Mass transfer from freely rising microbubbles in aqueous solutions of surfactant or salt

Shunya Tanaka, Sven Kastens, Satoko Fujioka, Michael Schlüter, Koichi Terasaka

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Microbubbles are used in many applications. One of the major advantages of using microbubbles is to improve the mass transfer of gases to the bulk phase. In this study, mass transfer from single microbubbles that rise in ultrapure water and aqueous solutions of surfactants (SDS, Pluronic F68) or salt (NaCl) was investigated. The rising and dissolution behaviors of single air microbubbles were observed using a high-speed imaging technique by which the rising velocity, UB, and the mass transfer coefficient, kL, were optically evaluated. We found that the rising velocity of microbubbles obeys Stokes’ law, indicating that the surface of the microbubbles used in this study is immobile, despite their rising in ultrapure water. The obtained mass transfer coefficients were in good agreement with those predicted by Ranz and Marshall's correlation for the Sherwood number, Sh. Using the two correlations for UB and Sh, a theoretical model that describes the mass transfer from a microbubble was constructed. The proposed model can predict the dissolution of single microbubbles rising in ultrapure water and aqueous solutions with an accuracy of ±10% in terms of dissolution time.

Original languageEnglish
Article number121246
JournalChemical Engineering Journal
Volume387
DOIs
Publication statusPublished - 2020 May 1

Keywords

  • Mass transfer coefficient
  • Microbubble
  • Rising velocity
  • Sherwood number
  • Surfactant

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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