KJEMI nr. 5 - 2022

K J E M I 5 2 0 2 2 2 7 Doktogradsdisputaser MSC. MAJA NIPENVED, Kjemisk institutt, UiO, har disputert for Ph.d.-graden med avhandlingen «Spatial and temporal trends of anthropogenic pollutants in a tropical, urban environment in East Africa». Sammendrag Mennesker og miljø i det Globale Sør kan være spesielt utsatt for miljøgifter som en konsekvens av manglende ressurser til miljøvennlig håndtering av avfall i kombinasjon med økende folketall og forbruk. I dette arbeidet har romlige trender og tidstrender av noen utvalgte miljøgifter blitt undersøkt i og rundt en av Øst-Afrikas største byer, Dar es Salaam, Tanzania. Main research findings A range of chemicals which are potentially harmful to human health and the environment are used in industrial and consumer products including electronics. Source regions for such pollutants to the environment may be shifting from the Global North to the Global South given e.g., trade in products and waste and lacking capacity for environmentally sound waste handling. However, there are large knowledge gaps concerning the occurrence and fate of these chemicals in the Global South. In this work, occurrence, distribution, sources, and time trends of both legacy and emerging chemical pollutants were investigated in and around Dar es Salaam, Tanzania. This was done by analysis of samples from air and soil, and a dated sediment core. The results from the dated sediment core showed increasing levels of legacy chemical pollutants in the late 2010s. This suggests that international regulation has not yet been effective in lowering environmental burdens of these pollutants in Dar es Salaam. Levels of some emerging chemical pollutants were documented to increase dramatically in the late 2010s. Spatial trends of these emerging chemical pollutants in air and soil in the studied region suggests handling of both general waste and electronic waste are important sources. MSC. WEN TAN, ved Kjemisk institutt, UiO, har disputert for Ph.d.-graden med avhandlingen «The Atmospheric Fate of Selected Amines Emitted from Carbon Capture Facilities». Sammendrag I avhandlingen sin har kandidaten undersøkt miljøpåvirkningen av kjemiske forbindelser som slippes ut i atmosfæren fra karbonfangstanlegg. Main research findings The climate crisis necessitates urgent decarbonisation, which can only be achieved through a variety of technologies and solutions. One of them is the chemical capture of CO2 released from industrial point sources and its storage in subsea formations. On an industrial scale, CO2 is currently captured via reaction with amines, which are small organic molecules that «bind» the CO2 in the flue gas and thereby prevent it from entering the atmosphere. However, in this process trace amounts of amines are released into the atmosphere, where they can form particles and other air pollutants (e.g., nitrosamines) that are harmful to human health and the environment. In my work, I have initially explored the capability of an ultra-sensitive mass spectrometer to detect traces of amines in the atmosphere. I have furthermore studied the degradation of three amines (tert-butylamine, 2-Amino-2-methyl-1-propanol, and piperazine) under simulated atmospheric conditions in a large outdoor chamber. The products formed during atmospheric degradation were investigated using state-of-the-art theoretical and experimental methods. One of the main findings was that amines very efficiently form particles in the atmosphere. I have, for the first time, used an advanced mass spectrometer to characterize the chemical composition of the particles formed from the breakdown of amines. MSC. ISABELLE GERZ, ved Kjemisk institutt, UiO, har disputert for Ph.d.-graden med avhandlingen «Bioinspired Copper Complexes for Incorporation into UiO-67». Sammendrag Avhandlingen beskriver syntese og spektroskopiske studier av kobberkomplekser. Noen av kompleksene har blitt inkorporert i metallorganiske rammeverk. Målet med dette er å lage et materiale som minner om inspirasjonskilden sin fra naturen, et enzymatisk aktivt sete. Main research findings Methanol may play a central role as a fuel in the future. It can be generated from natural gas, methane, by oxidising one of its four C-H bonds. However, one easily oxidises it all the way- commonly referred to as burning. The current methods are energy consuming, calling for improved ways to perform the reaction. Ideally, the green-house gas methane is oxidised with oxygen from the air. A great teacher on how to control the degree of oxidation is nature. A class of copper-based enzymes is capable of selective C-H bond oxidation. In this thesis, artificial copper complexes were made that carry structural aspects of the enzyme. In addition to developing recipes for making these complexes, the work investigated how they interact with themselves. In solution, one of the complexes could be found alone, in pairs or in bigger groups. Some of the complexes reacted with oxygen, which made them change colour from brown to green or from yellow to red. Both colour changes were found to originate from oxidation of copper, the first step of the intended process. Preliminary tests with another hydrocarbon, cyclohexane, showed that the complexes were capable to oxidise C-H bonds. ●

RkJQdWJsaXNoZXIy MTQ3Mzgy