Ion-exchange materials are an important area of research because of their applications for water purification and metal extraction. Metal-organic frameworks (MOFs) are attractive candidates for ion-exchange materials due to their high surface area and the variety of potential modifications to the linkers. In this project, conducted at the National University of Singapore, the zirconium (IV) MOF UiO-66-NH2 was modified using a mild two-step process to form a MOF with quaternary ammonium moieties. Framework characterization using gas sorption and x-ray diffraction indicated that the modification caused was successful, indicated by the retained high crystallinity and decreased surface area. NMR indicated that a total of 20% amine groups had been transformed to quaternary ammonium balanced by iodide ions. Anion-exchange experiments were carried out to evaluate the quaternized MOF's ability to extract tetrachloroaurate (III) (AuCl4-) from aqueous solution. However, both the modified and unmodified MOF caused a rapid decrease in the concentration of the anion as indicated by the UV-vis spectrum, which could be attributed to the amines in the MOF reducing Au3+ to Au0. The pristine UiO-66-NH2 caused a more rapid decrease in AuCl4- concentration, possibly due to the higher porosity of the unmodified framework and higher reduction activity of primary amines. Aside from conducting research, I also spent the summer expanding my horizons by visiting several other countries in Southeast Asia, where I visited incredible temples, ate delicious food, and interacted with fascinating cultures.

MOFs to mee soto: A summer at the National University of Singapore

253rd National Meeting (2017)

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