| Over 1 billion people worldwide lack access to safe drinking water and 5,000 people die each day due to drinking contaminated water. With the development of new industries, new substances and chemicals are entering the waters every day, and the current water treatment processes are unable to remove them entirely. For example, agriculture is the world's heaviest consumer of water, and nitrates and nitrites from fertilizers are washed away with the water to rivers and streams. These chemicals can cause problems to humans and to the environment. To humans, they can cause methemoglobinemia, also known as "blue baby syndrome". To the environment, they can cause eutrophication, a phenomenon greatly reduced the dissolved oxygen content of the water harming the aquatic animals.;Catalytic remediation of water is a promising strategy to meet the ecological, social and economic demands of the future, but the high-cost of developing new catalysts for wastewater treatment applications often limits their adoption in new wastewater treatment processes.;In this work, we investigate nitrate and nitrite reduction over spherically shaped gold-based catalysts. Starting with Au13 we can modify composition by replacing just one or two atoms with other metals, forming Au12X and Au11XY clusters. Here, X/Y = Fe, Pd, In, and Cu, which were chosen because they cover a large range of groups in the periodic table, are relatively inexpensive, and are non-toxic. All of the tested catalysts tested show favorable behavior for nitrate reduction but not for nitrite reduction. We find that X,Y = Fe, Pd show the best results for nitrite dissociation because of the exothermic behavior towards both reactions. We also compute ammonia and water dissociation energies on the catalyst surfaces to determine if the catalysts will dissociate these species.;This work provides the essential framework for modeling pollutant remediation in water. The methods described in this thesis were used to screen a range of catalysts compositions and identify small group of catalysts that performs the desired reactions selectively over water and organic matter. |
