Naslov
Processes of nucleation and crystal growth in zeolite A synthesis

Autori
Palčić, Ana

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Prirodoslovno-matematički fakultet

Mjesto
Zagreb

Datum
13.07

Godina
2012

Stranica
88

Mentor
Bronić, Josip ; Subotić, Boris

Ključne riječi
zeolites ; nucleation ; crystal growth ; autocatalytic nucleation ; gel ageing ; gel density ; particulate properties

Sažetak
The zeolite A was obtained by hydrothermal treatment of aluminosilicate hydrogels at 80 °C. Some of the hydrogels were aged at 25 °C for various times and then hydrothermally treated under static and dynamic conditions. Other studied systems were hydrogels having different starting density. Hydrothermal treatment of these hydrogels began several moments after their preparation. Using kinetic data (rates of crystallization and crystal growth) and crystal size distributions of the zeolite A at the end of crystallization, the kinetics of nucleation and distribution of nuclei "within" the gel matrix were determined. It was found that the distribution of nuclei in gel matrix considerably changes with the time of hydrogel ageing while the change of the density of the starting gel does not show pronounced effect. The nuclei formed during the precipitation of hydrogel are non-homogeneously distributed within the gel matrix, while the new nuclei are formed at surface and sub-surface regions of gel's particles (aged systems) or "concentrated" closer to the centres of the gel's particles (fresh systems). The consequences of hydrogel ageing on crystallization course as well as the observed effects are discussed from viewpoint of particulate properties and the zeolite autocatalytic nucleation.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

Napomena
Rad je obranjen pred povjerenstvom u sastavu: dr.
sc. Dubravka Matković Čalogović, red. prof., PMF,
Zagreb ; dr. sc. Josip Bronić, v. zn. sur., IRB,
Zagreb, dr. sc. Boris Subotić, zn. savj., IRB,
Zagreb ; dr. sc. Marina Cindrić, red. prof., PMF,
Zagreb ; dr. sc. Valentin Valtchev, zn. savj.,
ENSICAEN, Caen, Francuska

POVEZANOST RADA