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Particle Shape and Purity in Membrane Based Crystallization
Author(s) -
Weckesser D.,
König A.
Publication year - 2008
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200700190
Subject(s) - crystallization , supersaturation , evaporation , crystal growth , materials science , membrane , growth rate , mass transfer , chemical engineering , particle size , particle (ecology) , impurity , crystal (programming language) , analytical chemistry (journal) , chemistry , crystallography , chromatography , thermodynamics , biochemistry , physics , geometry , mathematics , oceanography , organic chemistry , programming language , computer science , engineering , geology
Well‐controlled crystallization is the best method for preparing materials that are uniform in shape, size, structure and purity. The driving forces for crystallization are local gradients of supersaturation as the source and desupersaturation as the drain. Very high local supersaturation causes a high growth rate and represents a limiting factor for unstable modifications and product impurities. Hybrid membrane technology provides an interesting tool for controlling and limiting the maximum level of supersaturation due to defined mass transfer across the membrane. In this paper, the level of crystal growth rate in the system NaCl/KCl/water is varied by using different crystallization techniques. Vacuum evaporation crystallization (high growth rate) is compared to membrane based evaporation crystallization (low growth rate) and the results are interpreted in terms of product purity, particle shape and size. Membrane based crystallization in combination with effective solid/liquid separation as well as high performance analytics is suggested as a significant ultrapurification methodology.