TY - JOUR
T1 - Molecular dynamics simulation of bulk nanobubbles
AU - Aluthgun Hewage, Shaini
AU - Meegoda, Jay N.
N1 - Funding Information:
This research was sponsored by the National Science Foundation, United States, Award #1634857 (Remediation of Contaminated Sediments with Ultrasound and Ozone Nanobubbles). The program managers at NSF were Drs. Richard Fragaszy and Giovanna Biscontin. The authors would also like to acknowledge XSEDE, United States, supercomputing seed allocation Awards # TG-DMR180060 (Computational Modeling of Nano Bubbles), #TG-ASC200044 (Molecular Dynamic Simulation of Mineralization of PFAS Using Ultrasound), and regular allocation Award # DMR20019 (Molecular Dynamic Simulation of Bulk Nano Bubbles), and Frontera, TACC, United States, Award #EAR21005 (Molecular Dynamic Simulation of Bulk Nanobubbles). The constructive review of the manuscript by anonymous reviewers substantially enhanced our presentation. Finally, the authors would also like to thank Dr. Dibakar Datta and doctoral student Jatin Kashyap at NJIT, who guided the authors in performing Molecular Dynamic Simulations and introduced the XSEDE supercomputing.
Funding Information:
This research was sponsored by the National Science Foundation , United States, Award #1634857 (Remediation of Contaminated Sediments with Ultrasound and Ozone Nanobubbles). The program managers at NSF were Drs. Richard Fragaszy and Giovanna Biscontin. The authors would also like to acknowledge XSEDE , United States, supercomputing seed allocation Awards # TG-DMR180060 (Computational Modeling of Nano Bubbles) , #TG-ASC200044 (Molecular Dynamic Simulation of Mineralization of PFAS Using Ultrasound), and regular allocation Award # DMR20019 (Molecular Dynamic Simulation of Bulk Nano Bubbles), and Frontera, TACC , United States, Award #EAR21005 (Molecular Dynamic Simulation of Bulk Nanobubbles). The constructive review of the manuscript by anonymous reviewers substantially enhanced our presentation. Finally, the authors would also like to thank Dr. Dibakar Datta and doctoral student Jatin Kashyap at NJIT, who guided the authors in performing Molecular Dynamic Simulations and introduced the XSEDE supercomputing.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/10/5
Y1 - 2022/10/5
N2 - The long-term stability of nanobubbles with high internal gas pressure is a puzzling question for nanobubble researchers. The classical Molecular Dynamics simulation based on LAMMPS software was used to evaluate the performance of an oxygen nanobubble with high gas density. This research consists of two main cases. In the first case, bubble behavior was examined with 3247 O2 molecules embedded in a 4.5 nm radius spherical volume to represent the bubble and was surrounded by 438,490 H2O molecules with 1 g/cm3 density. In the second case, the parametric study was conducted while maintaining the same parameters where the amount of O2 molecules changed at the initial configuration. Hence six different O2 bubble configurations were simulated under two different temperature settings, 20 ℃ and 30 ℃. The Lennard Jones potentials are used for molecular interactions. The simulations were run first under the NVT and then changed to the NPT ensemble. Simulation results were analyzed for bubble size, pressure, surface tension, gas diffusion, the influence of internal initial gas densities, gas concentration, and temperature conditions. The high initial gas concentration with high initial internal gas density causes a more stable bubble condition under both NVT and NPT ensembles. This stability can be attributed to the gas supersaturation conditions. The systems with low initial internal gas densities transferred to a smaller radius gas cluster with a high internal density as they shifted to the NPT ensemble. The system with a higher temperature causes elevated system pressures at NVT and volume expansion during NPT. Under NVT simulation, bubble size was higher at lower temperatures. Under NPT conditions, bubble size increases for larger initial density cases and decreases for lower density cases. Further increased temperature causes faster gas diffusion, and higher internal bubble pressure leads to unstable conditions.
AB - The long-term stability of nanobubbles with high internal gas pressure is a puzzling question for nanobubble researchers. The classical Molecular Dynamics simulation based on LAMMPS software was used to evaluate the performance of an oxygen nanobubble with high gas density. This research consists of two main cases. In the first case, bubble behavior was examined with 3247 O2 molecules embedded in a 4.5 nm radius spherical volume to represent the bubble and was surrounded by 438,490 H2O molecules with 1 g/cm3 density. In the second case, the parametric study was conducted while maintaining the same parameters where the amount of O2 molecules changed at the initial configuration. Hence six different O2 bubble configurations were simulated under two different temperature settings, 20 ℃ and 30 ℃. The Lennard Jones potentials are used for molecular interactions. The simulations were run first under the NVT and then changed to the NPT ensemble. Simulation results were analyzed for bubble size, pressure, surface tension, gas diffusion, the influence of internal initial gas densities, gas concentration, and temperature conditions. The high initial gas concentration with high initial internal gas density causes a more stable bubble condition under both NVT and NPT ensembles. This stability can be attributed to the gas supersaturation conditions. The systems with low initial internal gas densities transferred to a smaller radius gas cluster with a high internal density as they shifted to the NPT ensemble. The system with a higher temperature causes elevated system pressures at NVT and volume expansion during NPT. Under NVT simulation, bubble size was higher at lower temperatures. Under NPT conditions, bubble size increases for larger initial density cases and decreases for lower density cases. Further increased temperature causes faster gas diffusion, and higher internal bubble pressure leads to unstable conditions.
KW - Bulk nanobubble
KW - Diffusion
KW - Stability
KW - Supersaturation
KW - Surface tension
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U2 - 10.1016/j.colsurfa.2022.129565
DO - 10.1016/j.colsurfa.2022.129565
M3 - Article
AN - SCOPUS:85140594391
SN - 0927-7757
VL - 650
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
M1 - 129565
ER -