Synthesis and characterization of single-walled carbon nanotubes for use in water purification

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Johnson, B. (2016). Synthesis and characterization of single-walled carbon nanotubes for use in water purification. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

As human health concerns over disinfection byproducts (DBPs) in drinking water increase, so does the need to development new materials that remove them rapidly and at high-efficiency. Ion exchange (IEX) is an effective method for the removal of natural organic matter (NOM), especially anion exchange resins (AERs) with quaternary ammonium functional groups. However, capacity is limited in existing commercial resin materials because adsorbates can only interact with the outermost surface area, which makes these products inefficient on a mass basis. We have synthesized a novel "NanoResin" exploiting the enhanced NOM removal of the quaternary ammonium resin while utilizing the immense surface area of single-walled carbon nanotubes (SWCNTs), which act as scaffolding for the resin. Our nanomaterials show increased adsorption capacity per gram compared to commercially available adsorbents and reach equilibrium in a fraction of the time. This NanoResin requires only about 10 seconds to reach ion-exchange equilibrium versus more than 30 minutes for commercial resins because kinetics are only limited by diffusion. Using NanoResin as a thin film membrane filter, a NOM surrogate was removed to below its detection limit within 10 seconds of contact. Comparatively, commercial AERs only achieved partial removal after more than 15 minutes. High-capacity adsorption of a low molecular weight (MW) surrogate has been measured. NOM removal was demonstrated in solutions of both low and high specific UV absorbance (SUVA; the absorbance at 254 nm divided by dissolved organic carbon concentration) composition with these nanomaterials. Additionally, the NanoResin showed increased removal over commercial resins with a NOM concentrate sample taken from Myrtle Beach, SC, demonstrating NanoResin is an effective method of removal for refractory NOM in a natural aqueous environment. Synthesis and characterization of the polymers and nanomaterials are presented in the following thesis, along with a thorough description of the atom transfer radical polymerization (ATRP) mechanism. We measured and characterized the adsorption capacity, adsorption kinetics, and the regeneration and reusability of these new materials for surrogate and natural NOM. The open matrix microstructure of this NanoResin precludes any intraparticle diffusion of adsorbates. Therefore the rate of adsorption is limited only by solvent diffusion to the NanoResin surface. Thus, these nanomaterials act as a "contact resin."

Details
Author

Johnson, Billy

Title

Synthesis and characterization of single-walled carbon nanotubes for use in water purification

Physical Description

1 online resource (125 pages) : PDF

Date

2016

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

As human health concerns over disinfection byproducts (DBPs) in drinking water increase, so does the need to development new materials that remove them rapidly and at high-efficiency. Ion exchange (IEX) is an effective method for the removal of natural organic matter (NOM), especially anion exchange resins (AERs) with quaternary ammonium functional groups. However, capacity is limited in existing commercial resin materials because adsorbates can only interact with the outermost surface area, which makes these products inefficient on a mass basis. We have synthesized a novel "NanoResin" exploiting the enhanced NOM removal of the quaternary ammonium resin while utilizing the immense surface area of single-walled carbon nanotubes (SWCNTs), which act as scaffolding for the resin. Our nanomaterials show increased adsorption capacity per gram compared to commercially available adsorbents and reach equilibrium in a fraction of the time. This NanoResin requires only about 10 seconds to reach ion-exchange equilibrium versus more than 30 minutes for commercial resins because kinetics are only limited by diffusion. Using NanoResin as a thin film membrane filter, a NOM surrogate was removed to below its detection limit within 10 seconds of contact. Comparatively, commercial AERs only achieved partial removal after more than 15 minutes. High-capacity adsorption of a low molecular weight (MW) surrogate has been measured. NOM removal was demonstrated in solutions of both low and high specific UV absorbance (SUVA; the absorbance at 254 nm divided by dissolved organic carbon concentration) composition with these nanomaterials. Additionally, the NanoResin showed increased removal over commercial resins with a NOM concentrate sample taken from Myrtle Beach, SC, demonstrating NanoResin is an effective method of removal for refractory NOM in a natural aqueous environment. Synthesis and characterization of the polymers and nanomaterials are presented in the following thesis, along with a thorough description of the atom transfer radical polymerization (ATRP) mechanism. We measured and characterized the adsorption capacity, adsorption kinetics, and the regeneration and reusability of these new materials for surrogate and natural NOM. The open matrix microstructure of this NanoResin precludes any intraparticle diffusion of adsorbates. Therefore the rate of adsorption is limited only by solvent diffusion to the NanoResin surface. Thus, these nanomaterials act as a "contact resin."

Genre

masters theses

Subjects--Topics

Materials science
Nanoscience
Chemistry

Degree

M.S.

Keywords

Carbon Nanotubes
Nanoscale Anion Exchange Resin
Water Purification

Subject Area

Chemistry

Advisor(s)

Poler, Jordan

Committee Members

Amburgey, James
Ogle, Craig
Schmedake, Thomas

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2016.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Johnson_uncc_0694N_11168

Permalink

http://hdl.handle.net/20.500.13093/etd:773