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ID: 242448.0, MPI für Dynamik komplexer technischer Systeme / Physical and Chemical Process Engineering
A Discrete-Continuous Population Balance Approach for the Nanoparticle Precipitation in Microemulsions
Authors:Niemann, B.; Sundmacher, K.
Date of Publication (YYYY-MM-DD):2006
Title of Proceedings:Conference proceedings, 06 AIChE spring national meeting ; Vol. 2: Fifth World Congress on Particle Technology : WCPT 5
Sequence Number:155e
Physical Description:CD-ROM
Name of Conference/Meeting:The Fifth World Congress on Particle Technology 2006 (WCPT)
Place of Conference/Meeting:Orlando, Florida
(Start) Date of Conference/Meeting
End Date of Conference/Meeting 
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The formation of nanoparticles in microemulsion droplets is a promising technology for the control of the particle properties, e.g. the particle size distribution or particle shape [1]. Due to the time consuming and expensive experiments in this field (e.g. complex phase behavior [2] and TEM analysis) a reasonable modelling strategy is an indispensable step for the process analysis.

Some stochastic and a few deterministic modelling approaches can be found in the literature (see overview in [3]). Most of these approaches have a very high computational demand because of the high number of internal coordinates which are necessary for a reliable description of the microemulsion system [3]. At least 3 internal coordinates (the two reactant concentrations inside the droplets and the particle size) have to be considered. Modelling approaches which combine the need of fast computational solutions, e.g. for online process control or CFD studies, and the high dimension of system can not be found in the literature so far. A novel discrete-continuous population balance approach [4] allows a very fast computational solution within a few seconds. The main assumption is a equilibrium distribution of the two reactants inside the droplets. Within in this approach the numbers of molecules/ions of the two reactants inside the droplets are described by a two-dimensional, discrete and time-dependent Poisson distribution [5]. The third internal coordinate of the droplet population, the particle size, is a partially discrete-continuous coordinate. The splitting of the coordinate in a discrete part for the small nuclei (nucleation and growth kinetics simultaneously) and a continuous part for bigger particles (only growth kinetics) enables a very accurate mass conservation of the whole system and a significant reduction of the model equations.

The presented model was validated with barium sulfate microemulsion based precipitation experiments in a semi-batch rushton tank reactor [6]. A good agreement between experimental and simulated particle size distributions was obtained for a set of experiments where the initial reactant concentrations inside the droplets have been used as a control parameter for the particle size.

[1] Kumar, P.; Mittal, K. L. (Eds): Handbook of Microemulsion Science and Technology, Marcel Dekker Inc., New York, 1999

[2] Rauscher, F.; Veit, P.; Sundmacher, K.: Analysis of a technical-grade w/o microemulsion and its application for the precipitation of calcium carbonate nanoparticles. In: Colloid Surf. A-Physicochem. Eng. Asp. 254 (1-3), p. 183-191, 2005

[3] Niemann, B.; Rauscher, F.; Adityawarman, D.; Voigt, A.; Sundmacher, K.: Microemulsion-assisted precipitation of particles: Experimental and model-based process analysis. In: Chem. Eng. & Proc., 2005, accepted

[4] Niemann, B.; Recksiedler, J.; Adityawarman, D.; Sundmacher, K.: Nucleation and growth kinetics for the nanoparticle precipitation of barium sulfate in microemulsions. AIChE 2005 Annual Meeting, Cincinnati, OH

[5] Bandyopadhyaya, R.; Kumar, R.; Gandhi, K. S.; Ramkrishna, D.: Modeling of precipitation in reverse micellar systems. In: Langmuir 13 (14), p. 3610-3620, 1997
External Publication Status:published
Document Type:Conference-Paper
Communicated by:Kai Sundmacher
Affiliations:MPI für Dynamik komplexer technischer Systeme/Physical and Chemical Process Engineering
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