Fourier Transform Infrared Spectrophotometry and X-ray powder Diffractometry as Complementary Techniques in characterizing Clay size fraction of Kaolin

This study aimed at demonstrating complementary roles offered by both Fourier transform infrared (FTIR) spectrophotometry and x-ray powder diffraction (XRPD) techniques in characterizing clay size fraction of kaolins. The clay size fraction of kaolin samples obtained from Kgwakgwe, Makoro, Lobatse and Serule kaolin occurrences and deposits in Botswana were characterized using laser diffraction particle size analyzer (LDPSA), FTIR spectrophotometry and XRPD techniques. More than 70 wt % of the clay size fraction of these samples were 4 μm. Main peaks in the infrared spectra reflected Al-OH, Al-O and Si-O functional groups in the high frequency stretching and low frequency bending modes and were those for kaolinite but possible absorption interference peaks for quartz, smectite and muscovite are inferred. The XRPD results identified kaolinite as the major mineral phase with confirmed presence of quartz, smectite and muscovite as minor quantities in the samples. The findings therefore suggest that XRPD technique could be used as a complementary tool when characterizing the clay fraction of kaolin using FTIR spectrophotometry.