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Nanikashvili PM, Butenko AV, Deutsch M, Lee D, Sloutskin E. Salt-induced stability and modified interfacial energetics in self-faceting emulsion droplets. J Colloid Interface Sci 2022; 621:131-138. [PMID: 35487043 DOI: 10.1016/j.jcis.2022.03.146] [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: 03/02/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 10/18/2022]
Abstract
HYPOTHESIS The counterintuitive temperature-controlled self-faceting of water-suspended, surfactant-stabilized, liquid oil droplets provides new opportunities in engineering of smart liquids, the properties of which are controllable by external stimuli. However, many emulsions exhibiting self-faceting phenomena have limited stability due to surfactant precipitation. The emulsions' stability may be enhanced, and their inter-droplet electrostatic repulsion tuned, through controlled charge screening driven by varying-concentration added salts. Moreover, in many technologically-relevant situations, salts may already exist in the emulsion's aqueous phase. Yet, salts' impact on self-faceting effects has never been explored. We hypothesize that the self-faceting transitions' temperatures, and stability against surfactant precipitation, of ionic-surfactants-stabilized emulsions are significantly modified by salt introduction. EXPERIMENTS We explore the temperature-dependent impact of NaCl and CsCl salt concentration on the emulsions' phase diagrams, employing optical microscopy of emulsion droplet shapes and interfacial tension measurements, both sensitive to interfacial phase transitions. FINDINGS A salt concentration dependent increase in the self-faceting transition temperatures is found, and its mechanism elucidated. Our findings allow for a significant enhancement of the emulsions' stability, and provide the physical understanding necessary for future progress in research and applications of self-faceting phenomena in salt-containing emulsions.
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Affiliation(s)
- Pilkhaz M Nanikashvili
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Alexander V Butenko
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Moshe Deutsch
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eli Sloutskin
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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Liu C, Zheng Z, Xi C, Liu Y. Exploration of the natural waxes-tuned crystallization behavior, droplet shape and rheology properties of O/W emulsions. J Colloid Interface Sci 2020; 587:417-428. [PMID: 33370663 DOI: 10.1016/j.jcis.2020.12.024] [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: 05/19/2020] [Revised: 09/28/2020] [Accepted: 12/08/2020] [Indexed: 10/22/2022]
Abstract
Lipid crystallization in O/W emulsions is essential to control the release of nutrients and to food structuring. While few information is involved in adjusting and controlling the performance of emulsions by adjusting oil phase crystallization behavior. We herein developed a novel strategy for designing lipid crystallization inside oil droplets by natural waxes to modify the O/W emulsion properties. Natural waxes, the bio-based and sustainable materials, displayed a high efficiency in modifying the crystallization behavior, droplet surface and shape, as well as the overall performance of emulsions. Specifically, waxes induced the formation of a new hydrocarbon chain distances of 3.70 and 4.15 Å and slightly decreased the lamellar distance (d001) of the single crystallites, thus forming the large and rigid crystals in droplets. Interestingly, these large and rigid crystals in droplets tended to penetrate the interface film, forming the crystal bumps on the droplet surface and facilitating non-spherical shape transformation. The presence of rice bran wax (RW) and carnauba wax (CW) induced the droplet shape into ellipsoid and polyhedron shape, respectively. Furthermore, the uneven interface and non-spherical shape transformation promoted the crystalline droplet-droplet interaction, fabricating a three-dimensional network structure in O/W emulsions. Finally, both linear and nonlinear rheology strongly supported that waxes enhanced the crystalline droplet-droplet interaction and strengthened the network in O/W emulsions. Our findings give a clear insight into the effects of adding natural waxes into oil phase on the crystalline and physical behavior of emulsions, which provides a direction for the design and control of emulsion performance.
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Affiliation(s)
- Chunhuan Liu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China
| | - Zhaojun Zheng
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China
| | - Chang Xi
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China
| | - Yuanfa Liu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China.
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Abdelghafour MM, Deák Á, Mérai L, Ágoston Á, Bélteki R, Sebők D, Dékány I, Janovák L. Photocatalytic elimination of interfacial water pollutants by floatable photoreactive composite nanoparticles. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 266:115285. [PMID: 32805681 DOI: 10.1016/j.envpol.2020.115285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 07/16/2020] [Accepted: 07/18/2020] [Indexed: 06/11/2023]
Abstract
Disastrous oil spills cause severe environmental issues. The shortcomings of current cleaning methods for remediating oil have prompted the latest research drive to create intelligent nanoparticles that absorb oil. We, therefore, synthesized 197 ± 50 nm floatable photoreactive hybrid nanoparticles with Ag-TiO2 plasmonic photocatalyst (Eg = 3.08 eV) content to eliminate interfacial water pollutants, especially toluene-based artificial oil spill. We found that the composite particles have non-wetting properties in the aqueous media and float easily on the surface of the water due to the moderate hydrophobic nature (Θ = 113°) of the matrix of polystyrene, and these properties lead to elevated absorption of the interfacial organic pollutants (e.g., mineral oil). We showed that (28.5 mol%) divinylbenzene cross-linker content was required for adequate swelling capacity (2.15 g/g), whereas incorporated 15.8% Ag-TiO2 content in the swollen particles was enough for efficient photodegradation of the artificial oil spill under 150 min LED light (λmax = 405 nm) irradiation. The swollen polymer particles with embedded 32 ± 7 nm Ag-TiO2 content increase the efficiency of photooxidation by increased the direct contact between both the photocatalysts and the artificial oil spill. Finally, it was also presented that the composite particles destroy themselves: after approximately one and a half months of continuous LED light irradiation, the organic polymer component of the composite was almost completely (88.5%) photodegraded by the incorporated inorganic photocatalyst particles.
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Affiliation(s)
- Mohamed M Abdelghafour
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary; Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, 44519, Egypt
| | - Ágota Deák
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - László Mérai
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - Áron Ágoston
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - Rita Bélteki
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - Dániel Sebők
- University of Szeged, Interdisciplinary Excellence Centre, Department of Applied and Environmental Chemistry, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - Imre Dékány
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary
| | - László Janovák
- University of Szeged, Interdisciplinary Excellence Centre, Department of Physical Chemistry and Materials Science, 6720, Szeged, Rerrich B. Tér 1, Hungary.
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