Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Chemistry

Program Name/Specialization

Biological and Chemical Sciences

Faculty/School

Faculty of Science

First Advisor

Scott Smith

Advisor Role

Supervisor

Abstract

Phosphorus, iron oxides, and dissolved organic matter (DOM) are components present in all aquatic systems. Excess amounts of phosphorus in aquatic systems have the potential for toxic effects, in particular, contributing to eutrophication. Most of the previous studies performed looked at the surface complexation of inorganic phosphate anions (P) to mineral surfaces such as hydrous ferric oxide (HFO). However, the role of DOM on the interactions between HFO and P is unknown. This study investigates the influence of DOM on the surface complexation of P onto HFO surfaces. Moreover, this study looks at the possibility of cation bridging formation (Ca 2+, Mg2+) between HFO, P, and DOM. In laboratory experiments, iron salts were added to several synthetic waters containing different electrolyte concentrations, P, and DOM. During these experiments, P removal was measured as a function of DOM concentrations, DOM sources, pH, and Fe: P molar ratio. The dissolved organic model compounds were collected from various sites and characterized using fluorescence excitation-emission and total organic carbon (TOC) measurement. The results indicated that DOM sources that contain more proteinaceous materials enhanced P adsorption into HFO. These sources show a potential of direct binding between P and DOM on the HFO surface. Also, the adsorption of P improved in the presence of higher concentrations of Ca2+ and Mg2+. This work demonstrates that, for the conditions studied, organic matter does not tend to inhibit phosphate adsorption to HFO, although the specific mechanism of interaction may be different in the presence of organic matter and may include bridge bonding arrangements.

Convocation Year

2022

Convocation Season

Spring

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