Cryo-SEM visualization of bulk nanobubbles in aqueous solutions

Patounas, Evangelos; Πατούνας, Ευάγγελος

dc.contributor.author	Patounas, Evangelos	en
dc.contributor.author	Πατούνας, Ευάγγελος	el
dc.date.accessioned	2020-10-26T15:01:45Z
dc.date.available	2020-10-26T15:01:45Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/51633
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.19331
dc.rights	Αναφορά Δημιουργού-Μη Εμπορική Χρήση 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc/3.0/gr/	*
dc.subject	Νανοφυσαλλίδες	el
dc.subject	Μικροσκοπία	el
dc.subject	Οπτικοποίηση	el
dc.subject	Ψύξη	el
dc.subject	Nanobubbles	en
dc.subject	Kρυογενικές συνθήκες	el
dc.subject	Cryogenic conditions	en
dc.subject	Cryo-SEM	en
dc.subject	Freezing	en
dc.subject	Bulk	en
dc.title	Cryo-SEM visualization of bulk nanobubbles in aqueous solutions	en
heal.type	bachelorThesis
heal.classification	Materials science	en
heal.language	el
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2020-10-21
heal.abstract	The objective of this diploma thesis is to identify nanobubbles present in bulk solutions, with regard to their morphology and size, by implementing cryo-SEM measurements. Particularly, aqueous samples containing O2 and N2 bulk nanobubbles in pure water and pure water blended with magnetic ionic liquid, that are produced with hydrodynamic cavitation in the Materials & Membranes for Environmental Separations Laboratory of NCSR “Demokritos” were visualized by applying cryo scanning electron microscopy (cryo-SEM). This is the first study where the technique of cryo-SEM is applied for the observation of bulk nanobubbles in aqueous solutions. Cryo-SEM enables high-resolution and preservation of the morphology of the initial sample, as the sample is abruptly frozen in a manner that retains the structure of its contents. In the case of this study, rapid freezing was performed with liquid nitrogen both at ambient pressure and at high-pressure of 2000 bar. Subsequently, cryo-SEM imaging was applied, analysis was performed, and conclusions were extracted from the visualization regarding the size and morphology of the bulk nanobubbles present in the samples. Spherical formations attributed to oxygen NBs were observed in pure water and pure water blended with magnetic ionic liquid after preliminary freezing both at ambient pressure and high pressure (2000 bar). However, nitrogen nanobubbles could not be identified. The influence of pressure and the formation of ice during the freezing process, as well as the influence of the magnetic ionic liquid are assessed. Moreover, the formations that were observed, attributed to bulk nanobubbles, were compared to results of other similar studies and the measured sizes of the observed bubbles from this direct imaging technique were correlated with the results of dynamic light scattering (DLS) and Tyndall effect obtained for the bubbles previously at NCSR “Demokritos”.	en
heal.sponsor	Erasmus+ programme	en
heal.advisorName	Koutsos, Vasileios	en
heal.advisorName	Theodorou, Doros	enen
heal.committeeMemberName	Theodorou, Doros	en
heal.committeeMemberName	Pavlatou, Evangelia	en
heal.committeeMemberName	Kokosis, Antonis	en
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών. Τομέας Επιστήμης και Τεχνικής των Υλικών (ΙΙΙ)	el
heal.academicPublisherID	ntua
heal.numberOfPages	69 σ.	el
heal.fullTextAvailability	false