2024 |
Ireland PM, 'Modelling dense particle streams during free-fall electrostatic separation', Powder Technology, 434 (2024) [C1]
Electrostatic particle separation is an attractive option for dry processing in the resource and recycling industries. Free-fall electrostatic separators are particularly simple a... [more]
Electrostatic particle separation is an attractive option for dry processing in the resource and recycling industries. Free-fall electrostatic separators are particularly simple and versatile member of this family of technologies. This paper presents numerical simulations of the movement of particles with different charges and masses within a stream of other particles in an electric field. The modelled system comprises much larger numbers and higher spatial densities of particles than previous models, and allows a realistic assessment of the effect of interparticle electrostatic forces and collisions. The effect of an angled feed with both co- and counter-directional fields is investigated, and the results translated to grade-recovery curves for different configurations. Among the important results were the degradation of separation performance with particle feed rate, the potential importance of Coulombic interparticle reactions in dense particle streams, and the benefits of an angled feed with a counter-directional electric field.
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Nova |
2023 |
Takeuchi K, Ireland PM, Webber GB, Wanless EJ, Hayashi M, Sakabe R, Fujii S, 'Electrostatic Adsorption Behaviors of Polymer Plates to a Droplet.', Langmuir, 39 9617-9626 (2023) [C1]
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Nova |
2022 |
Lobel BT, Robertson H, Webber GB, Ireland PM, Wanless EJ, 'Impact of surface free energy on electrostatic extraction of particles from a bed', Journal of Colloid and Interface Science, 611 617-628 (2022) [C1]
Hypothesis: Electrostatic extraction of particles from a bed to a pendent droplet to form liquid marbles has previously been investigated with respect to particle conductivity, si... [more]
Hypothesis: Electrostatic extraction of particles from a bed to a pendent droplet to form liquid marbles has previously been investigated with respect to particle conductivity, size and shape, however, interparticle forces have not been specifically interrogated. If cohesion is the dominant force within the particle bed, then particles will be more readily extracted with reduced surface free energy. Experiments: Glass particles were surface-modified using various alkyltrichlorosilanes. The surface free energy was measured for each sample using colloid probe atomic force microscopy (AFM) and sessile drop measurements on similarly modified glass slides. The ease of electrostatic particle extraction of each particle sample to a pendent droplet was compared by quantifying the electric field force required for successful extraction as a function of the measured surface free energy. Findings: Surface free energy calculated from sessile droplet measurements and AFM were not in agreement, as work of adhesion of a liquid droplet on a planar substrate is not representative of the contact between particles. Ease of electrostatic extraction of particles was observed to generally decrease as a function of AFM-derived surface free energy, confirming this is a critical factor in electrostatic delivery of particles to a pendent droplet. Roughness was also shown to inhibit particle extraction.
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Nova |
2022 |
Lobel BT, Hobson MJ, Ireland PM, Webber GB, Thomas CA, Ogino H, et al., 'Interparticle Repulsion of Microparticles Delivered to a Pendent Drop by an Electric Field', Langmuir, 38 670-679 (2022) [C1]
We report an unusually large spacing observed between microparticles after delivery to the surface of a pendent water droplet using a DC nonuniform electrostatic field, primarily ... [more]
We report an unusually large spacing observed between microparticles after delivery to the surface of a pendent water droplet using a DC nonuniform electrostatic field, primarily via dielectrophoresis. The influence of particle properties was investigated using core particles, which were either coated or surface-modified to alter their wettability and conductivity. Particles that exhibited this spacing were both hydrophobic and possessed some dielectric material exposed to the external field, such as a coating or exposed dielectric core. The origin of this behavior is proposed to be the induced dipole-dipole repulsion between particles, which increases with particle size and decreases when the magnitude of the electric field is reduced. When the particles were no longer subjected to an external field, this large interparticle repulsion ceased and the particles settled to the bottom of the droplet under the force of gravity. We derive a simple model to predict this spacing, with the dipole-dipole repulsion balanced against particle weight. The external electric field was calculated using the existing electric field models. The spacing was found to be dependent on particle density and the induced dipole moment as well as the number of particles present on the droplet interface. As the number of particles increased, a decrease in interparticle spacing was observed.
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Nova |
2021 |
Lobel BT, Thomas CA, Ireland PM, Wanless EJ, Webber GB, 'Liquid marbles, formation and locomotion using external fields and forces', Advanced Powder Technology, 32 1823-1832 (2021) [C1]
Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may ... [more]
Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may range from nanometre to millimetre if handled with sufficient care. This method, however, runs the risk of droplet coalescence and is limited to non-wetting particles. Currently there exist some alternative methods of formulation including using electrostatics to either deliver a particle bed to the droplet or pull the droplet to the particles. The former has shown some promise in potential batch processes but is hindered by interparticle forces. Additional production methods include a form of blender, but this has shown to be unable to produce marbles of a narrow size distribution. Once formed, liquid marbles have demonstrated value as potential blood typing devices, as micro-reaction vessels due to the inherent barrier between the internal phase and the substrate whilst maintaining gas permeability, and as contaminant sensors. Liquid marbles also demonstrate a remarkable level of elasticity under compressive force and reduced evaporation rates when compared to bare water droplets, a function of the size and composition of the stabilising particles. In addition to this, liquid marbles have been proposed as actuators. Locomotion may easily be induced in these structures, using electrostatics, sound, magnetism or light depending on the particle/liquid combinations used in formation, and the environment of deployment. This review seeks to present and summarise recent advances in the field of liquid marble manufacture and methods for actuation. We also aim to highlight potential future avenues of further study within this arena.
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Nova |
2020 |
Lobel BT, Ireland PM, Walsh LM, Thomas CA, Webber GB, Wanless EJ, 'Electrostatic Transfer of Conductive Particles for the Formation of Liquid Marbles-Charge Transfer Behavior', Journal of Physical Chemistry C, 124 9947-9957 (2020) [C1]
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Nova |
2020 |
Lobel BT, Fujiwara J, Fujii S, Thomas CA, Ireland PM, Wanless EJ, Webber GB, 'Formation of liquid marbles & aggregates: rolling and electrostatic formation using conductive hexagonal plates', Materials Advances, 1 3302-3313 [C1]
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Nova |
2020 |
Thomas CA, Munday H, Lobel BT, Asaumi Y, Fujii S, Ireland PM, et al., 'Exploring the Impact of Particle Material Properties on Electrostatic Liquid Marble Formation', Journal of Physical Chemistry C, 124 26258-26267 (2020) [C1]
Specific particle material properties such as conductivity, cohesion, and density have been neither directly nor thoroughly studied regarding particle behavior in an electrostatic... [more]
Specific particle material properties such as conductivity, cohesion, and density have been neither directly nor thoroughly studied regarding particle behavior in an electrostatic field and the follow-on impact this has on the electrostatic formation of liquid marbles. In this method, an applied electric field drives the extraction of particles from a bed and their transport to a pendent, earthed water droplet. Herein, prior studies of electrostatic formation of particle-stabilized droplets and liquid marbles have been expanded to compare the impact of density using the spherical polystyrene (PS) latex and glass particles of similar shape and size. The addition of thin polymer shells to both samples, which increases the conductivity and cohesion, allows the interplay of these three properties to be examined systematically. Separation distances between the particle bed and the droplet from which particles can initially be extracted increase as the negative applied potential increases. Initial extraction distances of both core particles were found to be similar, ~1.5 mm at 2.0 kV applied potential, despite the greater density, and thus mass of the glass particles. It is demonstrated that this is a result of competitive interactions between particle density, conductivity, and cohesion; PS is less conductive and more cohesive than glass. Introducing a polypyrrole shell increases the separation distance for extraction to approximately 4 mm for PS core particles but has little impact on glass core particles, demonstrating that for particles with constant conductivity and cohesion reducing the density facilitates extraction. Modeling and quantification of extraction threshold forces for each particle type were undertaken, utilizing the measurement of a radially symmetric area of the particle bed from which particles were observed in the initial extraction stages. This measurement highlighted that it is significantly easier to extract PS compared to glass, with particles extracted from a region in the bed up to 5 times the width in the PS case. Particle density is hypothesized to not be the determining factor in the stabilization of the coated liquid droplets; therefore, the interplay of a multitude of physical properties must be considered when determining the suitability of particulate materials for this electrostatic method.
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Nova |
2020 |
Baynham S, Ireland P, Galvin K, 'Enhancing Ion Flotation through Decoupling the Overflow Gas and Liquid Fluxes', MINERALS, 10 (2020) [C1]
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Nova |
2019 |
Ireland PM, 'Impact tribocharging of soft elastic spheres', Powder Technology, 348 70-79 (2019) [C1]
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Nova |
2019 |
Ireland PM, Neville F, Dickinson JE, Galvin KP, 'Enhancing extraction in ion flotation using the boycott effect', Chemical Engineering and Processing - Process Intensification, 145 (2019) [C1]
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Nova |
2019 |
Thomas CA, Kasahara M, Asaumi Y, Lobel BT, Fujii S, Ireland PM, et al., 'Influence of particle size on extraction from a charged bed - toward liquid marble formation', SOFT MATTER, 15 7547-7556 (2019) [C1]
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Nova |
2019 |
Kawata Y, Thomas CA, Asaumi Y, Hanochi H, Ireland PM, Fujii S, et al., 'Electrostatic Formation of Liquid Marbles Using Thermo-responsive Polymer-coated Particles', CHEMISTRY LETTERS, 48 578-581 (2019) [C1]
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Nova |
2018 |
Kido K, Ireland PM, Sekido T, Wanless EJ, Webber GB, Nakamura Y, Fujii S, 'Formation of Liquid Marbles Using pH-Responsive Particles: Rolling vs Electrostatic Methods', LANGMUIR, 34 4970-4979 (2018) [C1]
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Nova |
2018 |
Ireland PM, Kido K, Webber G, Fujii S, Wanless E, 'pH-Responsive Particle-Liquid Aggregates Electrostatic Formation Kinetics', Frontiers in Chemistry, 6 1-8 (2018) [C1]
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Nova |
2018 |
Thomas CA, Kido K, Kawashima H, Fujii S, Ireland PM, Webber GB, Wanless EJ, 'Electrostatic Formation of Polymer Particle Stabilised Liquid Marbles and Metastable Droplets - Effect of Latex Shell Conductivity', Journal of Colloid and Interface Science, 529 486-495 (2018) [C1]
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Nova |
2018 |
Ireland PM, Thomas CA, Lobel BT, Webber GB, Fujii S, Wanless EJ, 'An Electrostatic Method for Manufacturing Liquid Marbles and Particle-Stabilized Aggregates', FRONTIERS IN CHEMISTRY, 6 (2018) [C1]
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Nova |
2017 |
Cunningham VJ, Giakoumatos EC, Ireland PM, Mable CJ, Armes SP, Wanless EJ, 'Giant Pickering Droplets: Effect of Nanoparticle Size and Morphology on Stability', LANGMUIR, 33 7669-7679 (2017) [C1]
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Nova |
2016 |
Jarrett E, Ireland PM, Webber GB, Wanless EJ, 'Particle-liquid structures formed by electric fields', Powder Technology, 297 1-7 (2016) [C1]
We report the manufacture of complex structures of silica, coal or sphalerite particles around a water droplet, driven by an electrostatic field. A particle bed was deposited on a... [more]
We report the manufacture of complex structures of silica, coal or sphalerite particles around a water droplet, driven by an electrostatic field. A particle bed was deposited on an electrically biased substrate and an earthed water drop brought close, such that the particles jumped to the drop. These structures' shape and internal composition were determined by a combination of the particles' wettability and electrical properties, and other attributes such as shape, size and density were also thought to play a role. Hydrophilic particles tend to be internalised by the drop, while hydrophobic ones tend to form a layer or shell on the surface. Thus, one example of these structures was a 'complex liquid marble', with a hydrophilic particle suspension core and a stabilising shell of hydrophobic particles.
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Nova |
2016 |
Ireland PM, Noda M, Jarrett ED, Fujii S, Nakamura Y, Wanless EJ, Webber GB, 'Electrostatic formation of liquid marbles - Influence of drop and particle size', Powder Technology, 303 55-58 (2016) [C1]
We report the first study of the influence of drop and particle size on the electrostatic manufacture and subsequent stability of liquid marbles. It is clear from this study that ... [more]
We report the first study of the influence of drop and particle size on the electrostatic manufacture and subsequent stability of liquid marbles. It is clear from this study that the ¿rules¿ for electrostatic formation of liquid marbles are quite different for those for conventional direct-contact manufacture. Formation of liquid marbles was observed when an earthed water drop of volume 3¿7¿µL was brought into proximity with a bed of highly-charged polystyrene particles of diameter 22¿153¿µm. Under appropriate conditions the particles jumped to and coated the drop, producing a particle-liquid aggregate that dropped to the bed surface in the form of either a stable liquid marble or a particle-stabilised sessile drop. The subsequent evolution of the physical dimensions of the metastable aggregate was measured as the liquid drained into the bed, and its stability assessed. Formation of stable liquid marbles appeared to occur more easily for smaller drops and larger particles, and some of these considerably exceeded the conventionally-understood limit for the ratio of particle to drop size of stable liquid marbles.
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Nova |
2014 |
Ireland PM, Jameson GJ, 'Collision of a rising bubble-particle aggregate with a gas-liquid interface', International Journal of Mineral Processing, 130 1-7 (2014) [C1]
In this paper we investigate the hypothesis that when bubbles carrying attached hydrophobic particles arrive at an air-liquid interface, the abrupt change in velocity is sufficien... [more]
In this paper we investigate the hypothesis that when bubbles carrying attached hydrophobic particles arrive at an air-liquid interface, the abrupt change in velocity is sufficient to dislodge attached particles, which fall back into the liquid. For the first time, experiments have demonstrated a case in which the particles do not detach, but move smoothly over the surface of the bubbles. The kinetic energy of arrival is dissipated by the motion of the particles through the liquid, as they move over the surface of the bubble while remaining attached. Some energy is also dissipated by the pulsations of the bubbles. The pulsations themselves do not lead to detachment of particles. A theory has been developed to explain the observed phenomena. © 2014 Published by Elsevier B.V.
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Nova |
2013 |
Liyanaarachchi KR, Ireland PM, Webber GB, Galvin KP, 'Electrostatic formation of liquid marbles and agglomerates', APPLIED PHYSICS LETTERS, 103 (2013) [C1]
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Nova |
2013 |
Ireland PM, 'Convective mixing in a wet planar foam', Chemical Engineering Science, 101 554-564 (2013) [C1]
Buoyancy-driven convective flows have a substantial effect on the performance of the froth layer in flotation cells, particularly when wash water is applied, but are relatively po... [more]
Buoyancy-driven convective flows have a substantial effect on the performance of the froth layer in flotation cells, particularly when wash water is applied, but are relatively poorly understood. This study presents some experiments on convective flows in a foam undergoing forced drainage. A flat cell was used to create a planar foam, and a dye tracer was used to reveal the flow patterns, which were digitally imaged. The eddy scales and mixing behaviour of the flows are assessed using several different metrics, and their dependence on liquid and gas flow rates in the foam is assessed and compared. Finally, the implications of these findings for the effectiveness of wash water in flotation froths are discussed. © 2013.
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Nova |
2013 |
Ireland PM, Jameson GJ, 'Particle dynamics in cyclone tribochargers', JOURNAL OF ELECTROSTATICS, 71 449-455 (2013) [C1]
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Nova |
2012 |
Ireland PM, Jameson GJ, 'Drag force on a spherical particle moving through a foam: The role of wettability', International Journal of Mineral Processing, 102-103 78-88 (2012) [C1]
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Nova |
2012 |
Ireland PM, 'Dynamic particle-surface tribocharging: The role of shape and contact mode', Journal of Electrostatics, 70 524-531 (2012) [C1]
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Nova |
2011 |
Ireland PM, Nicholson K, 'Analysis and comparison of particle tribochargers', Minerals Engineering, 24 914-922 (2011) [C1]
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Nova |
2010 |
Ireland PM, 'Triboelectrification of particulate flows on surfaces: Part I - Experiments', Powder Technology, 198 189-198 (2010) [C1]
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Nova |
2010 |
Ireland PM, 'Triboelectrification of particulate flows on surfaces: Part II - Mechanisms and models', Powder Technology, 198 199-210 (2010) [C1]
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Nova |
2009 |
Ireland PM, Jameson GJ, 'Foam slip on surfaces of intermediate or low wettability', Chemical Engineering Science, 64 3859-3867 (2009) [C1]
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Nova |
2009 |
Ireland PM, 'Coalescence in a steady-state rising foam', Chemical Engineering Science, 64 4866-4874 (2009) [C1]
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Nova |
2009 |
Ireland PM, 'Contact charge accumulation and separation discharge', Journal of Electrostatics, 67 462-467 (2009) [C1]
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Nova |
2008 |
Ireland PM, 'Some curious observations of soap film contact lines', Chemical Engineering Science, 63 2174-2187 (2008) [C1]
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Nova |
2008 |
Ireland PM, 'The role of changing contact in sliding triboelectrification', Journal of Physics D: Applied Physics, 41 1-11 (2008) [C1]
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Nova |
2007 |
Ireland PM, Cunningham R, Jameson GJ, 'The behaviour of wash water injected into a froth', International Journal of Mineral Processing, 84 99-107 (2007) [C1]
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2007 |
Ireland PM, 'Some comments on contact charge relaxation', Applied Physics Letters, 91 091501 (2007) [C3]
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2007 |
Ireland PM, Jameson GJ, 'Liquid transport in a coalescing froth', Canadian Journal of Chemical Engineering, 85 654-661 (2007) [C1]
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2007 |
Ireland PM, Jameson GJ, 'Liquid transport in a multi-layer froth', Journal of Colloid and Interface Science, 314 207-213 (2007) [C1]
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Nova |
1995 |
Walker MA, Ireland PM, 'Rich cluster microlensing', Monthly Notices of the Royal Astronomical Society, 275 L41-L45 (1995)
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