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Fitzgerald E, Kumar A, Poulose S, Coey JMD. Interaction and Stability of Nanobubbles and Prenucleation Calcium Clusters during Ultrasonic Treatment of Hard Water. ACS OMEGA 2024; 9:2547-2558. [PMID: 38250393 PMCID: PMC10795157 DOI: 10.1021/acsomega.3c07305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/27/2023] [Accepted: 12/08/2023] [Indexed: 01/23/2024]
Abstract
To investigate the stability of nanobubbles in natural hard water, a series of eight samples ranging in hardness from 0 to 332 mg/L CaCO3 were sonicated for periods of 5-45 min with an ultrasonic horn. Conductivity, temperature, ζ-potential, composition, and pH of the water were analyzed, together with the crystal structure of any calcium carbonate precipitate. Quasi-stable populations of bulk nanobubbles in Millipore and soft water are characterized by a ζ-potential of -35 to -20 mV, decaying over 60 h or more. After sonicating the hardest waters for about 10 min, they turn cloudy due to precipitation of amorphous calcium carbonate when the water temperature reaches 40 °C; the ζ-potential then jumps from -10 to +20 mV and remains positive for several days. From an analysis of the change of conductivity of the hard water before and after sonication, it is estimated that 37 ± 5% of calcium was not originally in solution but existed in nanoscale prenucleation clusters, which decorate the nanobubbles formed in the early stages of sonication. Heating and charge screening in the nanobubble colloid cause the decorated bubbles to collapse or disperse, leaving an amorphous precursor of aragonite. Sonicating the soft supernatant increases its conductivity and pH and restores the negative ζ-potential associated with bulk nanobubbles, but there is no further precipitation. Our study of the correlation between nanobubble production and calcium agglomeration spanning the hardness and composition ranges of natural waters shows that the sonication method for introducing nanobubbles is viable only for hard water if it is kept cold; the stability of the nanobubble colloid will be reduced in any case by the presence of dissolved calcium and magnesium.
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Affiliation(s)
- Eavan Fitzgerald
- School of Physics, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Anup Kumar
- School of Physics, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Sruthy Poulose
- School of Physics, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - J. M. D. Coey
- School of Physics, Trinity College Dublin, Dublin D02 PN40, Ireland
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2
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Fundamentals and applications of nanobubbles: A review. Chem Eng Res Des 2022. [DOI: 10.1016/j.cherd.2022.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Horseman T, Lin S. Exceptional Mineral Scaling Resistance from the Surface Gas Layer: Impacts of Surface Wetting Properties and the Gas Layer Charging Mechanism. ACS ENVIRONMENTAL AU 2022; 2:418-427. [PMID: 37101459 PMCID: PMC10125293 DOI: 10.1021/acsenvironau.2c00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Mineral scaling is a phenomenon that occurs on submerged surfaces in contact with saline solutions. In membrane desalination, heat exchangers, and marine structures, mineral scaling reduces process efficiency and eventually leads to process failure. Therefore, achieving long-term scaling resistance is beneficial to enhancing process performance and reducing operating and maintenance costs. While evidence shows that superhydrophobic surfaces may reduce mineral scaling kinetics, prolonged scaling resistance is limited due to the finite stability of the entrained gas layer present in a Cassie-Baxter wetting state. Additionally, superhydrophobic surfaces are not always feasible for all applications, but strategies for long-term scaling resistance with smooth or even hydrophilic surfaces are often overlooked. In this study, we elucidate the role of interfacial nanobubbles on the scaling kinetics of submerged surfaces of varied wetting properties, including those that do not entrain a gas layer. We show that both solution conditions and surface wetting properties that promote interfacial bubble formation enhances scaling resistance. In the absence of interfacial bubbles, scaling kinetics decrease as surface energy decreases, while the presence of bulk nanobubbles enhances the scaling resistance of the surface with any wetting property. The findings in this study allude to scaling mitigation strategies that are enabled by solution and surface properties that promote the formation and stability of interfacial gas layers and provide insights to surface and process design for greater scaling resistance.
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Affiliation(s)
- Thomas Horseman
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Shihong Lin
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Civil and Environmental Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- . Phone: +1 (615) 322-7226
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Reduction of calcified plaque volume in ex vivo pericardial tissue, with nanobubbles. Colloids Surf B Biointerfaces 2022; 217:112666. [DOI: 10.1016/j.colsurfb.2022.112666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 06/22/2022] [Accepted: 06/25/2022] [Indexed: 11/16/2022]
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Agarwal K, Trivedi M, Nirmalkar N. Does salting-out effect nucleate nanobubbles in water: Spontaneous nucleation? ULTRASONICS SONOCHEMISTRY 2022; 82:105860. [PMID: 34915251 PMCID: PMC8683758 DOI: 10.1016/j.ultsonch.2021.105860] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/30/2021] [Accepted: 12/04/2021] [Indexed: 05/05/2023]
Abstract
The solubility of gases in aqueous salt solution decreases with the salt concentration, often termed the "salting-out effect." The dissolution of salt in water is followed by dissociation of salt and further solvation of ions with water molecules. The solvation weakens the affinity of gaseous molecules, and thus it releases the excess dissolved gas. Now it is interesting to know that what happens to the excess gas released during salting-out? Since it is imperative to note that the transfer of the dissolved gas in the bulk liquid may often occur in the form of nanobubbles. In this work, we have answered this question by investigating the nano-entities nucleation during the salting-out effect. The solubility of gases in aqueous salt solution decreases with the salt concentration, and it is often termed as the "salting-out effects." The dissolution of salt in water undergoes dissociation of salt and further solvation of ions with water molecules. The solvation weakens the affinity of gaseous molecules, and thus it releases the excess dissolved gas. Now it is interesting to know that what happens to the excess gas released during salting-out? While it is also imperative to note that the gas transfer in the bulk liquid often occurs in the form of bubbles. With this hypothesis, we have experimentally investigated that whether the salting-out effect nucleates nanobubble or not. What is the strong scientific evidence to prove that they are nanobubbles? Does the salting-out parameter affect the number density? The answers to such questions are essential for the fundamental understanding of the origin and driving force for nanobubble generation. We have provided three distinct proofs for the nano-entities to be the nanobubbles, namely, (1) by freezing and thawing experiments, (2) by destroying the nanobubbles under ultrasound field, and (3) we also proposed a novel method for refractive index estimation of nanobubbles to differentiate them from nano drops and nanoparticles. The refractive index (RI) of nanobubbles was estimated to be 1.012 for mono- and di-valent salts and 1.305 for trivalent salt. The value of RI closer to 1 provides strong evidence of gas-filled nanobubbles. Both positive and negative charged nanobubbles nucleate during the salting-out effect depending upon the valency of salt. The nanobubbles during the salting-out effect are stable only for up to three days. This shorter stability could plausibly be due to reduced colloidal stability at a low surface charge.
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Affiliation(s)
- Kalyani Agarwal
- Department of Chemical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Mohit Trivedi
- Department of Chemical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Neelkanth Nirmalkar
- Department of Chemical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India.
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Zhou L, Wang S, Zhang L, Hu J. Generation and stability of bulk nanobubbles: A review and perspective. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101439] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Ji Y, Guo Z, Tan T, Wang Y, Zhang L, Hu J, Zhang Y. Generating Bulk Nanobubbles in Alcohol Systems. ACS OMEGA 2021; 6:2873-2881. [PMID: 33553905 PMCID: PMC7860054 DOI: 10.1021/acsomega.0c05222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Bulk nanobubbles (NBs) have attracted wide attention due to their peculiar physicochemical properties and great potential in applications in various fields. However, so far there are no reports on bulk NBs generated in pure organic systems, which we think is very important as NBs would largely improve the efficiency of gas-liquid mass transfer and facilitate chemical reactions to take place. In this paper, we verified that air and N2 NBs could be generated in a series of alcohol solutions by using various methods including acoustical cavitation, pressurization-depressurization, and vibration. The experiments proved that NBs existed in alcohol solutions, with a highest density of 5.8 × 107 bubble/mL in propanol. Our results also indicated that bulk NBs could stably exist for at least hours in alcohol systems. The parameters in generating NBs in alcohols were optimized. Our findings open up an opportunity for improving gas-liquid mass transfer efficiency in the field of the chemical industry.
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Affiliation(s)
- Yuwen Ji
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Guo
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Tingyuan Tan
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Yujiao Wang
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Lijuan Zhang
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Zhangjiang
Lab, Shanghai Advanced Research Institute,
Chinese Academy of Sciences, Shanghai 201210, China
| | - Jun Hu
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Zhangjiang
Lab, Shanghai Advanced Research Institute,
Chinese Academy of Sciences, Shanghai 201210, China
| | - Yi Zhang
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- Zhangjiang
Lab, Shanghai Advanced Research Institute,
Chinese Academy of Sciences, Shanghai 201210, China
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