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Generation of micro- and nano-bubbles in water by dissociation of gas hydrates

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Title: Generation of micro- and nano-bubbles in water by dissociation of gas hydrates
Authors: Uchida, Tsutomu Browse this author →KAKEN DB
Yamazaki, Kenji Browse this author
Gohara, Kazutoshi Browse this author →KAKEN DB
Keywords: Microbubble
Nanobubble
Gas Hydrate Dissociation
Freeze Fracture Replica
Bubble Pressure
Memory Effect
Issue Date: May-2016
Publisher: Springer
Journal Title: Korean Journal of Chemical Engineering
Volume: 33
Issue: 5
Start Page: 1749
End Page: 1755
Publisher DOI: 10.1007/s11814-016-0032-7
Abstract: Gas hydrate crystals have a structure in which one molecule is enclathrated in a cage of water molecules. When such a crystal dissociates in water, each enclathrated molecule, generally vapor at standard temperature and pressure, directly dissolves into the water. After the solution is supersaturated, excess gas molecules from further dissociation start forming small bubbles called micro- and nano-bubbles (MNBs). However, it is difficult to identify such small bubbles dispersed in liquid because they are smaller than a microscope's optical resolution. To confirm the formation of MNBs after gas hydrate dissociation, we used a transmission electron microscope (TEM) to analyze freeze-fracture replicas of CH4-hydrate dissociation solution. The TEM images indicate the existence of MNBs in the solution, with a number concentration similar to that from a commercially supplied generator. Raman spectroscopic measurements on the CH4-hydrate dissociated solution were then used to confirm that the MNBs contain CH4 vapor, and to estimate experimentally the inner pressure of the CH4 MNBs. These results suggest that the dissociation of gas hydrate crystals in water is a simple, effective method to obtain MNB solution. We then discuss how such MNBs may play a key role in the memory effect of gas-hydrate recrystallization.
Rights: The final publication is available at Springer via http://dx.doi.org/10.1007/s11814-016-0032-7.
Type: article (author version)
URI: http://hdl.handle.net/2115/65570
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 内田 努

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