THE ROLE OF WATER IN THE INTERCALATION OF KAOLINITE WITH POTASSIUM ACETATE

Water in intercalated kaolinites is observed first as bands in the hyd roxyl-stretching region at 3300 to 3550 cm(-1) and by the water H-O-H bending vibrations in the 1560 to 1680-cm(-1) region. For potassium-ac etate-intercalated kaolinite, hydroxyl-stretching bands attributed to water are observed at similar to 3540, similar to 3475, similar to 343 0, and similar to 3380 cm(-1). Water bending modes are observed at 156 0, 1586, 1610, and 1679 cm(-1). These bands are attributed to (a) wate r molecules adsorbed on the kaolinite surface, (b) zeolitic water, (c) molecular first layer water, and (d) ordered water on the hydroxyl su rface, respectively. The intensities of the bands are a function of th e method of preparation of the intercalated kaolinite, As the kaolinit e was washed for varying time intervals, the 1560 cm(-1) band decrease d in intensity more rapidly than the 1610 cm(-1) band. Even after wash ing for 24 h significant concentrations of water remained on the kaoli nite and only heating removed the water. The 1560, 1586, and 1610 cm-l bands are attributed (a) to free or non-hydrogen-bonded water held in the interlayer spaces of the kaolinite, (b) to water in the hydration sphere of the potassium ion, and (c) to surface-adsorbed water on the kaolinite layers, In kaolinites intercalated under pressure, an addit ional band was observed at 1679 cm-l. It is proposed that this band is due to water coordinated to the kaolinite surface. (C) 1998 Academic Press.