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Einfluß der Behandlung mit überkritischem Carbondioxid auf die Benetzbarkeit von Pulvern

Sabrina Gericke, Manfred Wolf und Klaus-Jürgen Steffens

Pharmazeutisches Institut, Pharmazeutische Technologie, Rheinische Friedrich-Wilhelms-Universität, Bonn

Influence of the Treatment with Super-critical Carbon Dioxide on Particle Wettability

In the pharmaceutical industry the micronization and the surface treatment with supercritical fluids become more and more important. A gas becomes a supercritical fluid, if pressure and temperature lie over the critical pressure ( pc) and critical temperature (Tc). In this condition there are no visible phase boundaries, that is both phases turn constantly from one into one another. A gas cannot be liquefied any longer: gas and liquid possess the same density. The study has shown how far the treatment with supercritical CO₂ has an influence on the wettability of a-lactose monohydrate. The measurements were carried out using the contact angle according to the Washburn method. After treatment with supercritical CO₂ the water uptake of sieved a-lactose monohydrate is clearly reduced while the contact angle is increased. The hydrophilic surface becomes more lipophilic, the polarity decreases and the result is a “smooth-surface”.

Key words a-Lactose Monohydrat · Benetzbarkeit · Kontaktwinkel · Überkritisches CO₂