Point-of-use Drinking Water Purification: Chromium(VI) Capture and Beyond

Millions of people around the world are at risk of exposure to polluted water. According to the United Nations, unsafe water claims more lives each year than all forms of violence put together. Particularly in developing countries, where the population has no access to centrally treated tap water, point-of-use water purification techniques are important to mitigate the risks of consuming ground- or surface waters. Many such techniques already exist and are in use today, but they mostly target bacteria and macroscopic contaminations that can be removed due to size. Dissolved ions are significantly more difficult to remove, especially because they can be harmful even at extremely low concentrations. Some of the most dangerous heavy metals polluting drinking water around the world today are chromium, arsenic, and lead. In this thesis I first highlight the impact of these pollutants before presenting filter materials I synthesized that can efficiently remove chromium(VI) oxoanions from drinking water. By attaching functional molecules such as a dimethylaminomethyl-calixarene and N-butylimidazole to non-woven cloth via a pulsed plasma polymer linker layer, I created filters that can capture chromium(VI) at neutral pH, from solutions with low starting concentrations, in the presence of competitive anions, and even from real wastewater samples. Moreover, these filters can be easily recycled many times. In the last results chapter, I present new findings regarding the epitaxial growth mechanism of the metal–organic framework MOF-508. These materials are attractive candidates for filtration applications due to their vast internal surface. The discovery that they can be grown on untreated polymer surfaces, as well as the presented method for simple MOF film transfer, can aid future developments in this field.