated supply limit their application in traditional reactor designs. To bridge the gap between potential and practical application of nanomaterials, this study utilizes electrospinning to fabricate composite nanofiber filters that effectively deploy nanomaterials in drinking water treatment. In electrospinning, a high voltage draws a polymer precursor solution (which can contain nanomaterial additives, in the case of nanocomposites) from a needle to deposit a non-woven nanofiber filter on a collector surface.
Using electrospinning, we develop an optimized, macroporous carbon nanotube-carbon nanofiber composite that utilizes the sorption capacity of embedded carbon nanotubes, and achieves a key balance between material strength and reactivity towards organic pollutants. Additionally, via single-pot syntheses, we develop two optimized polymer-iron oxide composites for removal of heavy metal contamination by inclusion of iron oxide nanoparticles and either cationic or anionic surfactants in the electrospinning precursor solution. In hybrid materials that contain a well-retained quaternary ammonium surfactant (tetrabutylammonium bromide) and iron oxide nanoparticles, ion exchange sites and iron oxide sites are selective for chromate and arsenate removal, respectively. We demonstrated that a sulfonate surfactant, sodium dodecyl sulfate, acted as a removable porogen and an agent for surface segregation of iron oxide nanoparticles, thus enhancing composite performance for removal of lead, copper, and cadmium. Notably, nanoparticles embedded in composites exhibited comparable activity to freely dispersed nanoparticles. Collectively, the composites developed in this work represent a substantial advance towards the overlap of effective nanomaterial immobilization and utilization of nanomaterial reactivity. Outcomes of this work advance current knowledge of nanocomposite fabrication, and contribute to the responsible and effective deployment of nanomaterials in POU drinking water treatment.
A range of chemical pollutants is present in drinking water sources, including organic compounds, (e.g., pharmaceuticals and pesticides) and heavy metals (e.g., arsenic and lead). To protect the health of consumers, particularly those with private drinking water wells and in urban areas with aging water distribution systems, drinking water treatment at the point of use (POU) is essential. Next-generation POU technologies must require minimal energy, efficiently remove a range of pollutants, and be simple enough to permit broad application across users. Nanomaterials are ideal candidates for such technologies, as they exhibit high reactivity within small physical footprints. However, concerns regarding pressure requirements and material release challenge their application in traditional reactor designs. To bridge the gap between potential and practical application of nanomaterials, this study utilizes electrospinning to fabricate composite nanofiber filters. In electrospinning, a high voltage draws a polymer precursor solution (which can contain nanomaterial additives) from a needle, depositing a non-woven nanofiber filter on a collector. Using electrospinning, we develop an optimized carbon nanotube-carbon nanofiber composite that achieves a key balance between material strength and reactivity towards organic pollutants. Additionally, we develop two optimized polymer nanocomposites with embedded iron oxide nanoparticles and/or ion exchange groups, and demonstrate their application for removal of a range of metal contaminants (e.g., arsenic, chromium, lead, copper, and cadmium). Outcomes of this work establish novel methods for nanocomposite fabrication, contributing to the responsible and effective deployment of nanomaterials in POU drinking water treatment.
electrospinning, heavy metals, nanocomposite, organic micropollutants, point-of-use, water treatment
xxv, 287 pages
Includes bibliographical references (pages 261-287).
Copyright © 2016 Katherine T. Peter
Peter, Katherine T.. "Development of electrospun nanofiber composites for point-of-use water treatment." PhD (Doctor of Philosophy) thesis, University of Iowa, 2016.