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Norouzi Darabad M, Singha S, Vanapalli SA, Vaughn MW, Blawzdziewicz J. Capillary imbibition of confined monodisperse emulsions in microfluidic channels. SOFT MATTER 2024; 20:4337-4357. [PMID: 38639811 DOI: 10.1039/d4sm00179f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
We study imbibition of a monodisperse emulsion into high-aspect ratio microfluidic channels with the height h comparable to the droplet diameter d. Two distinct regimes are identified in the imbibition dynamics. In a strongly confined system (the confinement ratio d/h = 1.2 in our experiments), the droplets are flattened between the channel walls and move more slowly compared to the average suspension velocity. As a result, a droplet-free region forms behind the meniscus (separated from the suspension region by a sharp concentration front) and the suspension exhibits strong droplet-density and velocity fluctuations. In a weaker confinement, d/h = 0.65, approximately spherical droplets move faster than the average suspension flow, causing development of a dynamically unstable high-concentration region near the meniscus. This instability results in the formation of dense droplet clusters, which migrate downstream relative to the average suspension flow, thus affecting the entire suspension dynamics. We explain the observed phenomena using linear transport equations for the particle-phase and suspension fluxes driven by the local pressure gradient. We also use a dipolar particle interaction model to numerically simulate the imbibition dynamics. The observed large velocity fluctuations in strongly confined systems are elucidated in terms of migration of self-assembled particle chains with highly anisotropic mobility.
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Affiliation(s)
- Masoud Norouzi Darabad
- Department of Chemical Engineering, Texas Tech University, Box 43121, Lubbock, TX 79409, USA.
| | - Sagnik Singha
- Department of Mechanical Engineering, Texas Tech University, Box 41021, Lubbock, TX 79409, USA.
| | - Siva A Vanapalli
- Department of Chemical Engineering, Texas Tech University, Box 43121, Lubbock, TX 79409, USA.
| | - Mark W Vaughn
- Department of Chemical Engineering, Texas Tech University, Box 43121, Lubbock, TX 79409, USA.
| | - Jerzy Blawzdziewicz
- Department of Mechanical Engineering, Texas Tech University, Box 41021, Lubbock, TX 79409, USA.
- Department of Physics and Astronomy, Texas Tech University, Box 41051, Lubbock, TX 79409, USA
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2
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Zheng D, Guan W, Chen J, Zeng C, Tan S, Chen J, Ma D. Sucrose Stearates Stabilized Oil-in-Water Emulsions: Gastrointestinal Fate, Cell Cytotoxicity and Proinflammatory Effects after Simulated Gastrointestinal Digestion. Foods 2024; 13:175. [PMID: 38201202 PMCID: PMC10778613 DOI: 10.3390/foods13010175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/27/2023] [Accepted: 12/29/2023] [Indexed: 01/12/2024] Open
Abstract
Different structural composition ratios of sucrose stearates with hydrophilic-hydrophobic balance (HLB) values ranging from 1 to 16 on lipolysis in emulsion were investigated using a simulated gastrointestinal tract (GIT). Results showed a direct correlation between the HLB values of sucrose stearates and the lipolysis rate of emulsions, and a lower HLB value led to diminished lipolysis in the GIT simulation model. Mechanism study indicated that poor emulsifying capacity of sucrose stearates and lipolysis of sucrose stearates with lower HLB value inhibited the digestive behavior of oil. In addition, monoester was mainly hydrolyzed in the gastric phase, whereas sucrose polyesters caused lipolysis in the intestinal phase using an in vitro digestive model and HPLC analysis, further suppressing lipid digestion. Furthermore, a decrease in cell cytotoxicity and proinflammatory effects on Caco-2 and Raw264.7 were observed post-digestion, respectively. This work offers important insights into the effects of the degree of esterification of sucrose stearate on lipid digestion behavior in oil-in-water emulsions.
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Affiliation(s)
- Danhong Zheng
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Guangzhou 510632, China
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Weiyan Guan
- College of Packaging Engineering, Jinan University, Zhuhai 519070, China
| | - Jiaqing Chen
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Guangzhou 510632, China
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Cuicui Zeng
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Guangzhou 510632, China
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Shen Tan
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Guangzhou 510632, China
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Jing Chen
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Guangzhou 510632, China
- College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Da Ma
- College of Packaging Engineering, Jinan University, Zhuhai 519070, China
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3
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Deng B, Schroën K, de Ruiter J. Dynamics of bubble formation in spontaneous microfluidic devices: Controlling dynamic adsorption via liquid phase properties. J Colloid Interface Sci 2022; 622:218-227. [DOI: 10.1016/j.jcis.2022.04.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022]
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4
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Zhang L, Wang K, An H, Su Y, Zhang W, Li G, Yang X. Testing and Evaluation of the Emulsifying Properties of Compound Oil Displacement Agents. ACS OMEGA 2022; 7:29406-29414. [PMID: 36033671 PMCID: PMC9404487 DOI: 10.1021/acsomega.2c03653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Aiming at the phenomenon that the emulsification degree of the composite oil displacement agents affects the recovery factor, composite oil displacement agents of the P/S binary system and the A/S/P ternary system were taken as research objects. Emulsion particle size and stability were tested and evaluated, and the effects of the surfactant and alkali content on the emulsification degree of emulsion were investigated. The concept of the emulsification stability index and its measuring method were put forward, and a method was used to test and evaluate the emulsification stability of the emulsion. The results showed that the emulsion formed by the ternary system had the smallest average particle size, the best stability, and the best emulsification stability. The binary composite system was second, and the polymer solution did not form an emulsion. The emulsification stability index method could effectively quantify the emulsification degree of the emulsion. Within a certain range, the increase of the surfactant and alkali content in the composite oil displacement agent was beneficial to the improvement of the emulsification degree of the emulsion.
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Affiliation(s)
- Leilei Zhang
- Key
Laboratory of Enhanced Oil and Gas Recovery Ministry of Education, Northeast Petroleum University, Daqing 163318, China
- Baili
College of Petroleum Engineering, Lanzhou
City University, Lanzhou 730070, China
| | - Keliang Wang
- Key
Laboratory of Enhanced Oil and Gas Recovery Ministry of Education, Northeast Petroleum University, Daqing 163318, China
| | - Huiming An
- Baili
College of Petroleum Engineering, Lanzhou
City University, Lanzhou 730070, China
| | - Yu Su
- Key
Laboratory of Enhanced Oil and Gas Recovery Ministry of Education, Northeast Petroleum University, Daqing 163318, China
| | - Wei Zhang
- Key
Laboratory of Enhanced Oil and Gas Recovery Ministry of Education, Northeast Petroleum University, Daqing 163318, China
| | - Gen Li
- Key
Laboratory of Enhanced Oil and Gas Recovery Ministry of Education, Northeast Petroleum University, Daqing 163318, China
| | - Xinyi Yang
- Baili
College of Petroleum Engineering, Lanzhou
City University, Lanzhou 730070, China
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5
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Interface evolution and pinch-off mechanism of droplet in two-phase liquid flow through T-junction microfluidic system. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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6
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Ho TM, Razzaghi A, Ramachandran A, Mikkonen KS. Emulsion characterization via microfluidic devices: A review on interfacial tension and stability to coalescence. Adv Colloid Interface Sci 2022; 299:102541. [PMID: 34920366 DOI: 10.1016/j.cis.2021.102541] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/22/2021] [Accepted: 10/03/2021] [Indexed: 01/29/2023]
Abstract
Emulsions have gained significant importance in many industries including foods, pharmaceuticals, cosmetics, health care formulations, paints, polymer blends and oils. During emulsion generation, collisions can occur between newly-generated droplets, which may lead to coalescence between the droplets. The extent of coalescence is driven by the properties of the dispersed and continuous phases (e.g. density, viscosity, ion strength and pH), and system conditions (e.g. temperature, pressure or any external applied forces). In addition, the diffusion and adsorption behaviors of emulsifiers which govern the dynamic interfacial tension of the forming droplets, the surface potential, and the duration and frequency of the droplet collisions, contribute to the overall rate of coalescence. An understanding of these complex behaviors, particularly those of interfacial tension and droplet coalescence during emulsion generation, is critical for the design of an emulsion with desirable properties, and for the optimization of the processing conditions. However, in many cases, the time scales over which these phenomena occur are extremely short, typically a fraction of a second, which makes their accurate determination by conventional analytical methods extremely challenging. In the past few years, with advances in microfluidic technology, many attempts have demonstrated that microfluidic systems, characterized by micrometer-size channels, can be successfully employed to precisely characterize these properties of emulsions. In this review, current applications of microfluidic devices to determine the equilibrium and dynamic interfacial tension during droplet formation, and to investigate the coalescence stability of dispersed droplets applicable to the processing and storage of emulsions, are discussed.
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7
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Park D, Kim H, Kim JW. Microfluidic production of monodisperse emulsions for cosmetics. BIOMICROFLUIDICS 2021; 15:051302. [PMID: 34733378 PMCID: PMC8550801 DOI: 10.1063/5.0057733] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 10/11/2021] [Indexed: 05/06/2023]
Abstract
Droplet-based microfluidic technology has enabled the production of emulsions with high monodispersity in sizes ranging from a few to hundreds of micrometers. Taking advantage of this technology, attempts to generate monodisperse emulsion drops with high drug loading capacity, ordered interfacial structure, and multi-functionality have been made in the cosmetics industry. In this article, we introduce the practicality of the droplet-based microfluidic approach to the cosmetic industry in terms of innovation in productivity and marketability. Furthermore, we summarize some recent advances in the production of emulsion drops with enhanced mechanical interfacial stability. Finally, we discuss the future prospects of microfluidic technology in accordance with consumers' needs and industrial attributes.
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Affiliation(s)
- Daehwan Park
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Hajeong Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jin Woong Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
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Porto Santos T, Cejas CM, Cunha RL, Tabeling P. Unraveling driving regimes for destabilizing concentrated emulsions within microchannels. SOFT MATTER 2021; 17:1821-1833. [PMID: 33399611 DOI: 10.1039/d0sm01674h] [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
Coalescence is the most widely demonstrated mechanism for destabilizing emulsion droplets in microfluidic chambers. However, we find that depending on the channel wall surface functionalization, surface zeta potential, type of surfactant, characteristics of the oil as a dispersed phase, or even the presence of externally-induced stress, other different destabilization mechanisms can occur in subtle ways. In general, we observe four regimes leading to destabilization of concentrated emulsions: (i) coalescence, (ii) emulsion bursts, (iii) a combination of the two first mechanisms, attributed to the simultaneous occurrence of coalescence and emulsion bursts; and (iv) compaction of the droplet network that eventually destabilizes to fracture-like behavior. We correlate various physico-chemical properties (zeta potential, contact angle, interfacial tension) to understand their respective influence on the destabilization mechanisms. This work provides insights into possible ways to control or inflict emulsion droplet destabilization for different applications.
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Affiliation(s)
- Tatiana Porto Santos
- Department of Food Engineering, Faculty of Food Engineering, University of Campinas, Rua Monteiro Lobato, 80-CEP 13083-862 Campinas, Brazil. and Microfluidics, MEMS, Nanostructures Laboratory, CNRS Chimie Biologie Innovation (CBI) UMR 8231, Institut Pierre Gilles de Gennes (IPGG), ESPCI Paris, PSL Research University, 6 rue Jean Calvin 75005, Paris, France.
| | - Cesare M Cejas
- Microfluidics, MEMS, Nanostructures Laboratory, CNRS Chimie Biologie Innovation (CBI) UMR 8231, Institut Pierre Gilles de Gennes (IPGG), ESPCI Paris, PSL Research University, 6 rue Jean Calvin 75005, Paris, France.
| | - Rosiane Lopes Cunha
- Department of Food Engineering, Faculty of Food Engineering, University of Campinas, Rua Monteiro Lobato, 80-CEP 13083-862 Campinas, Brazil.
| | - Patrick Tabeling
- Microfluidics, MEMS, Nanostructures Laboratory, CNRS Chimie Biologie Innovation (CBI) UMR 8231, Institut Pierre Gilles de Gennes (IPGG), ESPCI Paris, PSL Research University, 6 rue Jean Calvin 75005, Paris, France.
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9
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Yulianingsih R, Gohtani S. The influence of stirring speed and type of oil on the performance of pregelatinized waxy rice starch emulsifier in stabilizing oil-in-water emulsions. J FOOD ENG 2020. [DOI: 10.1016/j.jfoodeng.2020.109920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Abedi S, Chen CC, Vanapalli SA. Catastrophic thermal destabilization of two-dimensional close-packed emulsions due to synchronous coalescence initiation. SOFT MATTER 2020; 16:6032-6037. [PMID: 32519709 DOI: 10.1039/d0sm00649a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The mechanisms for phase separation in highly concentrated emulsions when subjected to a thermal phase transition remain to be elucidated. Here, we create a hexagonally close-packed monodisperse emulsion in 2D and show that during a cool-heat cycle, the emulsion fully destabilizes akin to phase separation. The mechanism for this catastrophic destabilization is found to be spontaneous coalescence initiation that synchronously occurs between every solidified droplet and its neighbors. This synchronous coalescence initiation establishes system-wide network connectivity in the emulsion causing large-scale destabilization. This system-wide coalescence initiation is found to be insensitive to droplet size and tested surfactants, but dependent on network connectivity and crystal content of individual droplets.
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Affiliation(s)
- Samira Abedi
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USA.
| | - Chau-Chyun Chen
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USA.
| | - Siva A Vanapalli
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USA.
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11
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Thiel A, Atherton TJ, Spicer PT, Hartel RW. Aggregation in viscoelastic emulsion droplet gels with capillarity-driven rearrangements. SOFT MATTER 2020; 16:5506-5513. [PMID: 32495759 DOI: 10.1039/c9sm02134e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Arrested, or partial, coalescence of viscoelastic emulsion droplets can occur when elastic resistance to deformation offsets droplet surface area minimization. Arrest is a critical element of food and consumer product microstructure and performance, but direct studies of structural arrest and rearrangement have been carried out using only two or three droplets at a time. The question remains whether the behavior of small numbers of droplets also occurs in larger, more realistic many-droplet systems. Here we study two-dimensional aggregation and arrested coalescence of emulsions containing ∼1000 droplets and find that the restructuring mechanisms observed for smaller systems have a large effect on local packing in multidroplet aggregates, but surprisingly do not significantly alter overall mass scaling in the aggregates. Specifically, increased regions of hexagonal packing are observed as the droplet solids level, and thus elasticity, is decreased because greater degrees of capillary force-driven restructuring are possible. Diffusion-limited droplet aggregation simulations that account for the restructuring mechanisms agree with the experimental results and suggest a basis for prediction of larger-scale network properties and bulk emulsion behavior.
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Affiliation(s)
- Abigail Thiel
- Department of Food Science, University of Wisconsin-Madison, Madison, WI, USA
| | | | | | - Richard W Hartel
- Department of Food Science, University of Wisconsin-Madison, Madison, WI, USA
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12
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Abedi S, Chen CC, Vanapalli SA. Collective nucleation dynamics in two-dimensional emulsions with hexagonal packing. Phys Rev E 2020; 101:030602. [PMID: 32289965 DOI: 10.1103/physreve.101.030602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/09/2020] [Indexed: 01/22/2023]
Abstract
We report a mechanism for nucleation in a monolayer of hexagonally packed monodisperse droplet arrays. Upon cooling, we observe solidified droplets to nucleate their supercooled neighbors giving rise to an autocatalyticlike mechanism for accelerated crystallization. This collective mode of nucleation depends on the strength and nature of droplet contacts. Intriguingly, the statistical distribution of the solidified droplet clusters is found to be independent of emulsion characteristics except surfactant. In contrast to classical nucleation theory, our work highlights the need to consider collective effects of nucleation in supercooled concentrated emulsions where droplet crowding is inevitable.
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Affiliation(s)
- Samira Abedi
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409-3121, USA
| | - Chau-Chyun Chen
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409-3121, USA
| | - Siva A Vanapalli
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409-3121, USA
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13
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Lee SJ, Kang JY, Choi W, Kwak R. Simultaneous electric production and sizing of emulsion droplets in microfluidics. SOFT MATTER 2020; 16:614-622. [PMID: 31774108 DOI: 10.1039/c9sm01426h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microscale emulsions are widely used in fundamental and applied sciences. To expand their utilization, various methods have been developed for manipulating and measuring the physical properties of fabricated emulsions inside microchannels. Herein, we present an electric emulsification platform that can produce emulsions and simultaneously detect their physical properties (size and production speed). The characterization of the emulsion properties during the fabrication process will broaden the application fields for microscale emulsions because it can avoid time-consuming post image processing and simplify the emulsification platform. To accomplish this, a "bottleneck" channel is implanted between two reservoirs of immiscible fluids (continuous and dispersion phases). This channel can not only confine one fluid within the other when the electric field is on, resulting in emulsification via electrohydrodynamically induced Rayleigh instability, but also act as a resistive pulse sensor (RPS). The fluctuation of the liquid/liquid interface during emulsification induces the fluctuation of the electric resistance in the bottleneck channel, as the two fluid phases have different electrical conductivities. With this simple but dual-functional channel, the emulsion size (radius of 5-10 μm) and production speed (7-12 Hz) can be controlled by adjusting the electric field and the channel-neck geometry. Additionally, the properties can be measured using the RPS; the data obtained through the RPS exhibit high correlations with the validated data obtained using a high-speed camera and microscopy (>95%). The proposed buffer-less electric emulsification with the embedded RPS is a simple and cost-effective emulsion production method that allows real-time emulsion characterization with a limited sample volume.
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Affiliation(s)
- Sang Jun Lee
- Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul, 02792, Korea
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14
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Church J, Lundin JG, Diaz D, Mercado D, Willner MR, Lee WH, Paynter DM. Identification and characterization of bilgewater emulsions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 691:981-995. [PMID: 31326820 DOI: 10.1016/j.scitotenv.2019.06.510] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/28/2019] [Accepted: 06/29/2019] [Indexed: 06/10/2023]
Abstract
Literature on bilgewater focuses on empirically determined treatment methods and lacks specific information on emulsion characteristics. Therefore, this review discusses potential emulsion stabilization mechanisms that occur in bilgewater and evaluates common approaches to study their behavior. Current knowledge on emulsion formation, stabilization, and destabilization is outlined to provide researchers and bilgewater treatment operators with the knowledge needed to determine emulsion prevention and treatment strategies. Furthermore, a broad assessment of bilgewater emulsion characterization techniques, from general water quality analysis to advanced droplet stability characterization methods are discussed in detail. Lastly, a survey of typical bilgewater characteristics and information on standard synthetic bilgewater mixtures used in the testing of oil pollution abatement equipment are presented. Overall, the goal of this article is to provide a better understanding of physical and thermodynamic properties of emulsions to help improve bilgewater treatment and management.
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Affiliation(s)
- Jared Church
- Wastewater Management Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, USA; Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, USA
| | - Jeffrey G Lundin
- Chemistry Division, United States Naval Research Laboratory, Washington, DC, USA
| | - Daniela Diaz
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, USA
| | - Dianne Mercado
- Burnette School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Marjorie R Willner
- Wastewater Management Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, USA
| | - Woo Hyoung Lee
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, USA
| | - Danielle M Paynter
- Wastewater Management Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, USA.
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15
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Kaganyuk M, Mohraz A. Impact of Particle Size on Droplet Coalescence in Solid-Stabilized High Internal Phase Emulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12807-12816. [PMID: 31484479 DOI: 10.1021/acs.langmuir.9b02223] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
High internal phase emulsions (HIPEs) comprise highly faceted droplets separated by thin films of fluid. Though surfactants are traditionally used in formulating HIPEs, growing interest in solid-stabilized HIPEs calls for a better understanding of how particles may affect the coalescence of droplets at high volume fractions of the dispersed phase. In this study, we address the effect of particle size on this issue. Using confocal microscopy, we examine the microstructures of four different solid-stabilized emulsion series and quantify droplet coalescence in each. We show that, systematically, HIPEs stabilized with smaller particles show a greater propensity for film rupture and the presence of partially coalesced droplets, whereas the use of larger particles results in a higher fraction of bridged particle monolayers between neighboring droplets. This result is in contrast with the behavior of dilute emulsions, where the use of smaller particles has been shown to impart greater stability against droplet coalescence. Utilizing a simple model of film rupture, we rationalize our experimental findings in the context of the capillary pressure profile within a solid-stabilized liquid film, and show that bridged monolayer formation is directly linked to improved film stability at high volume fractions of the dispersed phase. Therefore, particle size can impact the stability of solid-stabilized HIPEs by influencing their propensity for monolayer formation.
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Affiliation(s)
- Max Kaganyuk
- Department of Chemical and Biomolecular Engineering , University of California , Irvine , California 92697 , United States
| | - Ali Mohraz
- Department of Chemical and Biomolecular Engineering , University of California , Irvine , California 92697 , United States
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16
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Kunti G, Bhattacharya A, Chakraborty S. Strong rotating flow in stationary droplets in low power budget using wire electrode configuration. Electrophoresis 2019; 40:2971-2978. [PMID: 31424093 DOI: 10.1002/elps.201900272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/20/2019] [Accepted: 08/15/2019] [Indexed: 01/20/2023]
Affiliation(s)
- Golak Kunti
- Department of Mechanical EngineeringIndian Institute of Technology Kharagpur Kharagpur West Bengal India
| | - Anandaroop Bhattacharya
- Department of Mechanical EngineeringIndian Institute of Technology Kharagpur Kharagpur West Bengal India
| | - Suman Chakraborty
- Department of Mechanical EngineeringIndian Institute of Technology Kharagpur Kharagpur West Bengal India
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