Chemical Controls over Natural Organic Matter Aggregation and the Resulting Structures

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Natural organic matter (NOM), a diverse collection of organic chemical entities derived from the natural decay of biomass in the environment, is ubiquitous in most ecosystems. NOM is known to develop strong interactions with certain heavy metal ions, anions, and small organics (e.g. pharmaceuticals), making an understanding of NOM behavior in solution essential to developing models of how organic and inorganic pollutants move through the environment. However, the structure of NOM in solution and how chemical conditions affect that structure are poorly understood, as are the ways in which chemical conditions affect the interaction of NOM with other NOM molecules, surfaces, and ions. Some metal ions are known to promote the aggregation or flocculation of NOM in solution to produce particles consisting of many molecules. Flocculation is the process by which individual molecules interact strongly with one another to form large particles visible with the naked eye that can settle from solution via gravitational forces. Aggregation is similar, however, a particle aggregate is generally smaller and can remain suspended in solution under the influence of only gravity. This thesis attempts to shed light on the specific types of molecular-scale interactions between NOM molecules, solvent molecules, and other components of the solution; how floccs and aggregates form and grow; and how chemical properties of the NOM, mineral surfaces, and the solution phase affect aggregation/flocculation and the properties of the resulting aggregate or flocc particles.
Thesis completed in partial fulfillment of the requirements for the Alfred University Honors Program.
Honors thesis, Chemistry, Natural organic matter, Molecular scale interactions