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Eftekhari M, Schwarzenberger K, Karakashev SI, Grozev NA, Eckert K. Oppositely charged surfactants and nanoparticles at the air-water interface: Influence of surfactant to nanoparticle ratio. J Colloid Interface Sci 2024; 653:1388-1401. [PMID: 37801849 DOI: 10.1016/j.jcis.2023.09.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 08/18/2023] [Accepted: 09/06/2023] [Indexed: 10/08/2023]
Abstract
HYPOTHESIS The interactions between oppositely charged nanoparticles and surfactants can significantly influence the interfacial properties of the system. Traditionally, in the study of such systems, the nanoparticle concentration is varied while the surfactant concentration is kept constant, or vice versa. However, we believe that a defined variation of both components' concentration is necessary to accurately assess their effects on the interfacial properties of the system. We argue that the effect of nanoparticle-surfactant complexes can only be properly evaluated by keeping the surfactant to nanoparticle ratio constant. EXPERIMENTS Zeta potential, dynamic light scattering, high amplitude surface pressure and surface tension measurements are employed synergistically to characterize the interfacial properties of the nanoparticle-surfactant system. Interferometric experiments are performed to highlight the effect of surface concentration on the stability of thin liquid films. FINDINGS The interfacial properties of surfactant/nanoparticle mixtures are primarily determined by the surfactant/nanoparticle ratio. Below a certain ratio, free surfactant molecules are removed from the solution by the formation of surfactant-nanoparticle complexes. Surprisingly, even though the concentration and hydrophobicity of these complexes do not seem to have a noticeable impact on the surface tension, they do significantly affect the rheological properties of the interface. Above this ratio, free surfactant monomers and nanoparticle-surfactant complexes coexist and can co-adsorb at the interface, changing both the interfacial tension and the interfacial rheology, and thus, for example, the foamability and foam stability of the system.
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Affiliation(s)
- Milad Eftekhari
- Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany; Institute of Process Engineering and Environmental Technology, Technische Universität Dresden, Germany.
| | - Karin Schwarzenberger
- Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany; Institute of Process Engineering and Environmental Technology, Technische Universität Dresden, Germany
| | | | - Nikolay A Grozev
- Department of Physical Chemistry, Sofia University, Sofia, Bulgaria
| | - Kerstin Eckert
- Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany; Institute of Process Engineering and Environmental Technology, Technische Universität Dresden, Germany
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Zawala J, Miguet J, Rastogi P, Atasi O, Borkowski M, Scheid B, Fuller GG. Coalescence of surface bubbles: The crucial role of motion-induced dynamic adsorption layer. Adv Colloid Interface Sci 2023; 317:102916. [PMID: 37269558 DOI: 10.1016/j.cis.2023.102916] [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: 03/23/2023] [Revised: 04/27/2023] [Accepted: 04/29/2023] [Indexed: 06/05/2023]
Abstract
The formation of motion-induced dynamic adsorption layers of surfactants at the surface of rising bubbles is a widely accepted phenomenon. Although their existence and formation kinetics have been theoretically postulated and confirmed in many experimental reports, the investigations primarily remain qualitative in nature. In this paper we present results that, to the best of our knowledge, provide a first quantitative proof of the influence of the dynamic adsorption layer on drainage dynamics of a single foam film formed under dynamic conditions. This is achieved by measuring the drainage dynamics of single foam films, formed by air bubbles of millimetric size colliding against the interface between n-octanol solutions and air. This was repeated for a total of five different surfactant concentrations and two different liquid column heights. All three steps preceding foam film rupture, namely the rising, bouncing and drainage steps, were sequentially examined. In particular, the morphology of the single film formed during the drainage step was analyzed considering the rising and bouncing history of the bubble. It was found that, depending on the motion-induced state of adsorption layer at the bubble surface during the rising and the bouncing steps, single foam film drainage dynamics can be spectacularly different. Using Direct Numerical Simulations (DNS), it was revealed that surfactant redistribution can occur at the bubble surface as a result of the bouncing dynamics (approach-bounce cycles), strongly affecting the interfacial mobility, and leading to slower rates of foam film drainage. Since the bouncing amplitude directly depends on the rising velocity, which correlates in turn with the adsorption layer of surfactants at the bubble surface during the rising step, it is demonstrated that the lifetime of surface bubbles should intimately be related to the history of their formation.
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Affiliation(s)
- Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Jonas Miguet
- TIPs, Fluid Physics Unit, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Preetika Rastogi
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Chemical Engineering, Indian Institute of Technology, Chennai 600036, Tamil Nadu, India
| | - Omer Atasi
- TIPs, Fluid Physics Unit, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Mariusz Borkowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Benoit Scheid
- TIPs, Fluid Physics Unit, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Gerald G Fuller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
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Krzan M, Chattopadhyay P, Orvalho S, Zednikova M. Effects of N-Alkanol Adsorption on Bubble Acceleration and Local Velocities in Solutions of the Homologous Series from Ethanol to N-Decanol. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2125. [PMID: 36903239 PMCID: PMC10004471 DOI: 10.3390/ma16052125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/13/2023] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
The influence of n-alkanol (C2-C10) water solutions on bubble motion was studied in a wide range of concentrations. Initial bubble acceleration, as well as local, maximal and terminal velocities during motion were studied as a function of motion time. Generally, two types of velocity profiles were observed. For low surface-active alkanols (C2-C4), bubble acceleration and terminal velocities diminished with the increase in solution concentration and adsorption coverage. No maximum velocities were distinguished. The situation is much more complicated for higher surface-active alkanols (C5-C10). In low and medium solution concentrations, bubbles detached from the capillary with acceleration comparable to gravitational acceleration, and profiles of the local velocities showed maxima. The terminal velocity of bubbles decreased with increasing adsorption coverage. The heights and widths of the maximum diminished with increasing solution concentration. Much lower initial acceleration values and no maxima presence were observed in the case of the highest n-alkanol concentrations (C5-C10). Nevertheless, in these solutions, the observed terminal velocities were significantly higher than in the case of bubbles moving in solutions of lower concentration (C2-C4). The observed differences were explained by different states of the adsorption layer in the studied solutions, leading to varying degrees of immobilization of the bubble interface, which generates other hydrodynamic conditions of bubble motion.
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Affiliation(s)
- Marcel Krzan
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30-239 Krakow, Poland
| | | | - Sandra Orvalho
- Institute of Chemical Process Fundamentals of the CAS, Rozvojová 1, 165 00 Prague, Czech Republic
| | - Maria Zednikova
- Institute of Chemical Process Fundamentals of the CAS, Rozvojová 1, 165 00 Prague, Czech Republic
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Luo Y, Wang Z, Zhang B, Guo K, Zheng L, Xiang W, Liu H, Liu C. Experimental Study of the Effect of the Surfactant on the Single Bubble Rising in Stagnant Surfactant Solutions and a Mathematical Model for the Bubble Motion. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c01620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yi Luo
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Zhengchao Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Bo Zhang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Kai Guo
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Longyun Zheng
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Wenyu Xiang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Hui Liu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Chunjiang Liu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China
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Hamdollahi E, Lotfi M, Shafiee M, Hemmati A. Investigation of antibiotic surface activity by tracking hydrodynamic of a rising bubble. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2021.12.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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6
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Fayzi P, Bastani D, Lotfi M, Miller R. Influence of Surface‐Modified Nanoparticles on the Hydrodynamics of Rising Bubbles. Chem Eng Technol 2021. [DOI: 10.1002/ceat.201900234] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Pouyan Fayzi
- Sharif University of Technology Chemical & Petroleum Engineering Department 11155-9567 Tehran Iran
| | - Dariush Bastani
- Sharif University of Technology Chemical & Petroleum Engineering Department 11155-9567 Tehran Iran
| | - Marzieh Lotfi
- Jundi-Shapur University of Technology Department of Chemical Engineering 64615/334 Dezful Iran
| | - Reinhard Miller
- Technical University of Darmstadt Physics Department 64289 Darmstadt Germany
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7
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Effect of initial adsorption coverage and dynamic adsorption layer formation at bubble surface in stability of single foam films. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.124446] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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8
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Zawala J, Malysa K, Kowalczuk PB. On importance of external conditions and properties of the interacting phases in formation and stability of symmetrical and unsymmetrical liquid films. Adv Colloid Interface Sci 2020; 276:102085. [PMID: 31887573 DOI: 10.1016/j.cis.2019.102085] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 11/30/2022]
Abstract
Importance of external conditions and properties of phases creating liquid films, in outcome of the air bubble collisions with liquid/air and liquid/solids interfaces in clean water and in liquid solutions, is critically reviewed. The review is focussed on initial stages of the liquid films formation by bubbles colliding with interfaces, as well as, on analysis of the most important factors responsible for the collision's outcome, that is, either the rapid bubble bouncing or formation of the symmetrical or unsymmetrical liquid films and their thinning to the critical rupture thicknesses. Data on formation of liquid films under dynamic conditions, both in pure liquids and solutions of electrolytes and various surface-active substances, are reviewed and importance of hydrodynamic boundary conditions at interacting interfaces for energy balance in the system is discussed. It is shown that the liquid films stability, which in stagnant systems are directly determined by properties of the liquid/gas and liquid/solid interfaces, can be quite different in dynamic environment. A mechanism of the bubble bouncing from various interfaces in terms of interplay between energy exchange and kinetics of liquid film drainage is analyzed. It is shown that this mechanism is universal and irrelevant on the nature of interacting phases. Moreover, mechanisms responsible for wetting (unsymmetrical) film stability under dynamic conditions are discussed in light of the most recent studies, showing a crucial role of electrolyte, kind and concentration of surface-active substances, electrical surface charge, hydrophilic/hydrophobic properties of solids and presence of air entrapped (nano- and/or micro-bubbles) at surfaces of highly hydrophobic solids in the liquid films rupture.
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Affiliation(s)
- Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland.
| | - Kazimierz Malysa
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Przemyslaw B Kowalczuk
- Norwegian University of Science and Technology, Department of Geoscience and Petroleum, S. P. Andersens veg 15a, 7031 Trondheim, Norway
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Dabestani M, Yeganehzad S, Krzan M, Miller R. Characterisation of egg white adsorption layers under equilibrium and dynamic conditions. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.01.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Llamas S, Santini E, Liggieri L, Salerni F, Orsi D, Cristofolini L, Ravera F. Adsorption of Sodium Dodecyl Sulfate at Water-Dodecane Interface in Relation to the Oil in Water Emulsion Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5978-5989. [PMID: 29718671 DOI: 10.1021/acs.langmuir.8b00358] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The control of the behavior of oil in water emulsions requires deeper investigations on the adsorption properties of the emulsion stabilizers at the interfaces, which are fundamental to explain the (de)stabilization mechanisms. In this work, we present an extensive study on oil-in-water emulsions stabilized by sodium dodecyl sulfate (SDS) below its critical micellar concentration. Dynamic tensiometry, dilational rheology, and electrical conductivity measurements are used to investigate the adsorption properties at the droplet interface, whereas the aging of the respective emulsions was investigated by monitoring the macroscopic thickness of the emulsion layer, by microimaging and dynamic light scattering (DLS) analysis, to get information on the drop size distribution. In addition, the droplet coalescence is investigated by a microscopy setup. The results of this multitechnique study allow deriving a coherent scenario where the adsorption properties of this ionic surfactant relate to those of the emulsion, such as, for example, the prevention of droplet coalescence and the presence of other mechanisms, such as Ostwald ripening, responsible for the emulsion aging.
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Affiliation(s)
- Sara Llamas
- CNR-Institute of Condensed Matter Chemistry and Technologies for Energy , Via de Marini 6 , 16149 Genoa , Italy
| | - Eva Santini
- CNR-Institute of Condensed Matter Chemistry and Technologies for Energy , Via de Marini 6 , 16149 Genoa , Italy
| | - Libero Liggieri
- CNR-Institute of Condensed Matter Chemistry and Technologies for Energy , Via de Marini 6 , 16149 Genoa , Italy
| | - Fabrizia Salerni
- Department of Mathematical, Physical and Computer Sciences , University of Parma , Viale Usberti 7 A , 43124 Parma , Italy
| | - Davide Orsi
- Department of Mathematical, Physical and Computer Sciences , University of Parma , Viale Usberti 7 A , 43124 Parma , Italy
| | - Luigi Cristofolini
- CNR-Institute of Condensed Matter Chemistry and Technologies for Energy , Via de Marini 6 , 16149 Genoa , Italy
- Department of Mathematical, Physical and Computer Sciences , University of Parma , Viale Usberti 7 A , 43124 Parma , Italy
| | - Francesca Ravera
- CNR-Institute of Condensed Matter Chemistry and Technologies for Energy , Via de Marini 6 , 16149 Genoa , Italy
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12
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Yan X, Zheng K, Jia Y, Miao Z, Wang L, Cao Y, Liu J. Drag Coefficient Prediction of a Single Bubble Rising in Liquids. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.7b04743] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaokang Yan
- School of Chemical Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Kaixin Zheng
- School of Electric Power Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Yan Jia
- School of Electric Power Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
- Department of Mechanical and Electrical Engineering, Beijing Jiaotong University Haibin College, Huanghua, Hebei 061199, China
| | - Zhenyong Miao
- School of Chemical Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Lijun Wang
- School of Electric Power Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Yijun Cao
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Jiongtian Liu
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
- School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou, Henan 450001, China
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Kosior D, Zawala J. Initial degree of detaching bubble adsorption coverage and the kinetics of dynamic adsorption layer formation. Phys Chem Chem Phys 2018; 20:2403-2412. [DOI: 10.1039/c7cp06099h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We show, for the first time, the influence of the initial adsorption coverage over a bubble on the kinetics of dynamic adsorption layer formation.
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Affiliation(s)
- Dominik Kosior
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences
- Krakow
- Poland
| | - Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences
- Krakow
- Poland
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Zawala J, Niecikowska A. "Bubble-on-demand" generator with precise adsorption time control. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:095106. [PMID: 28964187 DOI: 10.1063/1.5001846] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The paper presents the principles of our new single bubble generator, which allows a precise control of bubble formation in pure liquids and surfactant solutions, i.e., their detachment frequency and the adsorption time at their motionless surface. We show that the bubbles with equilibrium size can be produced at the capillaries of various orifice diameters (0.022-0.128 mm) on demand and with outstanding reproducibility. Moreover, it is shown that a fully automatized and programmable bubble trap, synchronized with bubble detachment frequency, can be used to (i) control the radius of the released bubble and (ii) precisely adjust the initial adsorption coverage over the surface of detaching bubble, and hence to study the influence of adsorption coverage degree on kinetics of dynamic adsorption layer formation at the rising bubble surface.
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Affiliation(s)
- J Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Krakow, Poland
| | - A Niecikowska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Krakow, Poland
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Ulaganathan V, Gochev G, Gehin-Delval C, Leser M, Gunes D, Miller R. Effect of pH and electrolyte concentration on rising air bubbles in β-lactoglobulin solutions. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.03.059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Jarek E, Warszynski P, Krzan M. Influence of different electrolytes on bubble motion in ionic surfactants solutions. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.03.071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dynamics of rear stagnant cap formation at the surface of rising bubbles in surfactant solutions at large Reynolds and Marangoni numbers and for slow sorption kinetics. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2015.12.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Dukhin S, Kovalchuk V, Gochev G, Lotfi M, Krzan M, Malysa K, Miller R. Dynamics of Rear Stagnant Cap formation at the surface of spherical bubbles rising in surfactant solutions at large Reynolds numbers under conditions of small Marangoni number and slow sorption kinetics. Adv Colloid Interface Sci 2015; 222:260-74. [PMID: 25455807 DOI: 10.1016/j.cis.2014.10.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/03/2014] [Accepted: 10/05/2014] [Indexed: 10/24/2022]
Abstract
On the surface of bubbles rising in a surfactant solution the adsorption process proceeds and leads to the formation of a so called Rear Stagnant Cap (RSC). The larger this RSC is the stronger is the retardation of the rising velocity. The theory of a steady RSC and steady retarded rising velocity, which sets in after a transient stage, has been generally accepted. However, a non-steady process of bubble rising starting from the initial zero velocity represents an important portion of the trajectory of rising, characterized by a local velocity profile (LVP). As there is no theory of RSC growth for large Reynolds numbers Re » 1 so far, the interpretation of LVPs measured in this regime was impossible. It turned out, that an analytical theory for a quasi-steady growth of RSC is possible for small Marangoni numbers Ma « 1, i.e. when the RSC is almost completely compressed, which means a uniform surface concentration Γ(θ)=Γ(∞) within the RSC. Hence, the RSC angle ψ(t) is obtained as a function of the adsorption isotherm parameters and time t. From the steady velocity v(st)(ψ), the dependence of non-steady velocity on time is obtained by employing v(st)[ψ(t)] via a quasi-steady approximation. The measurement of LVP creates a promising new opportunity for investigation of the RSC dynamics and adsorption kinetics. While adsorption and desorption happen at the same localization in the classical methods, in rising bubble experiments desorption occurs mainly within RSC while adsorption on the mobile part of the bubble surface. The desorption flux from RSC is proportional to αΓ(∞), while it is usually αΓ. The adsorption flux at the mobile surface above RSC can be assumed proportional to βC0, while it is usually βC0(1-Γ/Γ(∞)). These simplifications may become favorable in investigations of the adsorption kinetics for larger molecules, in particular for globular proteins, which essentially stay at an interface once adsorbed.
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Formation and influence of the dynamic adsorption layer on kinetics of the rising bubble collisions with solution/gas and solution/solid interfaces. Adv Colloid Interface Sci 2015; 222:765-78. [PMID: 25147100 DOI: 10.1016/j.cis.2014.07.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 07/29/2014] [Indexed: 11/23/2022]
Abstract
BACKGROUND The DAL (dynamic adsorption layer) formation, that is, the establishment of uneven distribution of adsorption coverage over the rising bubble surface, with significantly diminished coverage at the upstream pole, is the factor of crucial importance for the bubble motion parameters and kinetic of the bubble collisions with various interfaces. The DAL presence can influence the stability of the thin liquid films formed by the colliding bubble at solution/gas and solution solid interfaces. AIM The purpose of this paper is to critically review the existing state of art regarding the influence of the DAL formation and existence on the bubble motion parameters as well as kinetics of coalescence at free solution surface and three phase contact (TPC) formation at solid/liquid interfaces of different hydrophilic/hydrophobic properties. CONCLUSIONS Despite the fact that up to now there is no direct experimental evidence showing DAL existence, it is documented by experimental data showing clear correlation between bubble local velocity variations and shape pulsations as well as lifetimes of the liquid film formed by the colliding bubble at gas/liquid and gas/solid interfaces.
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Dan A, Gochev G, Miller R. Tensiometry and dilational rheology of mixed β-lactoglobulin/ionic surfactant adsorption layers at water/air and water/hexane interfaces. J Colloid Interface Sci 2015; 449:383-91. [DOI: 10.1016/j.jcis.2015.01.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/13/2015] [Accepted: 01/14/2015] [Indexed: 11/29/2022]
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