Characterization of nanobubbles & effectiveness in breakdown of organic micropollutants
Authors
Lütken, Victor ; Petersen, Andreas Rasmus
Term
4. Term
Education
Publication year
2024
Submitted on
2024-06-02
Pages
73
Abstract
Denne afhandling undersøger, om nanobobler kan bidrage til at fjerne organiske mikroforureninger enten ved at fremme kemisk nedbrydning eller ved at påvirke membranfiltrering. Luft-, CO2- og O2-nanobobler blev genereret og karakteriseret ved målinger af størrelse og zeta-potentiale før og efter påvirkning med syre, ultralyd og UV-lys i nærvær af benzoesyre. Opløst gasindhold blev målt for at vurdere, om boblerne gik i opløsning ved påvirkningerne, og boblernes stabilitet over tid blev undersøgt. Derudover blev effekten af nanobobler på nedbrydning af benzoesyre under syre, ultralyd og UV-lys testet, samt om nanobobler påvirker membraners tilbageholdelse af organiske mikroforureninger. Resultaterne viste en generel størrelsesstigning for O2- og luft-nanobobler ved alle påvirkninger, mens CO2-nanobobler blev mindre ved ultralyd og viste en mindre størrelsesstigning ved syre. Zeta-potentialet udviste ingen samlet trend, bortset fra at syre konsekvent øgede det målte zeta-potentiale. Der kunne ikke påvises en sammenhæng mellem opløst gas og boblers opløsning, og stabiliteten over tid var kortest for CO2-nanobobler, længere for luft og længst for O2. Nanobobler gav ingen målbar effekt på nedbrydningen af benzoesyre under de testede forhold. I membranforsøg havde nanobobler enten ingen indflydelse på gennemtrængningen af organiske mikroforureninger eller medførte øget passage, hvilket indikerer, at nanobobler ikke forbedrede tilbageholdelsen under de undersøgte betingelser.
This thesis examines whether nanobubbles can aid the removal of organic micropollutants by promoting chemical breakdown or influencing membrane filtration. Air-, CO2-, and O2-filled nanobubbles were generated and characterized by measuring size and zeta potential before and after exposure to acid, ultrasound, and UV light in the presence of benzoic acid. Dissolved gas was monitored to assess whether bubbles dissolved during these treatments, and time-dependent stability was evaluated. The effect of nanobubbles on benzoic acid degradation under acid, ultrasound, and UV exposure was tested, and their influence on membrane retention of organic micropollutants was assessed. Results showed a general increase in size for O2 and air nanobubbles across treatments, while CO2 nanobubbles decreased in size under ultrasound and showed a small increase under acid. Zeta potential exhibited no overall trend except that acid consistently increased the measured zeta potential. No correlation between dissolved gas content and bubble dissolution was found, and stability was shortest for CO2 nanobubbles, followed by air, with O2 being most stable. Nanobubbles had no measurable effect on benzoic acid breakdown under the tested conditions. In membrane experiments, nanobubbles either had no effect on organic micropollutant passage or increased it, indicating no improvement in retention under the examined conditions.
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