The modification of hydroxyl surfaces of formamide-intercalated kaolinitessynthesized by controlled rate thermal analysis

Controlled rate thermal analysis (CRTA) technology made possible the separa tion of adsorbed formamide from intercalated formamide in formamide-interca lated kaolinites. X-ray diffraction shows that the CRTA-treated formamide-i ntercalated kaolinites remain expanded after CRTA treatment. The Raman spec tra of the CRTA-treated formamide-intercalated kaolinites are significantly different from those of the intercalated kaolinites with both intercalated and adsorbed formamide, An intense band is observed at 3629 cm(-1), attrib uted to the inner surface hydroxyls hydrogen bonded to the formamide. Broad bands are observed at 3600 and 3639 cm(-1) and are attributed to the inner surface hydroxyls, which are hydrogen bonded to the adsorbed water molecul es. The hydroxyl stretching band of the inner hydroxyl is readily observed at 3621 cm(-1) in the Raman spectra of the CRTA-treated formamide-intercala ted kaolinites. The results of thermal analysis show that the amount of int ercalated formamide between the kaolinite layers is independent of the pres ence of water, The Raman bands of the formamide in the CRTA-treated interca lated kaolinites are readily observed. (C) 2001 academic Press.