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Quantitative Analysis of Silica in Silica-Kaolin Mixtures by Photoacoustic and Diffuse Reflectance Spectroscopies

Volume 46, Number 11 (Nov. 1992) Page 1719-1723

Pandurangi, Raghoottama S.; Seehra, Mohindar S.

The techniques of photoacoustic spectroscopy (PAS) and diffuse reflectance spectroscopy (DRS) are investigated for the quantification of silica using the IR bands at 1080, 797, 693, and 1875 cm−1. It is observed that, in both techniques, signal intensity increases linearly with mass initially. However, signal saturation sets in at much lower masses (>2 mg) in PAS than in DRS (>30 mg), showing that saturation is strongly technique dependent, in addition to having dependence on the absorptivity of the sample. These findings are applied to the quantification of silica in laboratory-generated silica-kaolin mixtures. It is shown that, with the use of the weaker band at 1875 cm−1 in DRS, satisfactory results for the quantification of silica are obtained.