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Ma Q, Lei Q, Liu F, Song Z, Khusid B, Zhang W. Evaluation of commercial nanofiltration and reverse osmosis membrane filtration to remove per-and polyfluoroalkyl substances (PFAS): Effects of transmembrane pressures and water matrices. Water Environ Res 2024; 96:e10983. [PMID: 38291820 DOI: 10.1002/wer.10983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 12/24/2023] [Accepted: 01/06/2024] [Indexed: 02/01/2024]
Abstract
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are now widely found in aquatic ecosystems, including sources of drinking water and portable water, due to their increasing prevalence. Among different PFAS treatment or separation technologies, nanofiltration (NF) and reverse osmosis (RO) both yield high rejection efficiencies (>95%) of diverse PFAS in water; however, both technologies are affected by many intrinsic and extrinsic factors. This study evaluated the rejection of PFAS of different carbon chain length (e.g., PFOA and PFBA) by two commercial RO and NF membranes under different operational conditions (e.g., applied pressure and initial PFAS concentration) and feed solution matrixes, such as pH (4-10), salinity (0- to 1000-mM NaCl), and organic matters (0-10 mM). We further performed principal component analysis (PCA) to demonstrate the interrelationships of molecular weight (213-499 g·mol-1 ), membrane characteristics (RO or NF), feed water matrices, and operational conditions on PFAS rejection. Our results confirmed that size exclusion is a primary mechanism of PFAS rejection by RO and NF, as well as the fact that electrostatic interactions are important when PFAS molecules have sizes less than the NF membrane pores. PRACTITIONER POINTS: Two commercial RO and NF membranes were both evaluated to remove 10 different PFAS. High transmembrane pressures facilitated permeate recovery and PFAS rejection by RO. Electrostatic repulsion and pore size exclusion are dominant rejection mechanisms for PFAS removal. pH, ionic strength, and organic matters affected PFAS rejection. Mechanisms of PFAS rejection with RO/NF membranes were explained by PCA analysis.
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Affiliation(s)
- Qingquan Ma
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Qian Lei
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Fangzhou Liu
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Zimu Song
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Boris Khusid
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Wen Zhang
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
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Lei Q, Elele E, Shen Y, Tang J, Guerra KL, Leitz F, Khusid B. Evaluating the Efficiency of Magnetic Treatment for Feed Water in Reverse Osmosis Processes. Membranes (Basel) 2023; 13:641. [PMID: 37505007 PMCID: PMC10383654 DOI: 10.3390/membranes13070641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/15/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023]
Abstract
The paper presents a new methodology for short-term (5-25 min) benchtop tests to evaluate the effectiveness of magnetic treatment of feed water for reducing mineral scaling on a reverse osmosis (RO) membrane. Scale deposition is measured at a controlled level of salt supersaturation in water flowing through an RO unit in once-through mode. A magnetic water conditioner is tested in a transient flow regime when variations of the permeate flux along the flow path are insignificant. Scale formation under these conditions is governed by salt crystallization on the membrane surface. The proposed method was implemented to investigate the influence of magnetic treatment on gypsum deposition on RO membranes in supersaturated aqueous CaSO4/NaCl solutions. The effects of magnetic water treatment on scale formation under our experimental conditions were found to be statistically insignificant with a confidence level of 95%. However, this outcome should not be considered to negate the potential efficiency of magnetic water treatment in specific applications. The proposed methodology of testing under a controlled level of salt supersaturation will also be useful for evaluating the efficiency of other water treatment technologies.
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Affiliation(s)
- Qian Lei
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
| | - Ezinwa Elele
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
| | - Yueyang Shen
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
| | - John Tang
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
| | - Katherine L Guerra
- Water Treatment Group, Technical Service Center, U.S. Bureau of Reclamation, P.O. Box 25007, Denver, CO 80225, USA
| | - Frank Leitz
- Water Treatment Group, Technical Service Center, U.S. Bureau of Reclamation, P.O. Box 25007, Denver, CO 80225, USA
| | - Boris Khusid
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
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Boymelgreen A, Schiffbauer J, Khusid B, Yossifon G. Synthetic electrically driven colloids: a platform for understanding collective behavior in soft matter. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lam MA, Khusid B, Kondic L, Meyer WV. Role of diffusion in crystallization of hard-sphere colloids. Phys Rev E 2021; 104:054607. [PMID: 34942784 DOI: 10.1103/physreve.104.054607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 10/12/2021] [Indexed: 11/07/2022]
Abstract
Vital for a variety of industries, colloids also serve as an excellent model to probe phase transitions at the individual particle level. Despite extensive studies, origins of the glass transition in hard-sphere colloids discovered about 30 y ago remain elusive. Results of our numerical simulations and asymptotic analysis suggest that cessation of long-time particle diffusivity does not suppress crystallization of a metastable liquid-phase hard-sphere colloid. Once a crystallite forms, its growth is then controlled by the particle diffusion in the depletion zone surrounding the crystallite. Using simulations, we evaluate the solid-liquid interface mobility from data on colloidal crystallization in terrestrial and microgravity experiments and demonstrate that there is no drastic difference between the respective mobility values. The insight into the effect of vanishing particle mobility and particle sedimentation on crystallization of colloids will help engineer colloidal materials with controllable structure.
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Affiliation(s)
- Michael A Lam
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Boris Khusid
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Lou Kondic
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - William V Meyer
- Universities Space Research Association at NASA Glenn Research Center, Cleveland, Ohio 44135, USA
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Damaraju SM, Shen Y, Elele E, Khusid B, Eshghinejad A, Li J, Jaffe M, Arinzeh TL. Three-dimensional piezoelectric fibrous scaffolds selectively promote mesenchymal stem cell differentiation. Biomaterials 2017; 149:51-62. [PMID: 28992510 DOI: 10.1016/j.biomaterials.2017.09.024] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/08/2017] [Accepted: 09/17/2017] [Indexed: 01/06/2023]
Abstract
The discovery of electric fields in biological tissues has led to efforts in developing technologies utilizing electrical stimulation for therapeutic applications. Native tissues, such as cartilage and bone, exhibit piezoelectric behavior, wherein electrical activity can be generated due to mechanical deformation. Yet, the use of piezoelectric materials have largely been unexplored as a potential strategy in tissue engineering, wherein a piezoelectric biomaterial acts as a scaffold to promote cell behavior and the formation of large tissues. Here we show, for the first time, that piezoelectric materials can be fabricated into flexible, three-dimensional fibrous scaffolds and can be used to stimulate human mesenchymal stem cell differentiation and corresponding extracellular matrix/tissue formation in physiological loading conditions. Piezoelectric scaffolds that exhibit low voltage output, or streaming potential, promoted chondrogenic differentiation and piezoelectric scaffolds with a high voltage output promoted osteogenic differentiation. Electromechanical stimulus promoted greater differentiation than mechanical loading alone. Results demonstrate the additive effect of electromechanical stimulus on stem cell differentiation, which is an important design consideration for tissue engineering scaffolds. Piezoelectric, smart materials are attractive as scaffolds for regenerative medicine strategies due to their inherent electrical properties without the need for external power sources for electrical stimulation.
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Affiliation(s)
- Sita M Damaraju
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
| | - Yueyang Shen
- Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
| | - Ezinwa Elele
- Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
| | - Boris Khusid
- Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
| | - Ahmad Eshghinejad
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Jiangyu Li
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA; Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Michael Jaffe
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
| | - Treena Livingston Arinzeh
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA.
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Yao N, Khusid B, Sirkar KK, Dehn DJ. Effects of Tri-n-octylamine with or without Diluents on Microporous Ethylene Chlorotrifluoroethylene Membranes. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b01839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Na Yao
- Otto
York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102, United States
| | - Boris Khusid
- Otto
York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102, United States
| | - Kamalesh K. Sirkar
- Otto
York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102, United States
| | - Derek J. Dehn
- 3M
Corporate Research Process Laboratory, 3M Center Building 219-1S-01, St.
Paul, Minnesota 55144, United States
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Yao N, Chau J, Elele E, Khusid B, Sirkar KK, Dehn DJ. Characterization of microporous ECTFE membrane after exposure to different liquid media and radiation. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Elele EO, Shen Y, Pettit DR, Khusid B. Detection of a dynamic cone-shaped meniscus on the surface of fluids in electric fields. Phys Rev Lett 2015; 114:054501. [PMID: 25699447 DOI: 10.1103/physrevlett.114.054501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Indexed: 06/04/2023]
Abstract
A cone-shaped meniscus of electrified fluids, often called a Taylor cone, is observed in rain drops and lightning and employed in various physical instruments and experimental techniques, but the way it evolves from a rounded shape to a cone is a long-standing puzzle. Earth's gravity and microgravity measurements on the meniscus whose height is just shy of droplet ejection reveal that field-driven cusp evolution exhibits a universal self-similarity insensitive to the forcing field and scaled by the fluid surface tension and density. Our work paves the way for dynamic control of field-driven phenomena in fluids.
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Affiliation(s)
- Ezinwa O Elele
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Yueyang Shen
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | | | - Boris Khusid
- New Jersey Institute of Technology, Newark, New Jersey 07102, USA
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Susarla R, Sievens-Figueroa L, Bhakay A, Shen Y, Jerez-Rozo JI, Engen W, Khusid B, Bilgili E, Romañach RJ, Morris KR, Michniak-Kohn B, Davé RN. Fast drying of biocompatible polymer films loaded with poorly water-soluble drug nano-particles via low temperature forced convection. Int J Pharm 2013; 455:93-103. [DOI: 10.1016/j.ijpharm.2013.07.051] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 06/29/2013] [Accepted: 07/19/2013] [Indexed: 10/26/2022]
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Abstract
The mechanisms leading to the deposition of colloidal particles in a copper-gold galvanic microreactor are investigated. Using in situ current density measurements and particle velocimetry, we establish correlations between the spatial arrangement and the geometry of the electrodes, current density distribution, and particle aggregation behavior. Ionic transport phenomena are responsible for the occurrence of strongly localized high current density at the edges and corners of the copper electrodes at large electrode separation, leading to a preferential aggregation of colloidal particles at the electrode edges. Preferential aggregation appears to be the result of a combination of electrophoretic effects and changes in bulk electrolyte flow patterns. We demonstrate that electrolyte flow is most likely driven by electrochemical potential gradients of reaction products formed during the inhomogeneous copper dissolution.
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Affiliation(s)
- Linda Jan
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Elele E, Shen Y, Susarla R, Khusid B, Keyvan G, Michniak-Kohn B. Electrodeless Electrohydrodynamic Drop-on-Demand Encapsulation of Drugs into Porous Polymer Films for Fabrication of Personalized Dosage Units. J Pharm Sci 2012; 101:2523-33. [DOI: 10.1002/jps.23165] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 03/26/2012] [Accepted: 04/04/2012] [Indexed: 11/11/2022]
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14
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Shen Y, Elele E, Khusid B. A novel concept of dielectrophoretic engine oil filter. Electrophoresis 2011; 32:2559-68. [DOI: 10.1002/elps.201100072] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/04/2011] [Accepted: 05/02/2011] [Indexed: 11/07/2022]
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Abstract
Molecular dynamics simulations are used to study dynamical coupling between conformational fluctuations of a highly charged flexible macromolecule and its surrounding ionic cloud. We find that the basic model of a polyelectrolyte as a chain of charged monomers captures the main experimental findings on the field-induced alignment of polyelectrolytes despite its simplicity. Contrary to current theories, the correlated local charge and field fluctuations in the vicinity of the macromolecule are found to dominate alignment along an external field. We suggest that short-lived monomer-counterion clustering can be probed by measuring the field-induced anisotropy of x-ray and neutron scattering from polymer solutions.
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Affiliation(s)
- Tak Shing Lo
- The Levich Institute and Department of Physics, City College of the City University of New York, New York, New York 10031, USA
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Murira CM, Punckt C, Schniepp HC, Khusid B, Aksay IA. Inhibition and promotion of copper corrosion by CTAB in a microreactor system. Langmuir 2008; 24:14269-75. [PMID: 19053648 DOI: 10.1021/la8024759] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report on an optical microscopy technique for the analysis of corrosion kinetics of metal thin films in microreactor systems and use it to study the role of cetyltrimethylammonium bromide surfactant as a corrosion inhibitor in a copper-gold galvanic coplanar microsystem. A minimum in the dissolution rate of copper is observed when the surfactant concentration is approximately 0.8 mM. To explain why the inhibitory role of the surfactant does not extend to higher concentrations, we use zero resistance ammetry with separated half cells and show that while the surfactant inhibits cathodic reactions on gold, it also promotes the corrosion of copper because of the catalytic action of bromide counterions. These two competing processes lead to the observed minimum in the dissolution rate.
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Affiliation(s)
- Caroline M Murira
- Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Abstract
Molecular dynamics simulations are used to study the spatiotemporal dynamics of charge fluctuations around a polyelectrolyte molecule at charge densities above and below the classic counterion condensation threshold. Surprisingly, the counterions form weakly interacting clusters which exhibit slowly decaying short range orientational order. Local charge fluctuations create energy fluctuations at the order of k_(B)T that is sufficient to affect the polyelectrolyte interaction with an approaching ligand molecule. The predictions of the classical theory appear to be appropriate only over much longer time scales.
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Affiliation(s)
- Tak Shing Lo
- Benjamin Levich Institute, City College of the City University of New York, New York, New York 10031, USA
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Kumar A, Khusid B, Acrivos A. Dielectrophoretic Trapping of Particles at the Three-Phase Contact Line. Ind Eng Chem Res 2006. [DOI: 10.1021/ie051151j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anil Kumar
- The Levich Institute, The City College of New York, 140th Street and Convent Avenue, New York, New York 10031, and New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102
| | - Boris Khusid
- The Levich Institute, The City College of New York, 140th Street and Convent Avenue, New York, New York 10031, and New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102
| | - Andreas Acrivos
- The Levich Institute, The City College of New York, 140th Street and Convent Avenue, New York, New York 10031, and New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102
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Abstract
We describe dielectric spectroscopy measurements on dispersions of two thermotropic liquid crystals (5CB and 8CB) in a poly(dimethylsiloxane) matrix. 5CB exhibits nematic and isotropic phases, while 8CB exhibits smectic, nematic, and isotropic phases. The spectra of the dispersions exhibit a temperature-dependent dielectric relaxation in the interval from 100 to 1000 Hz, with relaxation times that depend strongly on whether the dispersed phase is isotropic, nematic, or smectic. The dielectric relaxation times also depend on the viscosity of the matrix fluid. These results suggest a coupling between the electric field and the mechanics of the interface that affects the spectrum of the dispersed phase and shifts the Maxwell-Wagner interfacial polarization peak.
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Affiliation(s)
- Pradeep K Rai
- Benjamin Levich Institute for Physico-Chemical Hydrodynamics and Department of Chemical Engineering, City College of New York/CUNY, New York, New York 10031, USA
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Kumar A, Khusid B, Qiu Z, Acrivos A. New electric-field-driven mesoscale phase transitions in polarized suspensions. Phys Rev Lett 2005; 95:258301. [PMID: 16384516 DOI: 10.1103/physrevlett.95.258301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Indexed: 05/05/2023]
Abstract
We report the discovery of a new class of an electric field-driven bulk phase transition due solely to dipolar interactions in a suspension under the action of a uniform ac field where the effects of other competing forces are suppressed. This transition appears after the well-known chain-column formation and causes the uniform suspension of columns to rearrange into a cellular pattern consisting of particle-free domains surrounded by particle-rich walls. Interestingly, the characteristic size of these domains scales linearly with the interelectrode spacing and remains insensitive to the size of the particles.
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Affiliation(s)
- Anil Kumar
- The Levich Institute, The City College of New York, 140th Street & Convent Avenue, New York, New York 10031, USA
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Drazer G, Khusid B, Koplik J, Acrivos A. Hysteresis, force oscillations, and nonequilibrium effects in the adhesion of spherical nanoparticles to atomically smooth surfaces. Phys Rev Lett 2005; 95:016102. [PMID: 16090633 DOI: 10.1103/physrevlett.95.016102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Indexed: 05/03/2023]
Abstract
Equilibrium and nonequilibrium aspects of particle adsorption on the walls of fluid-filled nanochannels are examined via molecular dynamics simulations. The force on the particle and the free energy of the system are found to depend on the particle's history (hysteresis), in addition to its radial position and the wetting properties of the fluid, even when the particle moves quasistatically. The hysteresis is associated with changes in the fluid density in the gap between the particle and the wall, which persist over surprisingly long times. The force and free energy exhibit large oscillations with distance when the lattice of the structured nanoparticle is held in register with that of the tube wall, but not if the particle is allowed to rotate freely. Adsorbed particles are trapped in free-energy minima in equilibrium but can desorb if forced along the channel.
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Affiliation(s)
- German Drazer
- Benjamin Levich Institute, City College of the City University of New York, New York, New York 10031, USA.
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Kumar A, Qiu Z, Acrivos A, Khusid B, Jacqmin D. Combined negative dielectrophoresis and phase separation in nondilute suspensions subject to a high-gradient ac electric field. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 69:021402. [PMID: 14995439 DOI: 10.1103/physreve.69.021402] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Indexed: 05/24/2023]
Abstract
Experiments were conducted on concentrated suspensions of neutrally buoyant particles which exhibit negative dielectrophoresis. We found that, due to interparticle electrical interactions, such suspensions undergo a phase separation when subjected to a high-gradient ac field (approximately kV/mm) and form a propagating distinct front between the regions enriched with and depleted of particles. A generalization of our theory for the thermodynamics of the field-induced phase transitions in suspensions of polarized particles [Phys. Rev. E 52, 1669 (1995); 54, 5428 (1996); 60, 3015 (1999)] is proposed for the front propagation, and its predictions are shown to be consistent with the experiments even though the model contains no fitting parameters. The combination of field-induced dielectrophoresis and phase transition provides a method for strongly concentrating particles in prespecified regions of dielectrophoretic devices.
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Affiliation(s)
- Anil Kumar
- The Levich Institute, The City College of New York, 140th Street & Convent Avenue, New York, New York 10031, USA.
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Drazer G, Koplik J, Acrivos A, Khusid B. Adsorption phenomena in the transport of a colloidal particle through a nanochannel containing a partially wetting fluid. Phys Rev Lett 2002; 89:244501. [PMID: 12484949 DOI: 10.1103/physrevlett.89.244501] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2002] [Indexed: 05/24/2023]
Abstract
Using molecular dynamics simulations, we study the motion of a closely fitting nanometer-size solid sphere in a fluid-filled cylindrical nanochannel at low Reynolds numbers. At early times, when the particle is close to the middle of the tube, its velocity is in agreement with continuum calculations, despite large thermal fluctuations. At later times, partially wetting fluids exhibit novel adsorption phenomena: the sphere meanders away from the center of the tube and adsorbs onto the wall, and subsequently either sticks to the wall and remains motionless on average, or separates slightly from the tube wall and then either slips parallel to the mean flow or executes an intermittent stick-slip motion.
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Affiliation(s)
- German Drazer
- Benjamin Levich Institute and Department of Physics, City College of the City University of New York, New York 10031, USA.
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Khusid B, Acrivos A. Phase diagrams of electric-field-induced aggregation in conducting colloidal suspensions. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1999; 60:3015-35. [PMID: 11970110 DOI: 10.1103/physreve.60.3015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/1999] [Indexed: 04/18/2023]
Abstract
To develop a theory for electric-field-driven phase transitions in concentrated suspensions, we extended our microscopic theory [Phys. Rev. E 52, 1669, (1995); 54, 5428, (1996)] beyond the dilute regime. Based on the model of the Maxwell-Wagner interfacial polarization of colloids, our theory overcomes the limitations of Brillouin's formula for the electric energy of conducting materials which is applicable only for negligibly small energy dissipation and slow time variations of the field. We found that the phase diagrams of "the particle concentration vs the electric field strength" for colloids are similar to the phase diagrams for the first-order phase separation in quenched conventional binary systems with a high-temperature miscibility gap. This explains why a variety of colloids exhibit similar field-induced aggregation patterns. Our theory provides a reasonable interpretation of the available experimental data on field-induced aggregation phenomena in electrorheological fluids and aqueous suspensions, whereas currently used theoretical models are in variance with many of the data. The theoretical results enable one to trace how the variations of the electrical properties of the constituent materials influence the topology of the suspension phase diagram and to evaluate the effects of the field strength and frequency on the particle aggregation.
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Affiliation(s)
- B Khusid
- Department of Mechanical Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102, USA.
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Khusid B, Acrivos A. Effects of interparticle electric interactions on dielectrophoresis in colloidal suspensions. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1996; 54:5428-5435. [PMID: 9965728 DOI: 10.1103/physreve.54.5428] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Khusid B, Acrivos A. Effects of conductivity in electric-field-induced aggregation in electrorheological fluids. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 52:1669-1693. [PMID: 9963586 DOI: 10.1103/physreve.52.1669] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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