DOI

10.17077/etd.7mcurnb9

Document Type

Dissertation

Date of Degree

Summer 2018

Access Restrictions

Access restricted until 08/31/2019

Degree Name

PhD (Doctor of Philosophy)

Degree In

Chemistry

First Advisor

Sarah C. Larsen

Second Advisor

Vicki H. Grassian

First Committee Member

Edward G. Gillan

Second Committee Member

Johna Leddy

Third Committee Member

Mark A. Young

Abstract

Nanoparticles have gained growing attention of the scientific community over the past few decades due to their high potential to be used in diverse industrial applications. Nanoparticles often possess superior characteristics, such as catalytic activity, photochemical activity, and mechanical strength, compared to their bulk counterparts, making them more desirable in different industrial applications. During the past few decades, the use of the nanoparticles in various industries has been increased. With increasing usage release of nanoparticles into the environment has also increased. There is a growing concern about the nanoparticle toxicity and numerous studies have shown the toxic effects of different nanoparticles on various plants, animals, and microorganisms in the environment. Toxicity of nanoparticles is often attributed to their morphology and their ability to undergo different transformations in the environment. These transformations include aggregation, dissolution, and surface adsorption.

Natural organic matter (NOM) are the most abundant natural ligands in the environment which include Humic acid and Fulvic acid. These high molecular weight organic molecules have complex structures and contain many different functional groups such as carboxylic acid groups, hydroxyl, amino and phenolic groups that can interact with the nanoparticle surface. The nature and the intensity of the interaction are dependent on several factors including the size and the surface functionality of nanoparticles and pH of the medium. The smaller the nanoparticle, the higher the adsorption of NOM due to the high surface to volume ratio of smaller particles. Functional groups on the surface dictate the surface charge of the nanoparticles in water depending on the acidity. The higher the acidity, higher the adsorption of NOM due to increased electrostatic attractions between positively charged nanoparticles and the negatively charged NOM molecules. Adsorbed NOM on nanoparticles affect the other transformations such as aggregation and dissolution and can in turn alter the reactivity and toxicity of the nanoparticles. Therefore, effect of NOM is an important factor that should be considered in environmental toxicity related studies of nanoparticles.

Keywords

Agglomeration, Engineered Nanoparticles, Nanoparticle Transformations, Natural Organic Matter, Surface Adsorption, TiO2

Pages

xiv, 92 pages

Bibliography

Includes bibliographical references (pages 83-92).

Copyright

Copyright © 2018 Sanjaya Dilantha Jayalath Mudiyanselage

Available for download on Saturday, August 31, 2019

Included in

Chemistry Commons

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