Project Details
Projekt
Predicting Crystal Growth using Molecular Modelling - Considering the Driving Force
Applicant
Professor Dr.-Ing. Joachim Ulrich, since 8/2008
Subject Area
Chemical and Thermal Process Engineering
Term
from 2005 to 2010
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 14638896
Crystal shape is a critical factor in determining solid product properties as well as the efficiency of downstream processing steps such as solid/liquid separation. It is therefore important not only to control the crystal size during a crystallization step, but also to ensure that the shape of the crystals is not detrimental to the product and its properties. Crystal habit can be controlled by factors such as the driving force (supersaturation or undercooling), the nature of the solvent used (in the case of solution crystallization) or the presence of heteromolecules, either impurities introduced by the materials employed or via preceding processing steps or growth modifying additives deliberately employed. In order to control the growth of crystals and therefore their habit, it is necessary to understand the factors that govern individual face growth. The prediction of crystal habit requires that one is able to quantify these factors. This is currently possible with respect to the equilibrium habit of a crystal, which depends only upon the internal structure of the crystal and not upon external factors governed by the growth environment, These methods have been implemented in commercial software, but frequently fail to correctly predict the growth habit of given crystalline materials. The growth habit is governed by external factors and to date no standard, routinely applicable method exists to calculate the habit accounting for the growth environment. To provide such a methodology is the objective of this project. Crystal growth will be described with explicit consideration of the growth environment. Molecular dynamics simulations of solid/liquid interfaces will be employed to derive rates of mass transfer that can be used in growth rate calculations. Particular attention will be paid to the growth environment in the vicinity of the solid surface. The effect of changing supersaturation or undercooling, factors that can easily be imposed upon the simulations, upon mass transfer will be studied. The expected outcome of the work is a methodology that allows reliable determination of growth habit.
DFG Programme
Priority Programmes
Ehemaliger Antragsteller
Dr. Matthew Jones, until 8/2008
