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Wilfrid Laurier University Faculty of Science
July 1, 2015

Canadian Excellence

Jim Mathers, Honours Chemistry, 2005


Jim Mathers Thesis Abstract

Development of Improved Aluminum-Based Coagulants for Drinking Water Treatment: Testing the Al3018+ Cation

Toxic halogenated organics can result during drinking water treatment. To minimize halogenated organics in drinking water dissolved organic carbon must be removed during drinking water treatment before chlorination. Substances that remove organic matter by creating flocs big enough to settle or filter are called flocculants or coagulants. Typical flocculants include aluminum and iron salts. Improved coagulants are theoretically possible using metal polycations. The Al30 complex: [Al30O8(OH)56(H2O)24]18+ was tested as a flocculant for the removal of organic material in wastewater treatment. Comparative analysis of Al30 was performed against Al3+ and Al13: [Al13O4(OH)24(H2O)12]7+, which are both currently used for such applications in wastewater treatment, in order to test the expected result that Al30 is more effective at removing dissolved organic carbon (DOC). Al13 and Al30 were successfully synthesized from aluminum nitrate and confirmed using 27Al-NMR and spectrophotometric analysis was used to determine that the Al13 sample contained 70 % polymeric aluminum and the Al30 sample contained 72 % polymeric aluminum. Batch tests on the reaction of each flocculant with a model organic involved spectrophotometric analysis and filtration to compare removal of DOC removed by each flocculant. It was shown that Al13 was significantly more efficient than Al3+ at removal of DOC, and that Al30 was better still.

Kara Noland Thesis Abstract:

Mineral-mineral and mineral-bacteria surface interactions determined using proton binding affinities

The surfaces of crystals such as goethite (FeOOH), hematite (Fe2O3) and titanium oxide (TiO2) can be characterized by proton affinity on their reactive surfaces. Acid base titrations are a useful tool in determining the structure and reactivity of natural sorbents. The proton affinity measured via an acid base titration, determines the type of oxygen functional group present on the surface of the mineral. pKa values are experimentally determined and assigned using the Fully Optimized Continuous (FOCUS) pKa spectrum. FOCUS analysis yields an optimal answer for both goodness of fit and smoothness in analyzing the data obtained. (Smith et al. Environ.Sci.Technol. 2001) Specific surface reactions are assigned to each pKa value based on the MUSIC model, a theoretical model that is used to determine pKa values for defined crystal structures. (Heimstra et al. J. Coll. Sci. 1996) Using the MUSIC model, the pKa values are used to assign crystal-face-specific functional group identities on the surface of the crystal. Mixtures of crystals and bacteria can be analyzed in the same manner and associations between solid phases inferred from changes in pKa values of mixtures compared to the end-members.