Intercalation complexes of three different Hungarian kaolinites with hydrazine and potassium acetate were investigated by FT-IR (DRIFT) spectrometry, X-ray diffraction, and thermogravimetry combined with mass spectrometry. Differences were found in the thermal behaviour of the complexes as well as in the rehydration -reexpansion patterns of the heated intercalates. An XRD method is proposed for the distinction of kaolinite and 7.2 A halloysite present in the same mineral.
Abstract--Intercalation complexes of a Hungarian kaolinite were prepared with hydrazine and potassium acetate. The thermal behavior and decomposition of the kaolinite-potassium acetate complex was studied by simultaneous TA-EGA, XRD, and FTIR methods. The intercalation complex is stable up to 300"C, and decomposition takes place in two stages after melting of potassium acetate intercalated in the interlayer spaces. Dehydroxylation occurred, in the presence of a molten phase, at a lower temperature than for the pure kaolinite. FTIR studies revealed that there is a sequence of dehydroxylation for the various OH groups of intercalated kaolinite. The reaction mechanism was followed up to 1000"(2 via identification of the gaseous and solid decomposition products formed: H20, CO2, CO, C3H60, intercalated phases with basal spacings of 14.1 /~,, 11.5 /~, and 8.5 /~ as well as elemental carbon, I~H2(CO3)3" 1.5H20, K2CO3-1.5H20, and KAISiO4.
The redox behaviour of some new iron complexes has been studied in both acidic and alkaline solutions. The complexes were adsorbed irreversibly at the pyrolytic graphite disc of a rotating ring(Pt)-disc electrode (RRDE) from a 10-3M solution of the complex in N,N-dimethylformamide (DMF). Moreover, the electrocatalytic properties of these complexes for the cathodic reduction of oxygen were investigated. Both the redox behaviour and the electrocatalytic effect are discussed in relation to the medium composition as well as the molecular structure of the complex.
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