1
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Wang C, Lu Y. Surface Morphology Enriching the Energy Barrier Leads to the Adsorption Characteristic of Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11628-11645. [PMID: 37566553 DOI: 10.1021/acs.langmuir.3c01170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
With the emergence of nanobubble research, nanobubble distribution morphology at the interface and its stability control become the bottlenecks of nanobubble resistance reduction applications. In this paper, the evolutionary behavior of nanobubbles on smooth and step HOPG surfaces was compared through molecular dynamics studies. The results show that the surface energy barrier provided by the step HOPG surface restricts diffusion of gas molecules. Then, a method of multisolvent evaporation for preparing hydrophobic nanoindent surfaces was proposed, which can achieve phase separation through different evaporation rates of multisolvents, thus realizing the preparation of surface structures with uniform distribution of nanoindents. In this paper, the nucleation processes of nanobubbles on PS nanoindent hydrophobic surface, HOPG flat hydrophobic surface, and HOPG nanostep hydrophobic surface were compared by using atomic force microscopy in liquid experiment. The evolution of the volume and distribution morphology of nanobubbles on the three nanostructures was observed by 24 h in situ tests, revealing that the energy barrier effect arising from the uneven surface structure can effectively prevent adjacent nanobubbles from merging in close proximity to each other. It is also pointed out that the hydrophobic nanoindents prepared by using the multivariate solvent evaporation method in this paper can cover most of nanobubbles for stable adsorption. It can be seen from the results that the volume drop of the nanobubbles on the HOPG flat hydrophobic surface is 27% and that on the HOPG nanostep and the PS nanoindent hydrophobic surface it is reduced to 19% and 3% under the effect of structural energy barriers, respectively. The density of the nanostructures determines whether the existence of nanobubbles is stable. The coverage of nanobubbles on the HOPG flat hydrophobic surface was 3.313% when the existence of nanobubbles was mostly stable. The HOPG nanostep and PS nanoindent sizes were positively correlated with the morphological size of the nanobubbles, which increased the coverage of the nanobubbles on the hydrophobic surface of the HOPG nanostep and PS nanoindent to 5.229% and 4.437%, respectively, when the existence of nanobubbles was mostly stable.
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Affiliation(s)
- Chao Wang
- Key Laboratory of Metallurgical Equipment and Control Technology Wuhan University of Science and Technology, Wuhan 430081, China
- Key Laboratory of Mechanical Transmission and Manufacturing Engineering Wuhan University of Science and Technology, Wuhan 430081, China
| | - Yan Lu
- Key Laboratory of Metallurgical Equipment and Control Technology Wuhan University of Science and Technology, Wuhan 430081, China
- Precision Manufacturing Research Institute Wuhan University of Science and Technology, Wuhan 430081, China
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2
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Perumanath S, Pillai R, Borg MK. Contaminant Removal from Nature's Self-Cleaning Surfaces. NANO LETTERS 2023; 23:4234-4241. [PMID: 37154913 DOI: 10.1021/acs.nanolett.3c00257] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Many organisms in nature have evolved superhydrophobic surfaces that leverage water droplets to clean themselves. While this ubiquitous self-cleaning process has substantial industrial promise, experiments have so far been unable to comprehend the underlying physics. With the aid of molecular simulations, here we rationalize and theoretically explain self-cleaning mechanisms by resolving the complex interplay between particle-droplet and particle-surface interactions, which originate at the nanoscale. We present a universal phase diagram that consolidates (a) observations from previous surface self-cleaning experiments conducted at micro-to-millimeter length scales and (b) our nanoscale particle-droplet simulations. Counterintuitively, our analysis shows that an upper limit for the radius of the droplet exists to remove contaminants of a particular size. We are now able to predict when and how particles of varying scale (from nano-to-micrometer) and adhesive strengths are removed from superhydrophobic surfaces.
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Affiliation(s)
| | - Rohit Pillai
- School of Engineering, University of Edinburgh, Edinburgh EH9 3FB, U.K
| | - Matthew K Borg
- School of Engineering, University of Edinburgh, Edinburgh EH9 3FB, U.K
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3
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Morishita R, Shimada M, Nagao M, Shimizu S, Kamei N, Takeda-Morishita M. In Vivo Proof of Biological Safety and Physiological Effects of Orally Ingested Water Containing H 2-Filled Ultrafine Bubbles (UFBs). Biol Pharm Bull 2023; 46:343-347. [PMID: 36724963 DOI: 10.1248/bpb.b22-00631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Owing to their unique physicochemical properties and diverse biological effects, ultrafine bubbles (UFBs) have recently been expected to be utilized for industrial and biological purposes. Thus, this study investigated the biological safety of UFBs in water for living beings in drinking the water with a view to future use in health sciences. In this study, we used H2-filled UFBs (NanoGAS®) that can hold hydrogen in the aqueous phase for a long time. Mice were randomly assigned to one of three groups: those receiving NanoGAS® water, reverse osmosis water, or natural mineral water, and they ingested it ad libitum for one month or three months. As a result, subchronic drinking of NanoGAS® water does not affect either the common blood biochemical parameters or the health of the organs and mucosal membranes. Our results, for the first time, scientifically demonstrated the biological safety of H2-filled UFBs water for subchronic oral consumption.
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Affiliation(s)
- Risako Morishita
- Shinbiosis Corp., 106 Kobe Health Industry Development Center.,Intestinal Microbiota Transplantation Clinical Research Inc
| | - Miki Shimada
- Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University
| | - Minami Nagao
- Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University
| | - Shin Shimizu
- Shinbiosis Corp., 106 Kobe Health Industry Development Center.,Intestinal Microbiota Transplantation Clinical Research Inc
| | - Noriyasu Kamei
- Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University
| | - Mariko Takeda-Morishita
- Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University
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4
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Fang H, Geng Z, Guan N, Zhou L, Zhang L, Hu J. Controllable generation of interfacial gas structures on the graphite surface by substrate hydrophobicity and gas oversaturation in water. SOFT MATTER 2022; 18:8251-8261. [PMID: 36278324 DOI: 10.1039/d2sm00849a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Spherical nanobubbles and flat micropancakes are two typical states of gas aggregation on solid-liquid surfaces. Micropancakes, which are quasi-two-dimensional gaseous structures, are often produced accompanied by surface nanobubbles. Compared with surface nanobubbles, the intrinsic properties of micropancakes are barely understood due to the challenge of the highly efficient preparation and characterization of such structures. The hydrophobicity of the substrate and gas saturation of solvents are two crucial factors for the nucleation and stability of interfacial gas domains. Herein, we investigated the synergistic effect of the surface hydrophobicity and gas saturation on the generation of interfacial gas structures. Different surface hydrophobicities were achieved by the aging process of highly oriented pyrolytic graphite (HOPG). The results indicated that higher surface hydrophobicity and gas oversaturation could create surface nanobubbles and micropancakes with higher efficiency. Strong surface hydrophobicity could promote nanobubble nucleation and higher gas saturation would induce bigger nanobubbles. Degassed experiments could remove most of these structures and prove that they are actually gaseous domains. Finally, we draw a region diagram to describe the formation conditions of nanobubbles, micropancakes based on observations. These results would be very helpful for further understanding the formation of interfacial gas structures on the hydrophobic surface under different gas saturation.
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Affiliation(s)
- Hengxin Fang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhanli Geng
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nan Guan
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Limin Zhou
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Lijuan Zhang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Jun Hu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
- The Interdisciplinary Research Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
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5
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Inami W, Hara N, Kawata Y, Kobayashi H, Fujita T. High resolution imaging of ultrafine bubbles in water by Atmospheric SEM-CL. Micron 2022; 162:103351. [PMID: 36174306 DOI: 10.1016/j.micron.2022.103351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/31/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
Various analytical methods such as high-resolution observation of ultrafine bubbles in water are required to clarify the mechanisms and interrelationships of various effects brought about by ultrafine bubbles. In this study, we used atmospheric scanning electron microscopy-cathodoluminescence (ASEM-CL) method for observing ultrafine bubbles in water. ASEM can observe samples in water, and the fine electron beam provides high spatial resolution. Furthermore, the gas in the bubble can be estimated from the CL emission spectrum. We have measured characteristics such as bubble size and particle number density. Also, the CL spectra has shown that the ultrafine bubbles contained nitrogen.
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Affiliation(s)
- Wataru Inami
- Shizuoka University, Graduate School of Science and Technology, Hamamatsu 4328561, Japan; Shizuoka University, Research Institute of Electronics, Hamamatsu 4328011, Japan.
| | - Naoto Hara
- Shizuoka University, Graduate School of Science and Technology, Hamamatsu 4328561, Japan
| | - Yoshimasa Kawata
- Shizuoka University, Graduate School of Science and Technology, Hamamatsu 4328561, Japan; Shizuoka University, Research Institute of Electronics, Hamamatsu 4328011, Japan
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6
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Hu K, Luo L, Sun X, Li H. Unraveling the effects of gas species and surface wettability on the morphology of interfacial nanobubbles. NANOSCALE ADVANCES 2022; 4:2893-2901. [PMID: 36132003 PMCID: PMC9418701 DOI: 10.1039/d2na00009a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
The morphology of interfacial nanobubbles (INBs) is a crucial but controversial topic in nanobubble research. We carried out atomistic molecular dynamics (MD) simulations to comprehensively study the morphology of INBs controlled by several determinant factors, including gas species, surface wettability, and bubble size. The simulations show that H2, O2 and N2 can all form stable INBs, with the contact angles (CAs, on the liquid side) following the order CA(H2) < CA(N2) < CA(O2), while CO2 prefers to form a gas film (pancake) structure on the substrate. The CA of INBs demonstrates a linear relation with the strength of interfacial interaction; however, a limited bubble CA of ∼25° is found on superhydrophilic surfaces. The high gas density and high internal pressure of the INBs are further confirmed, accompanied by strong interfacial gas enrichment (IGE) behavior. The morphology study of differently sized INBs shows that the internal density of the gas is drastically decreased with the bubble size at the initial stage of bubble nucleation, while the CA remains almost constant. Based on the simulation results, a modified Young's equation is presented for describing the extraordinary morphology of INBs.
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Affiliation(s)
- Kadi Hu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
| | - Liang Luo
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology Beijing 100029 PR China
| | - Xiaoming Sun
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology Beijing 100029 PR China
| | - Hui Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemistry Technology Beijing 100029 PR China
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7
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Babu KS, Amamcharla JK. Generation methods, stability, detection techniques, and applications of bulk nanobubbles in agro-food industries: a review and future perspective. Crit Rev Food Sci Nutr 2022; 63:9262-9281. [PMID: 35467989 DOI: 10.1080/10408398.2022.2067119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nanobubble (NB) technologies have received considerable attention for various applications due to their low cost, eco-friendliness, scale-up potential, process control, and unique physical characteristics. NB stands for nanoscopic gaseous cavities, typically <1 μm in diameter. NBs can exist on surfaces (surface or interfacial NBs) and be dispersed in a bulk liquid phase (bulk NBs). Compared to the microbubbles, NBs exhibit high specific surface area, negative surface charge, and better adsorption. Bulk NBs can be generated by hydrodynamic/acoustic cavitation, electrolysis, water-solvent mixing, nano-membrane filtration, and so on. NBs exhibit extraordinary longevity compared to microbubbles, prompting the interest of the scientific community aiming for potential applications including medicine, agriculture, food, wastewater treatment, surface cleaning, and so on. Based on the limited amount of research work available regarding the influence of NBs on food matrices, further research, however, needs to be done to provide more insights into its applications in food industries. This review provides an overview of the generation methods for NBs, techniques to evaluate them, and a discussion of their stability and several applications in various fields of science were discussed. However, recent studies have revealed that, despite the many benefits of NB technologies, several NB generating approaches are still limited in their application in specific agro-food industries. Further study should focus on process optimization, integrating various NB generation techniques/combining with other emerging technologies in order to achieve rapid technical progress and industrialization of NB-based technologies.HighlightsNanobubbles (NBs) are stable spherical entities of gas within liquid and are operationally defined as having diameters less than 1 µm.Currently, various reported theories still lack the ability to explain the evidence and stability of NBs in water, numerous NB applications have emerged due to the unique properties of NBs.NB technologies can be applied to various food and dairy products (e.g. yogurt and ice cream) and other potential applications, including agriculture (e.g. seed germination and plant growth), wastewater treatment, surface cleaning, and so on.
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Affiliation(s)
- Karthik S Babu
- Department of Animal Sciences and Industry/Food Science Institute, Kansas State University, Manhattan, Kansas, USA
| | - Jayendra K Amamcharla
- Department of Animal Sciences and Industry/Food Science Institute, Kansas State University, Manhattan, Kansas, USA
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8
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Li P, Wang J, Liao Z, Ueda Y, Yoshikawa K, Zhang G. Microbubbles for Effective Cleaning of Metal Surfaces Without Chemical Agents. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:769-776. [PMID: 34985892 DOI: 10.1021/acs.langmuir.1c02769] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Traditional cleaning methods involving surfactants and ultrasound generate large amounts of wastewater. Microbubbles offer a more eco-friendly technology for interface cleaning. Here, we explored the efficiency of microbubbles for cleaning oil from metal surfaces. Air microbubbles at concentrations as high as 106 particles/mL were generated by hydrodynamic cavitation. Under optimal conditions, cleaning efficiencies for the removal of oil from carbon-steel and stainless-steel surfaces were 78.5 and 49.8% after 15 min, respectively, compared to only 6.5 and 9.9% without microbubbles. Additionally, combining microbubble treatment with the ultrasonic method achieved a higher efficiency than ultrasonic cleaning alone, achieving an efficiency of 85.5% after 3 min compared to 69.0%. The mechanism of microbubble cleaning was determined using a fluorescence observation system, and a model was established to describe the cleaning process. The use of microbubbles produced less emulsified oil wastewater because the oil that attaches to the microbubble surface floats with the bubbles to the surface of the cleaning water, where it can be removed, allowing for water recycling. This novel microbubble cleaning technology, which both enhances cleaning efficiency and reduces wastewater production, represents a viable and eco-friendly option for degreasing processes.
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Affiliation(s)
- Pan Li
- School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China
- School of Environmental Science and Engineering, State Key Laboratory of Control and Resource Reuse, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - JiaHao Wang
- School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China
| | - ZhengHao Liao
- School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China
| | - Yoshikatsu Ueda
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 6110011, Japan
| | - Kiyoshi Yoshikawa
- Institute of Advanced Energy, Kyoto University, Sakyo, Kyoto 6068501, Japan
| | - GuoXing Zhang
- Gubei International Fortune Center, Shanghai Challenge Textile Co., Ltd., RM303, 1438 Hongqiao Road, Changning District, Shanghai 201504, P. R. China
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9
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Lu Y, Yang L, Kuang Y, Song Y, Zhao J, Sum AK. Molecular simulations on the stability and dynamics of bulk nanobubbles in aqueous environments. Phys Chem Chem Phys 2021; 23:27533-27542. [PMID: 34874384 DOI: 10.1039/d1cp03325e] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nanobubbles have attracted significant attention due to their unexpectedly long lifetimes and stabilities in liquid solutions. However, explanations for the unique properties of nanobubbles at the molecular scale are somewhat controversial. Of special interest is the validity of the Young-Laplace equation in predicting the inner pressure of such bubbles. In this work, large-scale molecular dynamics simulations were performed to study the stability and diffusion of nanobubbles of methane in water. Two types of force field, atomistic and coarse-grained, were used to compare the calculated results. In accordance with predictions from the Young-Laplace equation, it was found that the inner pressure of the nanobubbles increased with decreasing nanobubble size. Consequently, a large pressure difference between the nanobubble and its surroundings resulted in the high solubility of methane molecules in water. The solubility was considered to enable nanobubble stability at exceptionally high pressures. Smaller bubbles were observed to be more mobile via Brownian motion. The calculated diffusion coefficient also showed a strong dependence on the nanobubble size. However, this active mobility of small nanobubbles also triggered a mutable nanobubble shape over time. Nanobubbles were also found to coalesce when they were sufficiently close. A critical distance between two nanobubbles was thus identified to avoid coalescence. These results provide insight into the behavior of nanobubbles in solution and the mechanism of their unique stability while withstanding high inner pressures.
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Affiliation(s)
- Yi Lu
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
| | - Lei Yang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
| | - Yangmin Kuang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
| | - Yongchen Song
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
| | - Jiafei Zhao
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
| | - Amadeu K Sum
- Phases to Flow Laboratory, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA.
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10
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Peng Z, Zhang B. Nanobubble Labeling and Imaging with a Solvatochromic Fluorophore Nile Red. Anal Chem 2021; 93:15315-15322. [PMID: 34751561 DOI: 10.1021/acs.analchem.1c02685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein, we report the use of a polarity-sensitive, solvatochromic fluorophore Nile red to label and probe individual hydrogen nanobubbles on the surface of an indium-tin oxide (ITO) electrode. Nanobubbles are generated from the reduction of water on ITO and fluorescently imaged from the transient adsorption and desorption process of single Nile red molecules at the nanobubble surface. The ability to label and fluorescently image individual nanobubbles with Nile red suggests that the gas/solution interface is hydrophobic in nature. Compared to the short labeling events using rhodamine fluorophores, Nile red-labeled events appear to be longer in duration, suggesting that Nile red has a higher affinity to the bubble surface. The stronger fluorophore-bubble interaction also leads to certain nanobubbles being co-labeled by multiple Nile red molecules, resulting in the observation of super-bright and long-lasting labeling events. Based on these interesting observations, we hypothesize that Nile red molecules may start clustering and form some kind of molecular aggregates when they are co-adsorbed on the same nanobubble surface. The ability to observe super-bright and long-lasting multifluorophore labeling events also allows us to verify the high stability and long lifetime of electrochemically generated surface nanobubbles.
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Affiliation(s)
- Zhuoyu Peng
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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11
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Yamaguchi M, Ma T, Tadaki D, Hirano-Iwata A, Watanabe Y, Kanetaka H, Fujimori H, Takemoto E, Niwano M. Bactericidal Activity of Bulk Nanobubbles through Active Oxygen Species Generation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9883-9891. [PMID: 34339599 DOI: 10.1021/acs.langmuir.1c01578] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigated the bactericidal activity of bulk nanobubbles (NBs) using E. coli, a model bacterium. Bulk NBs were produced by forcing gas through a porous alumina membrane with an ordered arrangement of nanoscale straight holes in contact with water. NBs with different gas contents, including CO2, O2, and N2, were generated and evaluated for their bactericidal effects. The survival rate of E. coli was significantly reduced in a suspension of CO2-containing NB (CO2-NB water). The N2-NB water demonstrated a small amount of bactericidal behavior, but its impact was not as significant as that of CO2-NB water. When E. coli was retained in O2-NB water, the survival rate was even higher than that in pure water (PW). We investigated the generation of reactive oxygen species (ROS) in NB suspensions by electron spin resonance spectroscopy. The main ROS generated in the NB water were hydroxyl radicals and OH·, and the production of ROS was the strongest in CO2-NB water, which was consistent with the results of the bactericidal effect measurements. We assumed that NB mediated by ROS would exhibit bactericidal behavior and proposed a kinetic model to explain the retention time variation of the survival rate. The results calculated based on the proposed model matched closely with the experimental results.
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Affiliation(s)
| | - Teng Ma
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Daisuke Tadaki
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Ayumi Hirano-Iwata
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | | | - Hiroyasu Kanetaka
- Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan
| | - Hiroshi Fujimori
- Planning & Development Department, Takemoto Yohki Co., Ltd., Tokyo 111-0036, Japan
| | - Emiko Takemoto
- Planning & Development Department, Takemoto Yohki Co., Ltd., Tokyo 111-0036, Japan
| | - Michio Niwano
- Tohoku Fukushi University, Sendai 989-3201, Japan
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
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12
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Lu H, Huang F, Guo H. Differential Removal of Nanoparticles on the Surface of a Thin Film Substrate. ACS OMEGA 2021; 6:16280-16287. [PMID: 34235298 PMCID: PMC8246473 DOI: 10.1021/acsomega.1c00334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/11/2021] [Indexed: 06/13/2023]
Abstract
Purposeful identification, selection, and collection of particles are of great significance in environmental research. Microscopy is the common technique used in previous studies of particle identification. However, the microscopic technique was intricate and time-consuming. To conduct an intensive analysis of targeted particles, there is a need for the development of a simple method that can differentially abandon the nontargeted particles and only retain the targeted particles on the surface of a substrate. In the study, three methods were attempted for differential removal of nontargeted nanoparticles on the surface, including air jet, nanobubble, and ultrasonic methods. Acidic particles were taken as the targeted particles, while nonacidic particles were regarded as nontargeted particles. The results showed that regardless of methods, acidic particles were retained on the surface due to the strong particle-surface interaction. As for nonacidic particles, air jet treatment and nanobubble treatment were not able to completely remove nonacidic particles from the surface with the removal efficiencies of 5.1 ± 3.4 and 89.3 ± 4.1%, respectively, while the nonacidic particles were entirely removed in the ultrasonic treatment. Ethanol rather than deionized (DI) water was the proper solution in the ultrasonic treatment to avoid contamination. In conclusion, ultrasonic by ethanol was fully efficient for differential removal of nonacidic particles on the surface. The principle of differential removal of particles is the differences in the particle-surface interaction force between nonacidic particles (i.e., physically attached particles) and acidic particles (i.e., chemically formed particles). Nonacidic particles are removed from the surface through cavitation to form bubbles in the gap between a nonacidic particle and the surface in the ultrasonic treatment. In contrast, the space between an acidic particle and the surface is filled by the reaction, and thus bubbles cannot enter the crevice to remove the acidic particle. The developed method is useful for aerosol research.
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13
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Nag S, Tomo Y, Takahashi K, Kohno M. Mechanistic Insights into Nanobubble Merging Studied Using In Situ Liquid-Phase Electron Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:874-881. [PMID: 33400870 DOI: 10.1021/acs.langmuir.0c03208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nanobubbles have attracted great interest in recent times because of their application in water treatment, surface cleaning, and targeted drug delivery, yet the challenge remains to gain thorough understanding of their unique behavior and dynamics for their utilization in numerous potential applications. In this work, we have used a liquid-phase electron microscopy technique to gain insights into the quasistatic merging of surface nanobubbles. The electron beam environment was controlled in order to suppress any new nucleation and slow down the merging process. The transmission electron microscopy study reveals that merging of closely positioned surface nanobubbles is initiated by gradual localized changes in the physical properties of the region between the adjoining nanobubble boundary. The observed phenomenon is then analyzed and discussed based on the different perceptions: localized liquid density gradient and bridge formation for gas exchange. In this study, it is estimated that the merging of the stable nanobubbles is initiated by the formation of a thin gas layer. This work not only enhances our understanding of the merging process of stable surface nanobubbles but will also lead to exploration of new domains for nanobubble applications.
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Affiliation(s)
- Sarthak Nag
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
| | - Yoko Tomo
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Koji Takahashi
- Department of Aeronautics and Astronautics, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
| | - Masamichi Kohno
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
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14
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Jadhav AJ, Barigou M. Proving and interpreting the spontaneous formation of bulk nanobubbles in aqueous organic solvent solutions: effects of solvent type and content. SOFT MATTER 2020; 16:4502-4511. [PMID: 32342965 DOI: 10.1039/d0sm00111b] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We show that the mixing of organic solvents with pure water leads to the spontaneous formation of suspended nano-entities which exhibit long-term stability on the scale of months. A wide range of solvents representing different functional groups are studied: methanol, ethanol, propanol, acetone, DMSO and formamide. We use various physical and chemical analytical techniques to provide compounded evidence that the nano-entities observed in all these aqueous solvent solutions must be gas-filled nanobubbles as they cannot be attributed to solvent nanodroplets, impurities or contamination. The nanobubble suspensions are characterized in terms of their bubble size distribution, bubble number density and zeta potential. The bubble number density achieved is a function of the type of solvent. It increases sharply with solvent content, reaching a maximum at an intermediate solvent concentration, before falling off to zero. We show that, whilst bulk nanobubbles can exist in pure water, they cannot exist in pure organic solvents and they disappear at some organic solvent-water ratio depending on the type of solvent. The gas solubility of the solvent relative to water as well as the molecular structure of the solvent are determining factors in the formation and stability of bulk nanobubbles. These phenomena are discussed and interpreted in the light of the experimental results obtained.
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Affiliation(s)
- Ananda J Jadhav
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Mostafa Barigou
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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15
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Azevedo A, Oliveira H, Rubio J. Bulk nanobubbles in the mineral and environmental areas: Updating research and applications. Adv Colloid Interface Sci 2019; 271:101992. [PMID: 31351416 DOI: 10.1016/j.cis.2019.101992] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/09/2019] [Accepted: 07/15/2019] [Indexed: 02/08/2023]
Abstract
In the last decade, the research with bulk nanobubbles (ultrafine bubbles with a diameter <1 μm, according to ISO 20480-1:2017) has been rapidly increasing in the academic and industrial environments. Nowadays, there are many applications reported in the literature, with several patents, procedures, and techniques on nanobubbles generation and an evergrowing research and many applications. Yet, most of those publications reporting bulk nanobubbles generation devices, do not bring information on measurements of size distribution or bubbles concentration (if nanobubbles). Further, there is a problem of scale and many of these products are small bench discontinuous rigs difficult to scale up, which might serve small scale purposes, but are not able for treating high flow-rate wastewaters or minerals pulps at industrial scale. These nanometric bubbles present interesting and peculiar properties such as high surface area per volume unit, high stability and longevity, surface charge in water and the ability to aggregate hydrophobic particles. These findings demonstrate their high potential for applications in many technological areas, which occur not only as isolated bubbles but also jointly with micro (~ 1-100 μm diameter) and/or macrobubbles (~100 μm - 2 mm diameter). This paper reviews the evolution of basic research on nanobubbles, the challenges concerning generation and stability and their applications in the mineral (flotation) and environmental areas (treatment of water and wastewaters or remediation of contaminated environments). Herein, because the importance in engineering, as a whole, most of the studies are based on the nanobubbles generated by depressurisation/hydrodynamic cavitation of the air-saturated water in flow constrictors (venturi, needle valves). In the mineral area, they appear to be responsible for increasing the recovery and flotation kinetics of fine (<74 μm) and ultrafine (<13 μm) particles at lower frother and collector dosages. In the environmental area, nanobubbles have been reported to enhance the removal of a variety of pollutants (emulsified oil, colloidal solids, organic/inorganic precipitates, ions) by flotation associated with bigger bubbles. More, the application of isolated nanobubbles on the removal of residual pollutants, such as amine and oil (both as flocs) were reported. Also, the use of ozone and oxygen nanobubbles has been studied for the remediation/decontamination of soil and aquatic ecosystems and for the oxidation of emerging pollutants in water and wastewater treatment. The future of nanobubbles in flotation separation research is highly promising; operating costs of the different forms of nanobubbles generation and bench studies should be validated through pilot and real scale with the continuous injection of these bubbles.
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16
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Hain N, Handschuh-Wang S, Wesner D, Druzhinin SI, Schönherr H. Multimodal microscopy-based identification of surface nanobubbles. J Colloid Interface Sci 2019; 547:162-170. [PMID: 30952078 DOI: 10.1016/j.jcis.2019.03.084] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/24/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
HYPOTHESIS Surface nanobubbles, which were controversially discussed in the literature, promise a number of outstanding applications, and their presence may hamper nanoscale processes at solid-aqueous interfaces. A most crucial and yet unsolved question is the rapid and conclusive identification of gas-filled (surface) nanobubbles. We hypothesize that surface nanobubbles and oil nanodroplets can be conclusively differentiated in co-localization experiments with atomic force microscopy (AFM) and time-resolved fluorescence microscopy by localizing tracer fluorophores and analyzing their fluorescence lifetimes. EXPERIMENTS Combined AFM and fluorescence lifetime imaging microscopy (FLIM) were conducted to localize the various interfaces labelled by the reporter dye rhodamine 6G (Rh6G). The dependence of the fluorescence lifetime of Rh6G on its local environment was determined for air/water, water/glass and polysiloxane/water interfaces under different conditions. FINDINGS In in situ co-localization experiments, surface nanobubbles labeled with Rh6G were probed by AFM with high spatial resolution and were differentiated from polysiloxane droplets as well as contamination originating from lubricant-coated syringe needles owing to the characteristic short fluorescence lifetime of Rh6G at the gas/water interface observed in FLIM. In particular, this approach lends itself to conclusively identify and rapidly differentiate these gas-filled entities from adsorbed contamination, such as siloxane-based oil nanodroplets.
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Affiliation(s)
- Nicole Hain
- Physical Chemistry I & Research Center of Micro and Nanochemistry and Engineering (Cμ), Department of Chemistry and Biology, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Stephan Handschuh-Wang
- Physical Chemistry I & Research Center of Micro and Nanochemistry and Engineering (Cμ), Department of Chemistry and Biology, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Daniel Wesner
- Physical Chemistry I & Research Center of Micro and Nanochemistry and Engineering (Cμ), Department of Chemistry and Biology, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Sergey I Druzhinin
- Physical Chemistry I & Research Center of Micro and Nanochemistry and Engineering (Cμ), Department of Chemistry and Biology, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Holger Schönherr
- Physical Chemistry I & Research Center of Micro and Nanochemistry and Engineering (Cμ), Department of Chemistry and Biology, School of Science and Technology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
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17
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Wang Y, Chen J, Jiang Y, Wang X, Wang W. Label-Free Optical Imaging of the Dynamic Stick-Slip and Migration of Single Sub-100-nm Surface Nanobubbles: A Superlocalization Approach. Anal Chem 2019; 91:4665-4671. [PMID: 30830757 DOI: 10.1021/acs.analchem.9b00022] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The past decade has witnessed theoretical and experimental debates on the extraordinary long lifetime and low contact angle of surface nanobubbles. While several kinds of imaging techniques have provided promising evidence on the lifetime and gaseous nature of single surface nanobubble, each of them suffered from its own limitations before a consensus can be reached. In the present work, we employ a recently developed surface plasmon resonance microscopy (SPRM) to nonintrusively visualize single sub-100-nm surface nanobubble without labeling for the first time. The quantitative dependence between optical signal and nanobubble volume allows for resolving the dissolution kinetics, which is a key for understanding the lifetime. A superlocalization method is further introduced to monitor the trajectory of its mass center during dissolution, which uncovers the stick-slip behavior in the early stage and the migration behavior in the late stage. The label-free, nonintrusive, quantitative and sensitive features of SPRM and the potential compatibility with atomic force microscopy shed new light on the long-standing puzzle behind surface nanobubbles.
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Affiliation(s)
- Yongjie Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Jing Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Yingyan Jiang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Xian Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Wei Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
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18
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Zhang Z, Guo H, Ma C, Xia M, White JC, Xing B, He L. Rapid and efficient removal of silver nanoparticles from plant surfaces using sodium hypochlorite and ammonium hydroxide solution. Food Control 2019. [DOI: 10.1016/j.foodcont.2018.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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19
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Wang S, Zhou L, Wang X, Wang C, Dong Y, Zhang Y, Gao Y, Zhang L, Hu J. Force Spectroscopy Revealed a High-Gas-Density State near the Graphite Substrate inside Surface Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2498-2505. [PMID: 30645126 DOI: 10.1021/acs.langmuir.8b03383] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The absorption of gas molecules at hydrophobic surfaces may have a special state and play an important role in many processes in interfacial physics, which has been rarely considered in previous theory. In this paper, force spectroscopic experiments were performed by a nanosized AFM probe penetrated into individual surface nanobubbles and contacted with a highly ordered pyrolytic graphite (HOPG) substrate. The results showed that the adhesion force at the gas/solid interface was much smaller than that in air measured with the same AFM probe. The adhesion data were further analyzed by the van der Waals force theory, and the result implied that the gas density near the substrate inside the surface nanobubbles was about 3 orders of magnitude higher than that under the standard pressure and temperature (STP). Our MD simulation indicated that the gas layers near the substrate exhibited a high-density state inside the surface nanobubbles. This high-density state may provide new insight into the understanding of the abnormal stability and contact angle of nanobubbles on hydrophobic surfaces, and have significant impact on their applications.
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Affiliation(s)
- Shuo Wang
- Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
- Institute for Advanced Study , Shenzhen University , Shenzhen 518060 , China
- Key Laboratory of Optoelectronic Devices and System of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering , Shenzhen University , Shenzhen 518060 , China
| | - Limin Zhou
- 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
| | - Xingya Wang
- Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
- Shanghai Synchrotron Radiation Facility , Shanghai 201204 , China
| | - Chunlei Wang
- Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
| | - Yaming Dong
- Shanghai Normal University , Shanghai 200234 , China
| | - Yi Zhang
- Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
| | - Yongxiang Gao
- Institute for Advanced Study , Shenzhen University , Shenzhen 518060 , China
| | - Lijuan Zhang
- Shanghai Synchrotron Radiation Facility , Shanghai 201204 , China
| | - Jun Hu
- Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
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20
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Millare JC, Basilia BA. Nanobubbles from Ethanol-Water Mixtures: Generation and Solute Effects via Solvent Replacement Method. ChemistrySelect 2018. [DOI: 10.1002/slct.201801504] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jeremiah C. Millare
- School of Chemical; Biological; Materials Engineering and Sciences; Mapua University; Muralla Street, Intramuros, Manila Philippines 1002
| | - Blessie A. Basilia
- School of Chemical; Biological; Materials Engineering and Sciences; Mapua University; Muralla Street, Intramuros, Manila Philippines 1002
- Materials Science Division; Industrial Technology Development Institute; Department of Science and Technology; General Santos Avenue, Bicutan, Taguig, Metro Manila Philippines 1631
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21
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Bull DS, Nelson N, Konetski D, Bowman CN, Schwartz DK, Goodwin AP. Contact Line Pinning Is Not Required for Nanobubble Stability on Copolymer Brushes. J Phys Chem Lett 2018; 9:4239-4244. [PMID: 30010342 PMCID: PMC6702125 DOI: 10.1021/acs.jpclett.8b01723] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Whereas nanobubble stability on solid surfaces is thought to be based on local surface structure, in this work, we show that nanobubble stability on polymer brushes does not appear to require contact-line pinning. Glass surfaces were functionalized with copolymer brushes containing mixtures of hydrophobic and hydrophilic segments, exhibiting water contact angles ranging from 10 to 75°. On unmodified glass, dissolution and redeposition of nanobubbles resulted in reformation in mostly the same locations, consistent with the contact line pinning hypothesis. However, on polymer brushes, the nucleation sites were random, and nanobubbles formed in new locations upon redeposition. Moreover, the presence of stable nanobubbles was correlated with global surface wettability, as opposed to local structure, when the surface exceeded a critical water contact angle of 50 or 60° for polymers containing carboxyl or sulfobetaine groups, respectively, as hydrophilic side chains. The critical contact angles were insensitive to the identity of the hydrophobic segments.
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22
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Qiu J, Zou Z, Wang S, Wang X, Wang L, Dong Y, Zhao H, Zhang L, Hu J. Formation and Stability of Bulk Nanobubbles Generated by Ethanol-Water Exchange. Chemphyschem 2017; 18:1345-1350. [PMID: 28258687 DOI: 10.1002/cphc.201700010] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Indexed: 11/06/2022]
Abstract
Bulk nanobubbles have unique properties and find potential applications in many important processes. However, their stability or long lifetime still needs to be understood and has attracted much attention from researchers. Bulk nanobubbles are generated based on ethanol-water exchange, a method that is generally used in the study of surface nanobubbles. Their formation and stability is further studied by using a new type of dynamic light scattering known as NanoSight. The results show that the concentration of the bulk nanobubbles produced by this method is about five times greater than that in the degassed group, which indicates the existence of bulk gas nanobubbles. The effects of ethanol/water ratios and temperature on the stability of the bulk nanobubbles have also been studied and their numbers reach a maximum at a ratio of about 1:10 (v/v).
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Affiliation(s)
- Jie Qiu
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P.R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Zhenglei Zou
- Life and Environment Science College, Shanghai Normal University, Shanghai, 200234, PR China
| | - Shuo Wang
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China
| | - Xingya Wang
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China.,Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, P.R. China
| | - Lei Wang
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China.,Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, P.R. China.,Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha, 610031, P.R. China
| | - Yaming Dong
- Life and Environment Science College, Shanghai Normal University, Shanghai, 200234, PR China
| | - Hongwei Zhao
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China
| | - Lijuan Zhang
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China.,Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, P.R. China
| | - Jun Hu
- Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P.R. China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P.R. China
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23
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Wang L, Wang X, Wang L, Hu J, Wang CL, Zhao B, Zhang X, Tai R, He M, Chen L, Zhang L. Formation of surface nanobubbles on nanostructured substrates. NANOSCALE 2017; 9:1078-1086. [PMID: 27906386 DOI: 10.1039/c6nr06844h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The nucleation and stability of nanoscale gas bubbles located at a solid/liquid interface are attracting significant research interest. It is known that the physical and chemical properties of the solid surface are crucial for the formation and properties of the surface nanobubbles. Herein, we experimentally and numerically investigated the formation of nanobubbles on nanostructured substrates. Two kinds of nanopatterned surfaces, namely, nanotrenches and nanopores, were fabricated using an electron beam lithography technique and used as substrates for the formation of nanobubbles. Atomic force microscopy images showed that all nanobubbles were selectively located on the hydrophobic domains but not on the hydrophilic domains. The sizes and contact angles of the nanobubbles became smaller with a decrease in the size of the hydrophobic domains. The results indicated that the formation and stability of the nanobubbles could be controlled by regulating the sizes and periods of confinement of the hydrophobic nanopatterns. The experimental results were also supported by molecular dynamics simulations. The present study will be very helpful for understanding the effects of surface features on the nucleation and stability of nanobubbles/nanodroplets at a solid/liquid interface.
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Affiliation(s)
- Lei Wang
- Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha 410004, China. and Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Xingya Wang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Liansheng Wang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Jun Hu
- Laboratory of Physical Biology and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Chun Lei Wang
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Binyu Zhao
- Laboratory of Physical Biology and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Xuehua Zhang
- Soft Matter & Interfaces Group, School of Engineering, RMIT University, Melbourne, VIC 3001, Australia
| | - Renzhong Tai
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Mengdong He
- Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha 410004, China.
| | - Liqun Chen
- Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha 410004, China.
| | - Lijuan Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
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24
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Wang L, Miao X, Pan G. Microwave-Induced Interfacial Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11147-11154. [PMID: 27238206 DOI: 10.1021/acs.langmuir.6b01620] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A new method for generating nanobubbles via microwave irradiation was verified and quantified. AFM measurement showed that nanobubbles with diameters ranging from 200 to 600 nm were generated at a water-HOPG surface by applying microwave radiation to aqueous solutions with 9.0-30.0 mg/L dissolved oxygen. Graphite displays strong microwave absorption and transmits high thermal energy to the surface. Because of the high dielectric constant (20 °C, 80 F/m) and dielectric loss factor, water molecules have a strong ability to absorb microwave radiation. The thermal and nonthermal effects of microwave radiation made contributions to decreasing the gas solubility, thus facilitating nanobubble nucleation. The yield of nanobubbles increased about 10-fold when the irradiation time increased from 60 to 120 s at 200 W of microwave radiation. The nanobubble density increased from 0.8 to 15 μm-2 by improving the working power from 200 to 600 W. An apparent improvement in nanobubbles yield was obtained between 300 and 400 W, and the resulting temperature was 34-52 °C. When the initial dissolved oxygen increased from 11.3 to 30.0 mg/L, the density of nanobubbles increased from 1.2 to 13 μm-2. The generation of nanobubbles could be well controlled by adjusting the gas concentration, microwave power, or irradiation time. The method may be valuable in preparing surface nanobubbles quickly and conveniently for various applications, such as catalysis, hypoxia/anoxia remediation, and templates for preparing nanoscale materials.
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Affiliation(s)
- Lei Wang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Xiaojun Miao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Gang Pan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University , Brackenhurst Campus, Southwell NG25 0QF, United Kingdom
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25
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Alheshibri M, Qian J, Jehannin M, Craig VSJ. A History of Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11086-11100. [PMID: 27594543 DOI: 10.1021/acs.langmuir.6b02489] [Citation(s) in RCA: 239] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We follow the history of nanobubbles from the earliest experiments pointing to their existence to recent years. We cover the effect of Laplace pressure on the thermodynamic stability of nanobubbles and why this implies that nanobubbles are thermodynamically never stable. Therefore, understanding bubble stability becomes a consideration of the rate of bubble dissolution, so the dominant approach to understanding this is discussed. Bulk nanobubbles (or fine bubbles) are treated separately from surface nanobubbles as this reflects their separate histories. For each class of nanobubbles, we look at the early evidence for their existence, methods for the production and characterization of nanobubbles, evidence that they are indeed gaseous, or otherwise, and theories for their stability. We also look at applications of both surface and bulk nanobubbles.
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Affiliation(s)
- Muidh Alheshibri
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University , Canberra, ACT 2600, Australia
| | - Jing Qian
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University , Canberra, ACT 2600, Australia
| | - Marie Jehannin
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University , Canberra, ACT 2600, Australia
| | - Vincent S J Craig
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University , Canberra, ACT 2600, Australia
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26
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Song B, Zhou Y, Schönherr H. Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11179-11187. [PMID: 27297734 DOI: 10.1021/acs.langmuir.6b01776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The formation of self-assembled monolayers (SAMs) of binary mixtures of 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on ultraflat template-stripped gold (TSG) surfaces was systematically investigated to clarify the assembly behavior, composition, and degree of possible phase segregation in light of atomic force microscopy (AFM) studies of surface nanobubbles on these substrates. The data for SAMs on TSG were compared to those obtained by adsorption on rough evaporated gold, as reported in a previous study. Quartz crystal microbalance and surface plasmon resonance data acquired in situ on TSG indicate that similar to SAM formation on conventional evaporated gold substrates ODT and MHDA form monolayers and bilayers, respectively. The second layer on MHDA, whose formation is attributed to hydrogen bonding, can be easily removed by adequate rinsing with water. The favorable agreement of the grazing incidence reflection Fourier transform infrared (GIR FTIR) spectroscopy and contact angle data analyzed with the Israelachvili-Gee model suggests that the binary SAMs do not segregate laterally. This conclusion is fully validated by high-resolution friction force AFM observations down to a length scale of 8-10 nm, which is much smaller than the typical observed surface nanobubble radii. Finally, correspondingly functionalized TSG substrates are shown to be valuable supports for studying surface nanobubbles by AFM in water and for addressing the relation between surface functionality and nanobubble formation and properties.
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Affiliation(s)
- Bo Song
- Physical Chemistry I, Department of Chemistry and Biology, and Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
- Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, China
| | - Yi Zhou
- Physical Chemistry I, Department of Chemistry and Biology, and Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
- Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, China
| | - Holger Schönherr
- Physical Chemistry I, Department of Chemistry and Biology, and Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
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27
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Hain N, Wesner D, Druzhinin SI, Schönherr H. Surface Nanobubbles Studied by Time-Resolved Fluorescence Microscopy Methods Combined with AFM: The Impact of Surface Treatment on Nanobubble Nucleation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11155-11163. [PMID: 27268423 DOI: 10.1021/acs.langmuir.6b01662] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The impact of surface treatment and modification on surface nanobubble nucleation in water has been addressed by a new combination of fluorescence lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM). In this study, rhodamine 6G (Rh6G)-labeled surface nanobubbles nucleated by the ethanol-water exchange were studied on differently cleaned borosilicate glass, silanized glass as well as self-assembled monolayers on transparent gold by combined AFM-FLIM. While the AFM data confirmed earlier reports on surface nanobubble nucleation, size, and apparent contact angles in dependence of the underlying substrate, the colocalization of these elevated features with highly fluorescent features observed in confocal intensity images added new information. By analyzing the characteristic contributions to the excited state lifetime of Rh6G in decay curves obtained from time-correlated single photon counting (TCSPC) experiments, the characteristic short-lived (<600 ps) component of could be associated with an emission at the gas-water interface. Its colocalization with nanobubble-like features in the AFM height images provides evidence for the observation of gas-filled surface nanobubbles. While piranha-cleaned glass supported nanobubbles, milder UV-ozone or oxygen plasma treatment afforded glass-water interfaces, where no nanobubbles were observed by combined AFM-FLIM. Finally, the number density of nanobubbles scaled inversely with increasing surface hydrophobicity.
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Affiliation(s)
- Nicole Hain
- Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
| | - Daniel Wesner
- Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
| | - Sergey I Druzhinin
- Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
| | - Holger Schönherr
- Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen , Adolf-Reichwein-Strasse 2, 57076 Siegen, Germany
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Zhao B, Wang X, Wang S, Tai R, Zhang L, Hu J. In situ measurement of contact angles and surface tensions of interfacial nanobubbles in ethanol aqueous solutions. SOFT MATTER 2016; 12:3303-3309. [PMID: 26954468 DOI: 10.1039/c5sm02871j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The astonishing long lifetime and large contact angles of interfacial nanobubbles are still in hot debate despite numerous experimental and theoretical studies. One hypothesis to reconcile the two abnormalities of interfacial nanobubbles is that they have low surface tensions. However, few studies have been reported to measure the surface tensions of nanobubbles due to the lack of effective measurements. Herein, we investigate the in situ contact angles and surface tensions of individual interfacial nanobubbles immersed in different ethanol aqueous solutions using quantitative nanomechanical atomic force microscopy (AFM). The results showed that the contact angles of nanobubbles in the studied ethanol solutions were also much larger than the corresponding macroscopic counterparts on the same substrate, and they decreased with increasing ethanol concentrations. More significantly, the surface tensions calculated were much lower than those of the gas-liquid interfaces of the solutions at the macroscopic scale but have similar tendencies with increasing ethanol concentrations. Those results are expected to be helpful in further understanding the stability of interfacial nanobubbles in complex solutions.
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Affiliation(s)
- Binyu Zhao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
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Chen Q, Luo L, White HS. Electrochemical Generation of a Hydrogen Bubble at a Recessed Platinum Nanopore Electrode. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:4573-81. [PMID: 25811080 DOI: 10.1021/acs.langmuir.5b00234] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We report the electrochemical generation of a single hydrogen bubble within the cavity of a recessed Pt nanopore electrode. The recessed Pt electrode is a conical pore in glass that contains a micrometer-scale Pt disk (1-10 μm radius) at the nanopore base and a nanometer-scale orifice (10-100 nm radius) that restricts diffusion of electroactive molecules and dissolved gas between the nanopore cavity and bulk solution. The formation of a H2 bubble at the Pt disk electrode in voltammetric experiments results from the reduction of H(+) in a 0.25 M H2SO4 solution; the liquid-to-gas phase transformation is indicated in the voltammetric response by a precipitous decrease in the cathodic current due to rapid bubble nucleation and growth within the nanopore cavity. Finite element simulations of the concentration distribution of dissolved H2 within the nanopore cavity, as a function of the H(+) reduction current, indicate that H2 bubble nucleation at the recessed Pt electrode surface occurs at a critical supersaturation concentration of ∼0.22 M, in agreement with the value previously obtained at (nonrecessed) Pt disk electrodes (∼0.25 M). Because the nanopore orifice limits the diffusion of H2 out of the nanopore cavity, an anodic peak corresponding to the oxidation of gaseous and dissolved H2 trapped in the recessed cavity is readily observed on the reverse voltammetric scan. Integration of the charge associated with the H2 oxidation peak is found to approach that of the H(+) reduction peak at high scan rates, confirming the assignment of the anodic peak to H2 oxidation. Preliminary results for the electrochemical generation of O2 bubbles from water oxidation at a recessed nanopore electrode are consistent with the electrogeneration of H2 bubbles.
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Affiliation(s)
- Qianjin Chen
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
| | - Long Luo
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
| | - Henry S White
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
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Walczyk W, Schönherr H. Dimensions and the profile of surface nanobubbles: tip-nanobubble interactions and nanobubble deformation in atomic force microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11955-11965. [PMID: 25222759 DOI: 10.1021/la502918u] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interactions between argon surface nanobubbles and AFM tips on HOPG (highly oriented pyrolitic graphite) in water and the concomitant nanobubble deformation were analyzed as a function of position on the nanobubbles in a combined tapping mode and force-volume mode AFM study with hydrophilic and hydrophobic AFM tips. On the basis of the detailed analysis of force-distance curves acquired on the bubbles, we found that for hydrophobic tips the bubble interface may jump toward the tip and that the tip-bubble interaction strength and the magnitude of the bubble deformation were functions of vertical and horizontal position of the tip on the bubble and depended on the bubble size and tip size and functionality. The spatial variation is attributed to long-range attractive forces originating from the substrate under the bubbles, which dominate the interaction at the bubble rim. The nonuniform bubble deformation leads to a nonuniform underestimation of the bubble height, width, and contact angle in conventional AFM height data. In particular, scanning with a hydrophobic tip resulted in severe bubble deformation and distorted information in the AFM height image. For a typical nanobubble, the upward deformation may extend up to tens of nanometers above the unperturbed bubble height, and the lateral deformation may constitute 20% of the bubble width. Therefore, only scanning with a hydrophilic tip and no direct contact between the tip and the bubble may reduce nanobubble deformation and provide reliable AFM images that can be used to estimate adequately the unperturbed nanobubble dimensions. The deformation of the bubble shape and underestimation of the bubble size lead to the conclusion that the profile of surface nanobubbles is much closer than previously thought to a nearly flat bubble profile and hence that the Laplace pressure is much closer to the atmospheric pressure. Together with line pinning, this may explain the long nanobubble lifetimes observed previously. The findings presented in this report hold independently of the material that constitutes the interrogated nanoscale surface features.
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Affiliation(s)
- Wiktoria Walczyk
- Physical Chemistry I, Department of Chemistry and Biology, University of Siegen , Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
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Walczyk W, Hain N, Schönherr H. Hydrodynamic effects of the tip movement on surface nanobubbles: a combined tapping mode, lift mode and force volume mode AFM study. SOFT MATTER 2014; 10:5945-5954. [PMID: 24988375 DOI: 10.1039/c4sm01024h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report on an Atomic Force Microscopy (AFM) study of AFM tip-nanobubble interactions in experiments conducted on argon surface nanobubbles on HOPG (highly oriented pyrolytic graphite) in water in tapping mode, lift mode and Force Volume (FV) mode AFM. By subsequent data acquisition on the same nanobubbles in these three different AFM modes, we could directly compare the effect of different tip-sample interactions. The tip-bubble interaction strength was found to depend on the vertical and horizontal position of the tip on the bubble with respect to the bubble center. The interaction forces measured experimentally were in good agreement with the forces calculated using the dynamic interaction model. The strength of the hydrodynamic effect was also found to depend on the direction of the tip movement. It was more pronounced in the FV mode, in which the tip approaches the bubble from the top, than in the lift mode, in which the tip approaches the bubble from the side. This result suggests that the direction of tip movement influences the bubble deformation. The effect should be taken into account when nanobubbles are analysed by AFM in various scanning modes.
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Affiliation(s)
- Wiktoria Walczyk
- Physical Chemistry I, University of Siegen, Department of Chemistry and Biology, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
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Ovissipour M, Sablani SS, Rasco B. Engineered nanoparticle adhesion and removal from tomato surfaces. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:10183-10190. [PMID: 24079610 DOI: 10.1021/jf4018228] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Engineered nanoparticles (NPs) are being used in different industries due to their unique physicochemical properties. NPs may be toxic and could pose both public health and environmental contamination risks. In this study, two concentrations (50 and 500 μg mL(-1)) of titania (TiO2), silica (SiO2), and alumina (Al2O3) were applied to contaminate the surface of cherry tomato as a food model, followed by washing with deionized water (DI) to remove the NPs from the tomato surfaces. The NP surface charge and hydrodynamic diameter results showed that the isoelectric point (IEP) for alumina was at pH 9-9.6, for silica at pH <3, and for titania was at pH 6.5-6.8; in addition, the highest hydrodynamic size for all NPs was observed at the IEP. Inductively coupled plasma mass spectrometry (ICP-MS) indicated that the highest NP concentration was observed on tomato surfaces contaminated at the higher concentration (500 μg mL(-1)) (P < 0.05). After the tomatoes had been washed with DI, alumina levels decreased significantly, whereas for titania and silica, no significant difference in NP concentration on tomato surface was observed following the washing treatment. This study shows that removal of NPs may be possible with a simple washing treatment but that removal of NPs is likely to be more effective when the moment ratio is >1, which can occur if the pH of the washing solution is significantly different from the IEP of NPs.
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Affiliation(s)
- Mahmoudreza Ovissipour
- School of Food Science, Washington State University , Pullman, Washington 99164, United States
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Svetovoy VB, Sanders RGP, Elwenspoek MC. Transient nanobubbles in short-time electrolysis. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:184002. [PMID: 23598648 DOI: 10.1088/0953-8984/25/18/184002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Water electrolysis in a microsystem is observed and analyzed on a short-time scale of ∼10 μs. The very unusual properties of the process are stressed. An extremely high current density is observed because the process is not limited by the diffusion of electroactive species. The high current is accompanied by a high relative supersaturation, S > 1000, that results in homogeneous nucleation of bubbles. On the short-time scale only nanobubbles can be formed. These nanobubbles densely cover the electrodes and aggregate at a later time to microbubbles. The effect is significantly intensified with a small increase of temperature. Application of alternating polarity voltage pulses produces bubbles containing a mixture of hydrogen and oxygen. Spontaneous reaction between gases is observed for stoichiometric bubbles with sizes smaller than ∼150 nm. Such bubbles disintegrate violently affecting the surfaces of the electrodes.
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Affiliation(s)
- Vitaly B Svetovoy
- MESA+ Institute for Nanotechnology, University of Twente, PO 217, 7500 AE Enschede, The Netherlands.
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Walczyk W, Schön PM, Schönherr H. The effect of PeakForce tapping mode AFM imaging on the apparent shape of surface nanobubbles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:184005. [PMID: 23598774 DOI: 10.1088/0953-8984/25/18/184005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Until now, TM AFM (tapping mode or intermittent contact mode atomic force microscopy) has been the most often applied direct imaging technique to analyze surface nanobubbles at the solid-aqueous interface. While the presence and number density of nanobubbles can be unequivocally detected and estimated, it remains unclear how much the a priori invasive nature of AFM affects the apparent shapes and dimensions of the nanobubbles. To be able to successfully address the unsolved questions in this field, the accurate knowledge of the nanobubbles' dimensions, radii of curvature etc is necessary. In this contribution we present a comparative study of surface nanobubbles on HOPG (highly oriented pyrolytic graphite) in water acquired with (i) TM AFM and (ii) the recently introduced PFT (PeakForce tapping) mode, in which the force exerted on the nanobubbles rather than the amplitude of the resonating cantilever is used as the AFM feedback parameter during imaging. In particular, we analyzed how the apparent size and shape of nanobubbles depend on the maximum applied force in PFT AFM. Even for forces as small as 73 pN, the nanobubbles appeared smaller than their true size, which was estimated from an extrapolation of the bubble height to zero applied force. In addition, the size underestimation was found to be more pronounced for larger bubbles. The extrapolated true nanoscopic contact angles for nanobubbles on HOPG, measured in PFT AFM, ranged from 145° to 175° and were only slightly underestimated by scanning with non-zero forces. This result was comparable to the nanoscopic contact angles of 160°-175° measured using TM AFM in the same set of experiments. Both values disagree, in accordance with the literature, with the macroscopic contact angle of water on HOPG, measured here to be 63° ± 2°.
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Affiliation(s)
- Wiktoria Walczyk
- Physical Chemistry I, University of Siegen, Adolf-Reichwein-Straße 2, D-57076 Siegen, Germany
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Solubility of gas in confined systems. Nonextensive thermodynamics approach. J Colloid Interface Sci 2013; 392:382-387. [PMID: 23141697 DOI: 10.1016/j.jcis.2012.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 10/02/2012] [Accepted: 10/07/2012] [Indexed: 11/23/2022]
Abstract
The use of the concepts of the nonextensive thermodynamics allows reconsidering the equilibrium of bubble solubilization and more commonly of gaseous aggregates in supersaturated solutions of gas. The introduced relations are general and include as particular cases the equations usually used to describe these phenomena. These equations are discussed. Especially, we specified the domain of application of Kelvin's relation which was illustrated by the solubility of gases in fogs and clouds. Various possibilities of thoughts on the behavior of the gaseous aggregates and nano-systems are proposed. Thus, the introduced relations permit to consider the presence of gaseous aggregates in equilibrium with the solution even for under-saturated solution. Nonextensive thermodynamics admits the notion of negative pressure at the inner of confined phases (solid or liquid).
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Walczyk W, Schönherr H. Closer look at the effect of AFM imaging conditions on the apparent dimensions of surface nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:620-632. [PMID: 23210847 DOI: 10.1021/la304193d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To date, TM AFM (tapping mode or intermittent contact mode atomic force microscopy) is the most frequently applied direct imaging technique to visualize surface nanobubbles at the solid-aqueous interface. On one hand, AFM is the only profilometric technique that provides estimates of the bubbles' nanoscopic dimensions. On the other hand, the nanoscopic contact angles of surface nanobubbles estimated from their apparent dimensions that are deduced from AFM "height" images of nanobubbles differ markedly from the macrocopic water contact angles on the identical substrates. Here we show in detail how the apparent bubble height and width of surface nanobubbles on highly oriented pyrolytic graphite (HOPG) depend on the free amplitude of the cantilever oscillations and the amplitude setpoint ratio. (The role of these two AFM imaging parameters and their interdependence has not been studied so far for nanobubbles in a systematic way.) In all experiments, even with optimal scanning parameters, nanobubbles at the HOPG-water interface appeared to be smaller in the AFM images than their true size, which was estimated using a method presented herein. It was also observed that the severity of the underestimate increased with increasing bubble height and radius of curvature. The nanoscopic contact angle of >130° for nanobubbles on HOPG extrapolated to zero interaction force was only slightly overestimated and hence significantly higher than the macroscopic contact angle of water on HOPG (63 ± 2°). Thus, the widely reported contact angle discrepancy cannot be solely attributed to inappropriate AFM imaging conditions.
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Affiliation(s)
- Wiktoria Walczyk
- Department of Chemistry and Biology, Science & Technology, Physical Chemistry I, University of Siegen, 57076 Siegen, Germany
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Zhang X, Uddin MH, Yang H, Toikka G, Ducker W, Maeda N. Effects of surfactants on the formation and the stability of interfacial nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10471-7. [PMID: 22765767 DOI: 10.1021/la301851g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Contamination has previously been invoked to explain the flat shape and the long lifetimes of interfacial nanobubbles (INBs). In this study, the effects of surfactants on the formation and the stability of INBs were investigated when surfactants were added to the system before, during, and after the standard solvent exchange procedure (SSEP) for the formation of INBs. The solutions of sodium dodecyl sulfate (SDS) above critical micelle concentration were found to have little effect on the bubble stability. Likewise, cleaning of the substrate with a surfactant solution had little effect. In contrast, addition of a water-insoluble surfactant during the formation dramatically reduced the INBs. Finally, repeated application of SSEP to surfactant-coated substrates progressively rinsed the surfactant off the system. Thus, we found no evidence to support the hypothesis that (1) INBs are stabilized by a layer of insoluble organic contaminant or that (2) SSEP introduces surface-active materials to the system that could stabilize INBs.
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Affiliation(s)
- Xuehua Zhang
- Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
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Berkelaar RP, Seddon JRT, Zandvliet HJW, Lohse D. Temperature Dependence of Surface Nanobubbles. Chemphyschem 2012; 13:2213-7. [DOI: 10.1002/cphc.201100808] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 02/24/2012] [Indexed: 11/10/2022]
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Seddon JRT, Lohse D, Ducker WA, Craig VSJ. A deliberation on nanobubbles at surfaces and in bulk. Chemphyschem 2012; 13:2179-87. [PMID: 22378608 DOI: 10.1002/cphc.201100900] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Indexed: 11/11/2022]
Abstract
Surface and bulk nanobubbles are two types of nanoscopic gaseous domain that have recently been discovered in interfacial physics. Both are expected to be unstable to dissolution because of the high internal pressure driving diffusion and the surface tension which squeezes the gas out, but there is a rapidly growing body of experimental evidence that demonstrates both bubble types to be stable. However, the two types of bubbles also differ in many respects: surface nanobubble stability is most probably assisted by the nearby wall, which can repel the water (in the case of hydrophobicity), accept physisorbed gas molecules, and reduce the surface area through which outfluxing can occur; bulk nanobubbles, on the other hand, must stabilise themselves. This is perhaps through ionic shielding, perhaps through diffusive shielding, or perhaps through both. Herein, the features of both bubble types are described individually, their common and disparate features are discussed, and emerging applications are examined.
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Affiliation(s)
- James R T Seddon
- Physics of Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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Wang Z, Etienne M, Pöller S, Schuhmann W, Kohring GW, Mamane V, Walcarius A. Dehydrogenase-Based Reagentless Biosensors: Electrochemically Assisted Deposition of Sol-Gel Thin Films on Functionalized Carbon Nanotubes. ELECTROANAL 2012. [DOI: 10.1002/elan.201100574] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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