University of Iowa Iowa Research Online Theses and Dissertations Fall 2016 Development of electrospun nanofiber composites for point-of- use water treatment Katherine T. Peter University of Iowa Follow this and additional works at: https://ir.uiowa.edu/etd Part of the Civil and Environmental Engineering Commons Copyright © 2016 Katherine T. Peter This dissertation is available at Iowa Research Online: https://ir.uiowa.edu/etd/2259 Recommended Citation Peter, Katherine T.. "Development of electrospun nanofiber composites for point-of-use water treatment." PhD (Doctor of Philosophy) thesis, University of Iowa, 2016. https://doi.org/10.17077/etd.ga58rdni Follow this and additional works at: https://ir.uiowa.edu/etd Part of the Civil and Environmental Engineering Commons DEVELOPMENT OF ELECTROSPUN NANOFIBER COMPOSITES FOR POINT- OF-USE WATER TREATMENT by Katherine T. Peter A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Civil and Environmental Engineering in the Graduate College of The University of Iowa December 2016 Thesis Supervisor: Associate Professor David M. Cwiertny Copyright by KATHERINE T. PETER 2016 All Rights Reserved Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL ____________________________ PH.D. THESIS _________________ This is to certify that the Ph.D. thesis of Katherine T. Peter has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Civil and Environmental Engineering at the December 2016 graduation. Thesis Committee: ____________________________________________ David M. Cwiertny, Thesis Supervisor ____________________________________________ Gene F. Parkin ____________________________________________ Craig L. Just ____________________________________________ Tori Z. Forbes ____________________________________________ C. Allan Guymon To my parents, thank you for your love and support. ii ACKNOWLEDGEMENTS I would like to thank my advisor, David Cwiertny, for his support, encouragement, and advice. Your enthusiasm is contagious, and I am truly grateful for your mentorship and the opportunity to work with you. To my lab mates and colleagues, Jiajie Qian, Katie Greenstein, Edgard Verdugo, Brandon Jennings, Nick Pflug, Kathryn Klarich, Jason Haase, Kyle Nelson, Matt Nagorzanski, and AJ Johns – thank you for your friendship, assistance, and laughter. You made our lab a fun and interesting place to work. Thank you to our collaborators at the University of Illinois Urbana Champaign, Helen Nyugen and Ruiqing Lu, for their contributions to this work. I look forward to continuing collaborations. Thank you also to Marty St. Clair and Susan Noreuil at Coe College, for your assistance and the indispensable use of your ICP-OES. I am immensely grateful to the National Science Foundation for funding my graduate career. It was an honor to be a Graduate Research Fellow. A thank you as well to the EPA for funding this research. I would like to extend my gratitude to my undergraduate advisors, Dr. John Fortner and Dr. Jay Turner, who fostered my interest in research, provided essential mentoring and advice, and encouraged me to attend graduate school. Thank you for helping me find the right path. I owe a big thank you to the wonderful folks at Iowa Valley Habitat for Humanity. You inspired me every week, and made me feel truly a part of this community. Of course, a huge thank you to my friends and family. Kate – thanks for being my roommate, even from four hours away. Your friendship and support mean the world iii to me. Eric – thanks for supporting me through both college and grad school, and for being a great big brother. Mom and Dad – thanks for your love and encouragement, for always being a phone call away, and for all the wonderful snail mail. I appreciate you and everything you have done for me, more than words can express. Jason, thank you for being my rock and my best friend, for spending countless hours in cars and planes to visit Iowa and travel with me, and for your unconditional love and support. I am lucky to have you by my side. iv ABSTRACT 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 v 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. vi PUBLIC ABSTRACT 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. vii TABLE OF CONTENTS LIST OF TABLES ............................................................................................................. xi LIST OF FIGURES .........................................................................................................