Papers by Marijana Dragosavac
Encyclopedia of Membranes, 2015
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Conventional devices for preparing emulsions (high pressure, ultrasonic homogenisers, colloid mil... more Conventional devices for preparing emulsions (high pressure, ultrasonic homogenisers, colloid mills, rotor–stator systems, microfluidisers) apply more energy than needed for the production of monosized droplets, leading to droplets with a wide size distribution. Membrane emulsification is a dispersion process to produce a monosized emulsion of one liquid phase (eg oil) in a second immiscible liquid phase (eg water) using low energy per unit volume where the shear stress applied on the membrane surface mainly influences ...
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Colloids and surfaces B: Biointerfaces
Co-encapsulation of drugs in the same carrier, as well as the development of microencapsulation p... more Co-encapsulation of drugs in the same carrier, as well as the development of microencapsulation processes for biomolecules using mild operating conditions, and the production of particles with tailored size and uniformity are major challenges for encapsulation technologies. In the present work, a suitable method consisting of the combination of membrane emulsification with solvent diffusion is reported for the production of multi-core matrix particles with tailored size and potential application in multi-therapies. In the emulsification step, the production of a W/O/W emulsion was carried out using a batch Dispersion Cell for formulation testing and subsequently a continuous azimuthally oscillating membrane emulsification system for the scaling-up of the process to higher capacities. In both cases precise and gentle control of droplet size and uniformity of the W/O/W emulsion was achieved, preserving the encapsulation of the drug model within the droplet. Multi-core matrix particles...
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Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
ABSTRACT Food-grade water-in-oil-in-water (W/O/W) multiple emulsions with a volume median diamete... more ABSTRACT Food-grade water-in-oil-in-water (W/O/W) multiple emulsions with a volume median diameter of outer droplets of 50-210 mu m were produced by injecting a water-in-oil (W/O) emulsion at the flux of 30 L m(-2) h(-1) through a 10-mu m pore electroplated nickel membrane oscillating at 10-90 Hz frequency and 0.1-5 mm amplitude in 2 wt% aqueous Tween(R) 20 (polyoxyethylene sorbitan monolaurate) solution. The oil phase in the primary W/O emulsion was 5 wt% PGPR (polyglycerol polyricinoleate) dissolved in sunflower oil and the content of water phase in the W/O emulsion was 30 vol%. The size of outer droplets was precisely controlled by the amplitude and frequency of membrane oscillation. Only 3-5% of the inner droplets with a mean diameter of 0.54 mu m were released into the outer aqueous phase during membrane emulsification. A sustained release of 200 ppm copper (II) loaded in the inner aqueous phase was investigated over 7 days. 95% of Cu(II) initially present in the inner water phase was released in the first 2 days from 56-mu m diameter multiple emulsion droplets and less than 15% of Cu(II) was released over the same interval from 122 mu m droplets. The release rate of Cu(II) decreased with increasing the size of outer droplets and followed non-zero-order kinetics with a release exponent of 0.3-0.5. The prepared multiple emulsions can be used for controlled release of hydrophilic actives in the pharmaceutical, food, and cosmetic industry.
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AIChE Journal, 2015
ABSTRACT A novel membrane emulsification system is reported consisting of a tubular metal membran... more ABSTRACT A novel membrane emulsification system is reported consisting of a tubular metal membrane, periodically azimuthally (tangentially) oscillated with frequencies up to 50 Hz and 7 mm displacement in a gently cross flowing continuous phase. A CFD analysis showed consistent axial shear at the membrane surface, which became negligible at distances from the membrane surface greater than 0.5 mm. For comparison, CFD analysis of a fully rotating membrane emulsification system showed local vortices in the continuous phase leading to a variable shear along the axis of the membrane. Using an azimuthally oscillating membrane, oil-in-water emulsions were experimentally produced with a median diameter of 20-120 µm, and a coefficient of variation of droplet size of 8%. The drop size was correlated with shear stress at the membrane surface using a force balance. In a single pass of continuous phase it was possible to achieve high dispersed phase concentrations of 40% v/v. This article is protected by copyright. All rights reserved.
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Chemical Engineering Research and Design, 2015
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Industrial & Engineering Chemistry Research, 2012
Tubular micron pore sized sieve type membranes with internal diameter of 14 mm and length of 60 m... more Tubular micron pore sized sieve type membranes with internal diameter of 14 mm and length of 60 mm containing uniform pores of diameter 10 and 20 μm were used to generate emulsions of sunflower oil dispersed in water and stabilised by Tween 20 using oscillatory flow of the continuous phase. Drop diameters between 30 and 300 μm could be produced, in a controllable way and with span values of down to 0.4. By using pulsed flow it was possible to provide dispersed phase concentrations of up to 45% v/v in a single pass over ...
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Food Research International, 2013
ABSTRACT
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(English) Emulsions are dispersed systems of two (or more) immiscible liquids, water and oil and ... more (English) Emulsions are dispersed systems of two (or more) immiscible liquids, water and oil and they play an important role in the formulation of pharmaceutical, food and cosmetic products. Uniform oil droplets can be used for encapsulation and controlled release of lipophilic active ingredients in various formulations. Oil-in-water emulsions have been prepared by injecting sunflower oil or pumpkin seed oil through flat nickel membrane into continuous phase (aqueous surfactant solution of Pluronic (R) F-68 or Tween (R) 20) ...
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Conventional devices for preparing emulsions (high pressure, ultrasonic homogenisers, colloid mil... more Conventional devices for preparing emulsions (high pressure, ultrasonic homogenisers, colloid mills, rotor–stator systems, microfluidisers) apply more energy than needed for the production of monosized droplets, leading to droplets with a wide size distribution. Membrane emulsification is a dispersion process to produce a monosized emulsion of one liquid phase (eg oil) in a second immiscible liquid phase (eg water) using low energy per unit volume where the shear stress applied on the membrane surface mainly influences ...
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Journal of Membrane Science, 2012
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Uniform oil droplets can be used for encapsulation and controlled release of lipophilic active in... more Uniform oil droplets can be used for encapsulation and controlled release of lipophilic active ingredients in various food, cosmetic, and pharmaceutical formulations. In these applications, uniform drops of controlled size are needed to achieve a controlled release at adjustable rates. In this work, O/W emulsions have been prepared by injecting sunflower oil through a flat disc nickel membrane into stirred continuous phase (aqueous solution of Tween® 20 or Pluronic® F-68). Three different membranes were used: 40μm whole ...
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Journal of Membrane Science, 2008
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Emulsions are multiphase dispersed systems consisting of two (or more) immiscible liquids, eg wat... more Emulsions are multiphase dispersed systems consisting of two (or more) immiscible liquids, eg water and oil. Depending on which is the dispersed phase and which is the continuous phase, there are two types of single emulsions: oil-in-water (O/W) and water-in-oil (W/O) emulsions. In this work, O/W emulsions have been prepared by injecting unrefined pumpkin seed oil through a nickel plate membrane into an aqueous surfactant solution (Tween® 20 or Pluronic® F-68 with a concentration of 2 mas/vol%). The pumpkin seed oil with a ...
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Emulsions are multiphase dispersed systems consisting of two (or more) immiscible liquids, eg wat... more Emulsions are multiphase dispersed systems consisting of two (or more) immiscible liquids, eg water and oil. Depending on which is the dispersed phase and which is the continuous phase, there are two types of single emulsions: oil-in-water (O/W) and water-in-oil (W/O) emulsions. In this work, O/W emulsions have been prepared by injecting unrefined pumpkin seed oil through a nickel plate membrane into an aqueous surfactant solution (Tween® 20 or Pluronic® F-68 with a concentration of 2 mas/vol%). The pumpkin seed oil with a ...
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Conventional methods for preparing of emulsions (high pressure homogenizers, colloid mills, rotor... more Conventional methods for preparing of emulsions (high pressure homogenizers, colloid mills, rotor–stator systems ultrasonic or microfluidizers) apply more energy then needed for production of droplets giving the droplets with wide range distribution. Membrane emulsification is a membraneassisted dispersion process to produce an emulsion of one liquid phase (such as oil) in a second immiscible liquid phase (such as water)[1].
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In many applications employing particles, the distribution of particle sizes has significant infl... more In many applications employing particles, the distribution of particle sizes has significant influence on the properties of the resultant material. Membrane emulsification (ME) is a method for manufacturing uniformly sized emulsion droplets where a dispersed phase is forced through a membrane into the continuous phase. It is the shear applied on the membrane surface that detaches the droplets thereby generating an emulsion.
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A membrane emulsification method for production of monodispersed silica-based ion exchange partic... more A membrane emulsification method for production of monodispersed silica-based ion exchange particles through water-in-oil emulsion route is developed. A hydrophobic microsieve membrane with 15 μm pore size and 200 μm pore spacing was used to produce droplets, with a mean size between 65 and 240 μm containing acidified sodium silicate solution (with 4 and 6 wt% SiO 2) in kerosene. After drying, the final silica particles had a mean size in the range between 30 and 70 μm.
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There has been an increasing interest in the production of functionalised porous silica microsphe... more There has been an increasing interest in the production of functionalised porous silica microspheres with particle diameters greater than 1 µm. A control of particle size and internal microstructure of silica particles is critically important in ion exchange, biochemical sensing, drug delivery, catalysis, and chromatography. This work reports a novel W/O emulsion route based on a microsieve-type membrane emulsification to prepare porous silica microspheres with a controllable size between 30 and 70 μm [1].
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Stirred cell membrane emulsification was used to create double water-in-oil-in-water emulsions at... more Stirred cell membrane emulsification was used to create double water-in-oil-in-water emulsions at the dispersed phase flux of up to 3200Lm− 2h− 1. The oil phase was unrefined pumpkin seed oil or sunflower oil containing 30% by volume of internal water phase and the external water phase was 2% Tween 20 (polyoxyethylene sorbitan monolaurate) or 2% Pluronic F-68 (polyoxyethylene-polyoxypropylen copolymer).
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