Thermal Behavior and Decomposition of Intercalated Kaolinite

Abstract

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.

Thermal Behavior of the Kaolinite-Hydrazine Intercalation Complex

“…This expansion agrees with those reported previously (Weiss et al, 1963;Wada and Yamada, 1968;Johnston and Stone, 1990;G~ibor et al, 1995). Intercalation of hydrazine was almost complete after 1-h treatment, independently of the method used for preparation.…”

“…Intercalation of kaolinite by hydrazine was proposed as a method to differentiate a 7-,~ kaolin mineral from chlorite (14 A) by X-ray diffraction (Wada and Yamada, 1968). The intercalation method can characterize kaolinite with various degrees of lattice disorder and intercalation reactivity (Range et al, 1969;Fernfindez Gonz~ilez et al, 1976;Jackson and Abdel-Kader, 1978;Theng et al, 1984;G~ibor et al, 1995). Hydrazine was also used to induce artificial disorder in kaolinite (Barrios et al, 1977).…”

Positron Annihilation Lifetime Spectroscopy and Dielectric Measurements of Natural Kaolinite and Kaolinite Intercalated by Potassium Acetate

“…Spacings in natural kaolinite and in kaolinite intercalated by potassium acetate are similar to those obtained by other authors [2,13,14]. Using the obtained data it is possible to estimate the thickness of free part of interlayer space.…”

Esfoliação e hidratação da caulinita após intercalação com uréia

“…concentrado na caracterização e consequentemente localização dessas moléculas intercaladas [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] , além da intercalação de algumas moléculas específicas que possam ser substituídas por outras, não diretamente intercaláveis [32][33][34][35][36] (método do deslocamento). Uma das maneiras desenvolvidas recentemente, envolve o uso da caulinita hidratada que pode ser preparada tratando-se a caulinita organofuncionalizada, com álcoois ou água [37][38][39][40] .…”