Quantitative determination of surface silanol groups in silicagel by deuterium exchange combined with infrared spectroscopy and chemometrics

Concentration of silanol groups on silica gel surface has been quantitatively determined using the deuterium exchange method. Simple and effective procedures have been used in pre-sample drying, deuterium exchange and extraction of resulting isotopic mixture from the exchange reaction. Each of four silica gel samples with varying surface area has been subjected to pre-drying to remove adsorbed water and then quantitatively mixed with deuterium oxide in a steel bomb for isotopic exchange. The resulting D2O/water mixture was then extracted by applying high pressure using infrared pellet press. The infrared spectrum of the isotopic mixture was measured and the composition was then determined by a multivariate calibration model established between infrared profiles of water in D2O standard mixtures and their composition. The results show that the silanol group concentration determined agrees with the values reported in the literature.