Aggregation of Methylene Blue in Frozen Aqueous Solutions Studied by Absorption Spectroscopy

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Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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HEGER Dominik JIRKOVSKÝ Jaromír KLÁN Petr

Rok publikování 2005
Druh Článek v odborném periodiku
Časopis / Zdroj Journal of Physical Chemistry A
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Obor Fyzikální chemie a teoretická chemie
Klíčová slova photochemistry; aggregation; methylene blue
Popis The paper presents a qualitative as well as quantitative spectroscopic study of methylene blue (MB) aggregation that occurs upon freezing the aqueous solutions over a wide concentration range. The Gaussian curve analysis and the multivariate curve resolution-alternating least squares method were used to determine the number and concentration of chemical species responsible for the overlaying absorption visible spectra measured. The results show the extent of aggregation for the concentrations above 10(-7) mol L(-1), being dependent on the freezing rate and the initial concentration. While the local concentration of MB at the grain boundaries of polycrystalline ice increased by approximately 3 orders of magnitude upon fast freezing at 77 K compared to the liquid phase, the concentration raised at least by 6 orders of magnitude upon slow freezing at 243 K. Since enhancement of the local concentration of solutes plays an important role in (photo)chemical transformations in solid aqueous media, this work helps to understand how the initial conditions control the course of the process. The results are relevant in other interdisciplinary fields, such as environmental chemistry, cosmochemistry, or geochemistry.
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