Modelling droplet formation in cross-flow membrane emulsification (Abstract/Comunicazione in atti di convegno)

Type
Label
  • Modelling droplet formation in cross-flow membrane emulsification (Abstract/Comunicazione in atti di convegno) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • De Luca, G., Di Maio, F.P., Di Renzo, A., Drioli, E. (2006)
    Modelling droplet formation in cross-flow membrane emulsification
    in Euromembrane 2006, published on Desalination, Giardini Naxos (ME), Italy, 24-30/09/2006
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • De Luca, G., Di Maio, F.P., Di Renzo, A., Drioli, E. (literal)
Rivista
Note
  • Comunicazione (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Institute on Membrane Technology (ITM-CNR), via P. Bucci, Cubo 17C, 87036 Rende (CS), Italy Dipartimento di Ingegneria Chimica e dei Materiali, Universita della Calabria, via P. Bucci, Cubo 44A, 87036 Rende (CS), Italy (literal)
Titolo
  • Modelling droplet formation in cross-flow membrane emulsification (literal)
Abstract
  • Emulsions, used in food, pharmaceutical and cosmetic products as well as in many other industrial fields, are generally disperse systems of two (or more) immiscible liquids in which one phase (disperse phase) is distributed in form of droplets in the other phase (continuous phase). Both the droplet size and size distribution are important, since they determine the emulsion stability and its properties for intended uses. For large-scale emulsion productions, the most employed methods are based on the establishment of the turbulent flows (turbulent eddies) in the fluid mixture. According to known techniques, the droplets size is mainly determined by the time of exposure of these eddies and the size of the turbulent eddies. However, in these methods the turbulence cannot be controlled or generated uniformly throughout the mixture volume; the consequence is that scale-up is extremely difficult and energy is used inefficiently. Moreover, it is not possible to control accurately the droplet size. Recently, more attention has been addressed to an alternative emulsification process, i.e. the Cross-flow Direct Membrane Emulsification (CDME). In this procedure, the homogeneous phase to be dispersed is compressed to flow through a micro-porous membrane and reach the cross-flowing continuous phase on the other side of the membrane. Droplets formed at the membrane surface grow until their size reaches a critical value. Then, they are carried away by the continuous phase flowing in parallel to the membrane surface. In this procedure both droplet size and size distribution can be carefully and easily controlled by choosing suitable membranes and focussing on some key process parameters. Cross-flow membrane emulsification is an efficient process because the energy density requirement (energy input per volume of emulsion produced) is low compared to other emulsification processes. This lower energy density requirement improves the quality and functionality of delicate emulsion ingredients. The droplet size in a CDME depends generally on: operating parameters, i.e. cross-flow velocity, trans-membrane pressure; membrane characteristics, i.e. pore size and morphology, hydrophobicity/hydrophilicity of the membrane surface; phase properties, i.e. interfacial tension, viscosity and density of the processed phases. The aim of this contribution is to propose a model based on a novel set of force balance equations to predict the average diameter of droplets forming during cross-flow membrane emulsification. In particular, the dependence of droplet sizes on the above mentioned parameters is investigated from a fundamental point of view. Model validation is accomplished by using experimental data reported in literature. (literal)
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