1
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Selection of suitable surfactants for the incorporation of organic liquids into fresh geopolymer pastes. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.117635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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2
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Stretch, fold, and break: Intensification of emulsification of high viscosity ratio systems by fractal mixers. AIChE J 2021. [DOI: 10.1002/aic.17192] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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3
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Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention. Catalysts 2020. [DOI: 10.3390/catal10020152] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Simultaneous generation of plasma by microwave irradiation of perovskite or the spinel type of silica supported porous catalyst oxides and their reduction by nitrogen in the presence of oxygen is demonstrated. As a result of plasma generation in air, NOx generation is accompanied by the development of highly heterogeneous regions in terms of chemical and morphological variations within the catalyst. Regions of almost completely reduced catalyst are dispersed within the catalyst oxide, across micron-scale domains. The quantification of the catalyst heterogeneity and evaluation of catalyst structure are studied using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and XRD. Plasma generating supported spinel catalysts are synthesized using the technique developed by the author (Catalysts; 2016; 6; 80) and BaTiO3 is used to exemplify perovskites. Silica supported catalyst systems are represented as M/Si = X (single catalysts) or as M(1)/M(2)/Si = X/Y/Z (binary catalysts) where M; M(1) M(2) = Cr; Mn; Fe; Co; Cu and X, Y, Z are the molar ratio of the catalysts and SiO2 support. Composite porous catalysts are synthesized using a mixture of Co and BaTiO3. In all the catalysts, structural heterogeneity manifests itself through defects, phase separation and increased porosity resulting in the creation of the high activity sites. The chemical heterogeneity results in reduced and oxidized domains and in very large changes in catalyst/support ratio. High electrical potential activity within BaTiO3 particles is observed through the formation of electrical treeing. Plasma generation starts as soon as the supported catalyst is synthesized. Two conditions for plasma generation are observed: Metal/Silica molar ratio should be > 1/2 and the resulting oxide should be spinel type; represented as MaOb (a = 3; b = 4 for single catalyst). Composite catalysts are represented as {M/Si = X}/BaTiO3 and obtained from the catalyst/silica precursor fluid with BaTiO3 particles which undergo fragmentation during microwave irradiation. Further irradiation causes plasma generation, NOx formation and lattice oxygen depletion. Partially reduced spinels are represented as MaOb–c. These reactions occur through a chemical looping process in micron-scale domains on the porous catalyst surface. Therefore; it is possible to scale-up this process to obtain NOx from MaOb for nitric acid production and H2 generation from MaOb–c by catalyst re-oxidized by water. Re-oxidation by CO2 delivers CO as fuel. These findings explain the mechanism of conversion of combustion gases (CO2 + N2) to CO and NOx via a chemical looping process. Mechanism of catalyst generation is proposed and the resulting structural inhomogeneity is characterized. Plasma generating catalysts also represent a new form of Radar Absorbing Material (RAM) for stealth and protection from radiation in which electromagnetic energy is dissipated by plasma generation and catalytic reactions. These catalytic RAMs can be expected to be more efficient in frequency independent microwave absorption.
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4
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Bidgoli MA, Hayaty M. Fabrication and characterization of nanoencapsulated epoxy resin/crosslinked PMMA shells with
in situ
polymerization via phase inversion emulsion (PIE) method. J Appl Polym Sci 2019. [DOI: 10.1002/app.48793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Mehran Hayaty
- Department of Applied ChemistryMalek‐Ashtar University of Technology 83145/115 Iran
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5
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Duan G, Kumar A, Li S, Cheng CM, Lee D. Effect of triblock copolymer surfactant composition on flow-induced phase inversion emulsification in a tapered channel. J Colloid Interface Sci 2019; 537:579-587. [PMID: 30471612 DOI: 10.1016/j.jcis.2018.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/06/2018] [Accepted: 11/07/2018] [Indexed: 11/15/2022]
Abstract
HYPOTHESIS Phase inversion emulsification (PIE) is a process that inverts the dispersed and continuous phases of an emulsion and is useful for preparing emulsions that are challenging to produce using conventional techniques. A recent work has shown that PIE can be induced by flowing an emulsion through a tapered channel. Although prior studies have shown that flow-induced PIE (FIPIE) is influenced by the flow conditions and wetting properties of the channel surface, little is known about the effect of surfactant structure on FIPIE. We hypothesize that FIPIE is affected by the composition and structure of the surfactant used for emulsion stabilization. EXPERIMENTS We use Pluronics, a series of ABA triblock copolymers composed of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO) with various lengths (A = PEO, B = PPO), as model surfactants to test this hypothesis. We observe that triblock copolymer surfactants with long PEO blocks suppress FIPIE. A scaling analysis based on a polymer brush model qualitatively agrees with the experimental observation. We also show that for small molecular weight Pluronics, FIPIE is significantly suppressed when Pluronics with large PPO blocks are used. FINDINGS Our results strongly indicate that the steric repulsion provided by the PEO blocks as well as the dilatational elasticity provided by the PPO blocks are key factors that control the FIPIE process.
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Affiliation(s)
- Gang Duan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Ankit Kumar
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Shigeng Li
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, NY 14580, United States
| | - Chieh-Min Cheng
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, NY 14580, United States
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States.
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6
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Catté M, Ontiveros JF, Aramaki K, Pierlot C. Catastrophic Emulsion Inversion Process of Highly Viscous Isosorbide Biobased Polyester Monitoredin situ by Torque and Light Backscattering. J Oleo Sci 2018; 67:925-931. [PMID: 30068827 DOI: 10.5650/jos.ess18057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Highly viscous hydrophobic isosorbide biobased polyester O/W emulsions are prepared through catastrophic phase inversion. The process is followed in situ with two different methods: torque and light backscattering (LBS). Considering high viscosity of the system, only discontinuous conductivity monitoring is performed for comparison. Torque and LBS allow to highlight the emulsion inversion point (EIP) with relatively close water weight fraction values (fw≈0.20). The torque and LBS signals are rather noisy before inversion (evolution of different structures) and more smooth after phase inversion (continuous aqueous phase). Torque gives a more macroscopic information, representative of the global state of the dispersion. Consistent conductivity and torque measurements suggest indeed an inversion pathway through multiple o/W/O emulsions leading to multiple complex structures before getting continuous aqueous final emulsion. This hypothesis is confirmed with continuous LBS monitoring and microscopic observations. LBS signal seems more complete because it combines the information of conductivity and torque and allows to clearly follow in situ the inversion from the beginning to the end of the process.
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Affiliation(s)
- Marianne Catté
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide
| | - Jesús F Ontiveros
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide
| | - Kenji Aramaki
- Graduate School of Environment and Information Sciences, Yokohama National University
| | - Christel Pierlot
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide
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7
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Goger A, Thompson MR, Pawlak JL, Arnould MA, Lawton DJW. Solvent-free polymer emulsification inside a twin-screw extruder. AIChE J 2018. [DOI: 10.1002/aic.16066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ali Goger
- Dept. of Chemical Engineering; McMaster University; Hamilton ON Canada L8S 4L7
| | - Michael R. Thompson
- Dept. of Chemical Engineering; McMaster University; Hamilton ON Canada L8S 4L7
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8
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Pierlot C, Ontiveros JF, Royer M, Catté M, Salager JL. Emulsification of viscous alkyd resin by catastrophic phase inversion with nonionic surfactant. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.07.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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Goger A, Thompson MR, Pawlak JL, Arnould MA, Klymachyov A, Lawton DJW. Effect of Viscosity on Solvent-Free Extrusion Emulsification: Molecular Structure. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b03370] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Goger
- Department of Chemical
Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - M. R. Thompson
- Department of Chemical
Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - J. L. Pawlak
- Xerox Corporation, Rochester, New York, United States
| | - M. A. Arnould
- Xerox Corporation, Rochester, New York, United States
| | - A. Klymachyov
- Xerox Corporation, Rochester, New York, United States
| | - D. J. W. Lawton
- Xerox Research Center of Canada, Mississauga, Ontario L5K
2L1, Canada
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10
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Goger A, Thompson M, Pawlak J, Arnould M, Klymachyov A, Sheppard R, Lawton D. Inline rheological behavior of dispersed water in a polyester matrix with a twin screw extruder. POLYM ENG SCI 2017. [DOI: 10.1002/pen.24613] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A. Goger
- Department of Chemical Engineering; McMaster University; Hamilton Ontario Canada
| | - M.R. Thompson
- Department of Chemical Engineering; McMaster University; Hamilton Ontario Canada
| | | | | | | | | | - D.J.W. Lawton
- Xerox Research Center of Canada; Mississauga Ontario Canada
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11
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Kumar A, Li S, Cheng CM, Lee D. Flow-induced phase inversion of emulsions in tapered microchannels. LAB ON A CHIP 2016; 16:4173-4180. [PMID: 27714000 DOI: 10.1039/c6lc01060a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Phase inversion emulsification (PIE) is a process of generating emulsions by inverting the continuous and dispersed phases of pre-existing emulsions. Although PIE is conventionally performed in batch processes, flowing emulsions through precisely engineered channels (i.e. flow-induced phase inversion emulsification (FIPIE)) can induce PIE and potentially enable continuous processing. In this study, we demonstrate flow-induced phase inversion of oil-in-water (O/W) emulsions using microfluidic channels with gradual constriction. We investigate the importance of wetting properties and geometric characteristics of microfluidic channels on FIPIE. We show that two dimensionless groups, Ca and the ratio of droplet-size to channel dimensions determine the outcome of the process. In situ observation of individual droplets undergoing FIPIE reveals that the rupture of films of the continuous (water) phase between oil droplets and a wetting oil layer on the surface of microchannels is the most crucial step for phase inversion. Finally, we compare our experimental observations with a scaling relationship that is based on the force balance between disjoining pressure and Laplace pressure, which provides insights into the underlying physical phenomena responsible for the rupture of the aqueous film and the occurrence of FIPIE. We believe our work provides critical insights and parameters for designing channels and pores that can be used for continuous PIE.
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Affiliation(s)
- Ankit Kumar
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | - Shigeng Li
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, New York 14580, USA
| | - Chieh-Min Cheng
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, New York 14580, USA
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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12
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Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors. Catalysts 2016. [DOI: 10.3390/catal6060080] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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13
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Phase Inversion Emulsification and Enhancement of Physical Properties for Cationic Emulsified Asphalt. ELASTOMERS AND COMPOSITES 2015. [DOI: 10.7473/ec.2015.50.4.265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Affiliation(s)
- Ankit Kumar
- Department
of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Shigeng Li
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, New York 14580, United States
| | - Chieh-Min Cheng
- Manufacturing & Materials Technology Area, Toner Development & Manufacturing Group, Xerox Corporation, Webster, New York 14580, United States
| | - Daeyeon Lee
- Department
of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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15
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Barlık N, Keskinler B, Kocakerim MM, Akay G. Surface modification of monolithic PolyHIPE Polymers for anionic functionality and their ion exchange behavior. J Appl Polym Sci 2015. [DOI: 10.1002/app.42286] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Necla Barlık
- Department of Environmental Engineering; Engineering Faculty; Atatürk University; 25100 Erzurum Turkey
| | - Bülent Keskinler
- Department of Environmental Engineering; Gebze Institute of Technology; 41400 Kocaeli Turkey
| | - M. Muhtar Kocakerim
- Department of Chemical Engineering; Engineering Faculty; Çankırı Karatekin University; 18000 Çankırı Turkey
| | - Galip Akay
- GAP Technologies; 1 Grosvenor Place, 8th Floor London SW1X 7HJ United Kingdom
- School of Chemical Engineering and Advanced Materials; Newcastle University; Newcastle upon Tyne NE1 7RU UK
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16
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17
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Ozoner SK, Keskinler B, Erhan E. HRP immobilized microporous Poly(styrene-divinylbenzene-polyglutaraldehyde) monolith for forced flow injected phenol biosensing. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2011. [DOI: 10.1016/j.msec.2010.12.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Akay G, Dissanayake B, Morgan A. Process Intensification in Particle Technology: Production of Powder Coatings by Nonisothermal Flow-Induced Phase Inversion. Ind Eng Chem Res 2011. [DOI: 10.1021/ie101516r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Galip Akay
- School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K
| | - Bandara Dissanayake
- School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K
| | - Andy Morgan
- AkzoNobel Powder Coatings Ltd., Stoneygate Lane, Felling, Gateshead, NE10 0JY, U.K
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19
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Burke DR, Akay G, Bilsborrow PE. Development of novel polymeric materials for agroprocess intensification. J Appl Polym Sci 2010. [DOI: 10.1002/app.32640] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Rameshwaram J, Yang YS, Jeon H. Structure–property relationships of nanocomposite-like polymer blends with ultrahigh viscosity ratios. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.05.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Vladisavljević GT, Williams RA. Recent developments in manufacturing emulsions and particulate products using membranes. Adv Colloid Interface Sci 2005; 113:1-20. [PMID: 15763236 DOI: 10.1016/j.cis.2004.10.002] [Citation(s) in RCA: 218] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Accepted: 10/15/2004] [Indexed: 10/26/2022]
Abstract
Membrane emulsification (ME) is a relatively new technique for the highly controlled production of particulates. This review focuses on the recent developments in this area, ranging from the production of simple oil-in-water (O/W) or water-in-oil (W/O) emulsions to multiple emulsions of different types, solid-in-oil-in-water (S/O/W) dispersions, coherent solids (silica particles, solid lipid microspheres, solder metal powder) and structured solids (solid lipid microcarriers, gel microbeads, polymeric microspheres, core-shell microcapsules and hollow polymeric microparticles). Other emerging technologies that extend the capabilities into different membrane materials and operation methods (such as rotating membranes, repeated membrane extrusion of coarsely pre-emulsified feeds) are introduced. The results of experimental work carried out by cited researchers in the field together with those of the current authors are presented in a tabular form in a rigorous and systematic manner. These demonstrate a wide range of products that can be manufactured using different membrane approaches. Opportunities for creation of new and novel entities are highlighted for low throughput applications (medical diagnostics, healthcare) and for large-scale productions (consumer and personal products).
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Affiliation(s)
- Goran T Vladisavljević
- Institute of Food Technology and Biochemistry, Faculty of Agriculture, University of Belgrade, P.O. Box 127, YU-11081 Belgrade-Zemun, Serbia & Montenegro.
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22
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Akay G, Erhan E, Keskinler B. Bioprocess intensification in flow-through monolithic microbioreactors with immobilized bacteria. Biotechnol Bioeng 2005; 90:180-90. [PMID: 15742387 DOI: 10.1002/bit.20376] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microporous polymers (with porosity up to 90%) with a well-prescribed internal microstructure were prepared in monolithic form to construct a flow-through microbioreactor in which phenol-degrading bacteria, Pseudomonas syringae, was immobilized. Initially, bacteria was forced seeded within the pores and subsequently allowed to proliferate followed by acclimatization and phenol degradation at various initial substrate concentrations and flow rates. Two types of microporous polymer were used as the monolithic support. These polymers differ with respect to their pore and interconnect sizes, macroscopic surface area for bacterial support, and phase volume. Polymer with a nominal pore size of 100 microm with phase volume of 90% (with highly open pore structure) yielded reduced bacterial proliferation, while the polymer with nominal pore size of 25 microm with phase volume of 85% (with small interconnect size and large pore area for bacterial adhesion) yielded monolayer bacterial proliferation. Bacteria within the 25 microm polymer support remained monolayered, without any apparent production of extracellular matrix during the 30-day continuous experimental period. The microbioreactor performance was characterized in terms of volumetric utilization rate and compared with the published data, including the case where the same bacteria was immobilized on the surface of microporous polymer beads and used in a packed bed during continuous degradation of phenol. It is shown that at similar initial substrate concentration, the volumetric utilization in the microreactor is at least 20-fold more efficient than the packed bed, depending on the flow rate of the substrate solution. The concentration of the bacteria within the pores of the microreactor decreases from 2.25 cells per microm2 on the top surface to about 0.4 cells per microm2 within 3 mm reactor depth. If the bacteria-depleted part of the microreactor is disregarded, the volumetric utilization increases by a factor of 30-fold compared with the packed bed. This efficiency increase is attributed to the reduction of diffusion path for the substrate and nutrients and enhanced availability of the bacteria for bioconversion in the absence of biofilm formation as well as the presence of flow over the surface of the monolayer bacteria.
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Affiliation(s)
- G Akay
- Process Intensification and Miniaturization Centre, School of Chemical Engineering and Advanced Materials, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom.
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23
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Saw LK, Brooks BW, Carpenter KJ, Keight DV. Catastrophic phase inversion in region II of an ionomeric polymer–water system. J Colloid Interface Sci 2004; 279:235-43. [PMID: 15380434 DOI: 10.1016/j.jcis.2004.06.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2003] [Accepted: 06/17/2004] [Indexed: 11/24/2022]
Abstract
Previous work has identified distinct regions, on a phase inversion map, for dispersions of polyurethane ionomer (PUI) and water. In this study, events that occur, before, during, and after catastrophic phase inversion (provoked by adding water to polyurethane ionomer (PUI) in the RII regions of the phase inversion map) have been studied in order to characterise the inversion mechanism. Before phase inversion, initial water addition leads to the hydration of ionic groups and eventually water drops start to form in the hydrophobic portions of the polymer matrix. At the phase inversion point, the PUI-water interface restructures and the ionomer disintegrates into a dispersion of spherical particles enclosed by a continuous aqueous phase. It is suggested that pseudo-drop structures are formed simultaneously during the production of the small polymer-in-water drops. After phase inversion, water addition dilutes the emulsion and destroys the apparent ionic-centre-rich environment surrounding any isolated ionic groups on a particle surface. The larger water-in-polymer drops are likely to have participated in the phase inversion and the smaller water drops form the primary water drops in the multiple emulsions. The resultant emulsions are stable over a period of a few months but very few multiple drops remain after 1(1/4) years.
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Affiliation(s)
- L K Saw
- Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK
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24
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Uriguen JI, Bremer L, Mathot V, Groeninckx G. Preparation of water-borne dispersions of polyolefins: new systems for the study of homogeneous nucleation of polymers. POLYMER 2004. [DOI: 10.1016/j.polymer.2004.06.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Akay G, Birch MA, Bokhari MA. Microcellular polyHIPE polymer supports osteoblast growth and bone formation in vitro. Biomaterials 2004; 25:3991-4000. [PMID: 15046889 DOI: 10.1016/j.biomaterials.2003.10.086] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2003] [Accepted: 10/10/2003] [Indexed: 10/26/2022]
Abstract
A novel micro-cellular polymer with a well-defined and uniform micro-architecture has been developed as a three-dimensional support matrix for in vitro tissue engineering applications. This material is manufactured through a high internal phase emulsion (HIPE) polymerization route and may be modified with hydroxyapatite. The generic form of the support is known as PolyHIPE Polymer (PHP). By changing the chemical composition of the emulsion and the processing conditions, the pore size can be altered from sub-micron range to a few hundred microns and the porosity varied from 70% to 97%. Our work has investigated the use of this micro-porous polymer as a biomaterial to support the growth of osteoblasts, the bone forming cells in vitro. Three groups of polymers were used that had pore sizes of 40, 60 and 100 microm. Results demonstrated in vitro cell-polymer compatibility, with osteoblasts forming multicellular layers on the polymer surface and also migrating to a maximum depth of 1.4mm inside the scaffold after 35 days in culture. PHP was also able to support the differentiation of osteoblasts and the production of a bone-like matrix. The effect of modifying the polymer with hydroxyapatite was also studied and showed that there was a significant increase in osteoblast numbers penetrating into the polymer. There were few differences, between the pore sizes studied, on the overall penetration of osteoblasts into the polymer but the rate of movement into 100 microm PHP was significantly higher compared to the other sizes investigated. This study shows that osteoblasts seeded onto PHP demonstrate cellular attachment, proliferation and ingrowth leading to the support of an osteoblastic phenotype. Therefore this highly porous scaffold has a potential for bone tissue engineering.
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Affiliation(s)
- G Akay
- Institute for Nanoscale Science and Technology, and Process Intensification and Miniaturisation Centre, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.
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26
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Thakur R, Vial C, Nigam K, Nauman E, Djelveh G. Static Mixers in the Process Industries—A Review. Chem Eng Res Des 2003. [DOI: 10.1205/026387603322302968] [Citation(s) in RCA: 352] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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27
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Pekdemir T, Akay G, Dogru M, Merrells RE, Schleicher B. Demulsification of Highly Stable Water-in-Oil Emulsions. SEP SCI TECHNOL 2003. [DOI: 10.1081/ss-120018129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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28
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Saw LK, Brooks BW, Carpenter KJ, Keight DV. Different dispersion regions during the phase inversion of an ionomeric polymer–water system. J Colloid Interface Sci 2003; 257:163-72. [PMID: 16256468 DOI: 10.1016/s0021-9797(02)00030-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2001] [Accepted: 09/18/2002] [Indexed: 10/27/2022]
Abstract
Catastrophic phase inversion is induced by changing the phase ratio in a liquid-liquid dispersion and is widely used during the dispersion stage in the production of aqueous polyurethane ionomer (PUI) colloids. In the work reported here, water was added to polyurethane ionomer prepolymer (PUIp) until the water became the continuous phase. Three different dispersion regions have been discovered by changing the ionic group content. Stable emulsions containing small polymer drops were produced in Region I. Stable coarse emulsions containing a mixture of drop structures were produced in Region II, but only temporary dispersions could be produced in Region III. Conductivity measurements could not always be used to detect the phase inversion points effectively because the PUIp was swollen by water. Therefore, torque change measurements have been used in conjunction with the conductivity measurements to detect the phase inversion points for all three dispersion regions. Scanning electron microscopy (SEM) and optical microscopy were used to obtain images of these dispersions in the different regions. A catastrophic phase inversion map is used to represent the changes that occur in the PUIp-W dispersions. This map is plotted using the ionic group content as the ordinate and water content (at the phase inversion points) as the abscissa.
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Affiliation(s)
- L K Saw
- Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
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Akay G, Tong L, Addleman R. Process Intensification in Particle Technology: Intensive Granulation of Powders by Thermomechanically Induced Melt Fracture. Ind Eng Chem Res 2002. [DOI: 10.1021/ie0201213] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. Akay
- Process Intensification and Miniaturisation Centre, School of Chemical Engineering and Advanced Materials, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom, and Rosand Precision Ltd., 19 Oakland Rise, Welwyn AL6 0RN, United Kingdom
| | - L. Tong
- Process Intensification and Miniaturisation Centre, School of Chemical Engineering and Advanced Materials, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom, and Rosand Precision Ltd., 19 Oakland Rise, Welwyn AL6 0RN, United Kingdom
| | - R. Addleman
- Process Intensification and Miniaturisation Centre, School of Chemical Engineering and Advanced Materials, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom, and Rosand Precision Ltd., 19 Oakland Rise, Welwyn AL6 0RN, United Kingdom
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Erhan E, Keskinler B, Akay G, Algur O. Removal of phenol from water by membrane-immobilized enzymes. J Memb Sci 2002. [DOI: 10.1016/s0376-7388(01)00779-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Akay G, Tong L. Preparation of Colloidal Low-Density Polyethylene Latexes by Flow-Induced Phase Inversion Emulsification of Polymer Melt in Water. J Colloid Interface Sci 2001; 239:342-357. [PMID: 11426998 DOI: 10.1006/jcis.2001.7615] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study is to prepare colloidal polymeric latexes by using the flow-induced phase inversion emulsification method given by G. Akay [Chem. Eng. Sci. 53, 203 (1998)] of polymer melts followed by the solidification of polymer melt droplets. We also investigate the mechanism of emulsification and stabilization in polymeric dispersions which undergo a phase change after emulsification. The history of the emulsification and emulsion structure are monitored by using a process rheometer and off-line scanning electron microscopy with energy-dispersive X-ray analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and particle size measurements. It is shown that the molecular structure of the surface-active material is the most important parameter in achieving phase inversion emulsificationin polymer melts. Molecular surfactants could not be used to provide surface activity in polymeric melts. Several experimental polymeric surfactants are used and their ability to form a [water-in-polymer melt] emulsion is tested. The successful polymeric surfactants are known as hydrophobically modified water-soluble polymers. It is postulated that the surface-active materials should conform at the water/polymer melt interface and not be removed from the interface by surface deformations. The ability of hydrophobically modified water-soluble polymers to remain at the interface is reduced if the hydrophobic moeties which anchor into the polymer melt have chain length approaching 18 carbons or more. After the first phase inversion and subsequent dilution of the [polymer melt-in-water], if mixing is carried out while cooling, a second phase inversion takes place from [polymer melt-in-water] to [water-in-solid polymer] despite high water content of the polymer/water system. If the water content is high (25-40% investigated) the second phase inversion yields a powdered material with encapsulated water. A third phase inversion occurs if the powdered microcapsules from the second phase inversion is heated while mixing to yield a [(water-in-polymer)-in-water] multiple emulsion which can be inverted back to [polymer melt-in-water] emulsion by increasing the temperature and subjecting the emulsion to high deformation rate flows. However, if this last phase inversion is not allowed to proceed to completion, and the [(water-in-polymer)-in-water] multiple emulsion is cooled, microporous polymeric particles are obtained. Copyright 2001 Academic Press.
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Affiliation(s)
- G. Akay
- Centre for Process Intensification and Innovation, Department of Chemical and Process Engineering, University of Newcastle, Newcastle upon Tyne, NE1 7RU, United Kingdom
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Bulut S, Waites WM, Mitchell JR. Effects of combined shear and thermal forces on destruction of Microbacterium lacticum. Appl Environ Microbiol 1999; 65:4464-9. [PMID: 10508076 PMCID: PMC91594 DOI: 10.1128/aem.65.10.4464-4469.1999] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A twin-screw extruder and a rotational rheometer were used to generate shear forces in concentrated gelatin inoculated with a heat-resistant isolate of a vegetative bacterial species, Microbacterium lacticum. Shear forces in the extruder were mainly controlled by varying the water feed rate. The water content of the extrudates changed between 19 and 45% (wet weight basis). Higher shear forces generated at low water contents and the calculated die wall shear stress correlated strongly with bacterial destruction. No surviving microorganisms could be detected at the highest wall shear stress of 409 kPa, giving log reduction of 5.3 (minimum detection level, 2 x 10(4) CFU/sample). The mean residence time of the microorganism in the extruder was 49 to 58 s, and the maximum temperature measured in the end of the die was 73 degrees C. The D(75 degrees C) of the microorganism in gelatin at 65% water content was 20 min. It is concluded that the physical forces generated in the reverse screw element and the extruder die rather than heat played a major part in cell destruction. In a rotational rheometer, after shearing of a mix of microorganisms with gelatin at 65% (wt/wt) moisture content for 4 min at a shear stress of 2.8 kPa and a temperature of 75 degrees C, the number of surviving microorganisms in the sheared sample was 5.2 x 10(6) CFU/g of sample compared with 1.4 x 10(8) CFU/g of sample in the nonsheared control. The relative effectiveness of physical forces in the killing of bacteria and destruction of starch granules is discussed.
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Affiliation(s)
- S Bulut
- Division of Food Sciences, School of Biological Sciences, University of Nottingham, Sutton Bonington Campus, Nr. Loughborough, Leicestershire LE12 5RD, England, United Kingdom.
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