Mid-infrared and near-infrared spectroscopic study of kaolinite-potassium acetate intercalation complex

Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to elucidate the molecular structure of potassium acetate intercalated kaolinite and to determine the structural changes of kaolinite through intercalation. Based on analysis of the features and assignment for bands of MIR spectra, the NIR spectra provide the significant differences and the obvious structural change between kaolinite and the kaolinite-KAc intercalation complex. Detailed analysis of the NIR region is performed by comparing the first overtone (2νOH) and combination (ν + δ)OH bands with the fundamental stretching (ν) and bending (δ) vibrations. The NIR spectrum of the kaolinite-KAc intercalation complex shows decrease after intercalation in the intensities of the structural OH vibrations overtone (7300–7000 cm−1) and the combination (4600–4300 cm−1) bands. Therefore, the application of the technique across the entire infrared region is expected to become more routine and extend its usefulness, and the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.