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" Fate of Nanomaterials in the Environment: Effects of Particle Size, Capping Agent and Surface Cleaning Products on the Stability of Silver Nanomaterials In Colloidal Consumer Products "
Radwan, Islam Mohamed Othman
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Latin Dissertation
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English
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| Record Number
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1052817
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TL51934
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| Main Entry
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Radwan, Islam Mohamed Othman
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| Title & Author
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Fate of Nanomaterials in the Environment: Effects of Particle Size, Capping Agent and Surface Cleaning Products on the Stability of Silver Nanomaterials In Colloidal Consumer Products\ Radwan, Islam Mohamed Othman
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| College
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University of Cincinnati
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| Date
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2019
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| Degree
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Ph.D.
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2019
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| Note
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170 p.
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| Abstract
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Nanotechnology is one of the most prospective technologies of this century and promises groundbreaking innovation in many fields due to the unique physicochemical characteristics of engineered nanomaterials (ENMs). The potential impacts of ENMs on aquatic environments and humans currently receive significant attention by both regulators and academia. Currently, approximately a quarter of all nano-enabled consumer products (CPs) contain silver nanoparticles (AgNPs). AgNPs are incorporated into a wide range of CPs (e. g., textiles, disinfectants, household appliances, industrial, medical, and scientific applications). The increased application of AgNPs will inevitably lead to their release into environmental systems. Therefore, the investigation and quantification of AgNPs in environmental matrices becomes critical to answer questions regarding their fate/transport and potential risks to the environment and human health. This dissertation aims to systematically explore the release of AgNPs in various environmental media. Also, this research work will aid in developing a rapid and sensitive approach for quantification of AgNPs-CPs in various matrices. First, the silver-containing nanoparticles were characterized in 22 consumer products that advertised the use of silver or colloidal silver as the active ingredient. A high degree of variability between measured and claimed values for total silver was detected. Primary silver particle size distributions by transmission electron microscopy showed two categories of particles - smaller particles (<5 nm) and larger particles (20-40 nm). This characterization study helps us to understand the potential human exposure risks posed by these CPs. Second, the dissolution trends of colloidal AgNPs in five products were investigated in deionized and tap water. These five CPs were selected from the characterization study. To expand our understanding on the fundamental mechanisms of dissolution of AgNPs in CPs, the dissolution behavior of AgNPs in various CPs was compared to well-characterized laboratory-synthesized AgNPs. We designed an experimental system where the capping agent and the total AgNP surface area in suspensions were the primary contributors to the dissolution trends by controlling the initial particle size and dissolution media. There were small differences in the dissolved masses of Ag+ between products, but we did not observe any significant differences in the dissolution trends obtained for deionized and tap water. All AgNP suspensions were shown to have the potential to persist as nanoparticles in aquous matrices for up to one month. This finding indicates AgNPs could lead to longer lifetime or increased transport in the environment. Third, a study of exposure between three differently-charged surface cleaning products and AgNPs was conducted to better understand the transformation and environmental impacts of AgNPs. Changes in size, morphology, color, and chemical composition were detected during a 60 min exposure. The implication of these changes could mean altered antimicrobial activity, user exposure, and transportation in the environment. Surface cleaning products were also exposed to Ag+ as AgNO3 to simulate Ag+ released from solid nano-enabled products. Overall, this dissertation provides insights for the development of a rapid and sensitive approach for quantification of AgNPs-CPs in various matrices, which can be further leveraged for studies on the fate, transport, and ecotoxicity of the AgNPs.
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Environmental engineering
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University of Cincinnati
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