Graphs from the modification of the hydroxyl surface of potassium acetate intercalcated halloysite between 25 and 300 degrees celcius

Full description

Halloysite from Szeg, Hungary was analyzed for phase purity using X-ray diffraction techniques. The halloysite was purified by sedimentation and size fractionated to <20 μm. Three hundred milligrams were treated with 30 cm3 of 7.2 M potassium acetate solution. The sample was shaken for 80 hours in a constant temperature bath at ambient temperature. The excess solution on the clay was removed by centrifugation. The potassium acetate-intercalated halloysite was allowed to dry in air before analysis.

Figure 1 shows X-ray diffraction patterns of potassium acetate-intercalated halloysite heated to 250 °C and cooled to 25 °C under nitrogen.  Figure 2 is a graph showing crystallite size as a function of temperature upon heating and cooling.  Figure 3 is Raman spectra of the hydroxyl-stretching region of potassium acetate intercalated halloysite sequentially heated, as labeled. Figure 4 shows the variation of the peak position (a) bandwidth (b) of the hydroxyl-stretching bands of potassium acetate-intercalated halloysite as a function of temperature. Figure 5 shows Raman spectra of the hydroxyl deformation and C-C stretching region of potassium acetate-intercalated halloysite after heating to the prehydroxylation temperature and cooling to 25 °C.  Figure 6 is Raman spectra of the hydroxyl deformation and C-O stretching region of potassium acetate-intercalated halloysite after heating to the prehydroxylation temperature and cooling to 25 °C.  Figure 7 shows the variation of the relative intensities of the two CO2− symmetric stretching modes and the two acetate bonded inner surface hydroxyl stretching vibrations as a function of temperature.  Figure 8 Raman spectra of the OCO bending region of potassium acetate-intercalated halloysite after heating to the predehydroxylation temperature and cooling to 25 °C.