TY - JOUR
T1 - Application of the Diffused Double Layer Theory to Nanobubbles
AU - Meegoda, Jay N.
AU - Hewage, Shaini Aluthgun
AU - Batagoda, Janitha H.
N1 - Funding Information:
This research was sponsored by the US National Science Foundation Award 1634857 entitled “Remediation of Contaminated Sediments with Ultrasound and Ozone Nano-bubbles”. The program manager at NSF is Dr. Richard Fragaszy. Authors also would like to thank Professor Wen Zhang for the support in the DLS analysis.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/9/17
Y1 - 2019/9/17
N2 - Nanobubbles have electrically charged interfaces; hence, the diffused double layer theory can be applied to explain the behavior of nanobubbles in different electrolytic solutions. In this research, oxygen nanobubbles were generated in NaCl solutions of different concentrations, and bubble size and ζ potentials were measured just after the generation and after 1 week. The measured data and diffused double layer theory were used to compute the surface charge density, the potential due to the surface charge, and the interaction energy between bubbles. With the increased NaCl concentration, bubble size, surface charge density, and the number of negative charges increased, while the magnitude of ζ potential/surface potential, double layer thickness, internal pressure, and the electrostatic repulsion force decreased. The same trend was observed after 1 week. The net total energy calculation for the 0.001 M NaCl solution showed that the bubble repulsion for an intermediate separation distance had a 6.99 × 10-20 J energy barrier, which prevented bubble coalescence. Hence, the 0.001 M NaCl solution produced stable nanobubbles. The calculation of internal pressure inside nanobubbles showed a reduction in the interfacial pressure difference with the increased NaCl concentration. The test results, as well as diffuse double layer and net total energy calculations, showed that the most stable bubbles were obtained with 0.001 M NaCl concentration and the least stability was recorded with the highest amount (0.1 M) of NaCl concentration.
AB - Nanobubbles have electrically charged interfaces; hence, the diffused double layer theory can be applied to explain the behavior of nanobubbles in different electrolytic solutions. In this research, oxygen nanobubbles were generated in NaCl solutions of different concentrations, and bubble size and ζ potentials were measured just after the generation and after 1 week. The measured data and diffused double layer theory were used to compute the surface charge density, the potential due to the surface charge, and the interaction energy between bubbles. With the increased NaCl concentration, bubble size, surface charge density, and the number of negative charges increased, while the magnitude of ζ potential/surface potential, double layer thickness, internal pressure, and the electrostatic repulsion force decreased. The same trend was observed after 1 week. The net total energy calculation for the 0.001 M NaCl solution showed that the bubble repulsion for an intermediate separation distance had a 6.99 × 10-20 J energy barrier, which prevented bubble coalescence. Hence, the 0.001 M NaCl solution produced stable nanobubbles. The calculation of internal pressure inside nanobubbles showed a reduction in the interfacial pressure difference with the increased NaCl concentration. The test results, as well as diffuse double layer and net total energy calculations, showed that the most stable bubbles were obtained with 0.001 M NaCl concentration and the least stability was recorded with the highest amount (0.1 M) of NaCl concentration.
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U2 - 10.1021/acs.langmuir.9b01443
DO - 10.1021/acs.langmuir.9b01443
M3 - Article
C2 - 31433652
AN - SCOPUS:85072350109
SN - 0743-7463
VL - 35
SP - 12100
EP - 12112
JO - Langmuir
JF - Langmuir
IS - 37
ER -