THEORETICAL STUDY OF THE HYDROLYSIS OF ALUMINUM COMPLEXES, ACTA UNIVERSITATIS OULUENSIS A Sci e n t i a e Rerum Nat u r a l i u m 554

This thesis focuses on the molecular-level chemistry of the solvation of aluminum salts.\nFundamental aspects such as, structural characteristics of the aluminum molecules, hydrolysis,\nacidity, solvation structure, effect of counter ions, and chemical stability are discussed herein.\nStatic computations augmented with the conductor-like screening model (COSMO) were used to\ninvestigate hundreds of planar and cyclic configurations of dimeric, trimeric, tetrameric, and\npentameric aluminum complexes. Car–Parrinello molecular dynamics (CPMD) calculations were\nused to expand investigations to aqueous environments.\nThis thesis consists of four articles and one additional article. The first paper focuses on the\nstructural analysis of the hydrolysis products of AlCl3 · 6H2O. Dimeric, trimeric, and tetrameric\naluminum (chloro)hydroxides were investigated in both gas and liquid phase. The liquid\nenvironment was modeled by using COSMO.\nThe second and the additional paper concentrate on the chemistry of aluminum sulfate\ncomplexes. The second article focuses on identifying hydrolysis products of AlCl3 · 6H2O in the\npresence of sulfate (H2SO4). The additional paper focuses on the structural characteristics of the\nhydrolysis products of Al2 (SO4)3 · 18H2O. Structural information was deduced from the ESI MS\nresults with the aid of computational methods. Detected cationic structures closely resembled the\naluminum chlorohydrate analogues introduced in the first paper.\nThe third and fourth articles are devoted to the hydrolysis, stability, and dynamics of dimeric\nand pentameric aluminum (chloro)hydroxides in aquatic environments. During the CPMD\nsimulations, several spontaneous associative hydration reactions were detected in the primary\nhydration shell of the complexes. Dimeric aluminum chlorohydrates were detected to be stable in\nliquid conditions, whereas the pentameric aluminum complexes experienced significant\ntopological changes during the simulations. Constrained simulations were used to reveal the role\nof chloride ions in the hydrolysis processes of dimeric complexes. The effect of the empirical van\nder Waals corrections to the dynamics of the simulations was also tested for the pentameric\nsystem.\nThe results of this thesis showed unequivocally that computational chemistry provides\neffective tools for structural analysis of inorganic complexes such as, aluminum chlorohydrates\nand sulfates in both gas and liquid phase. In addition, calculations provided answers to the\nanomalies detected in the experiments. Hence, theoretical methods are highly recommended to be\nused alongside with conventional experimental methods in the interpretation of the aluminum\nspecies in aqueous solutions and to widen the overall chemical perspective of the hydrolysis of\naluminum salts.

ISBN-10:
978-951-42-6182-4
Kieli:
eng.
Sivumäärä:
148 s.
Tekijät:
Saukkoriipi Jaakko
Tuotekoodi 013967
20,00 €