ISOTOPIC EXCHANGE OF KAOLINITE HYDROXYL PROTONS - A DIFFUSE-REFLECTANCE INFRARED FOURIER-TRANSFORM SPECTROSCOPY STUDY

Specific surface reactions on kaolinite were investigated by deuterium exchange of the hydroxyl protons of kaolinite, The kaolinite samples were reacted with deuterium oxide for 48 h and 2.5 and 5 weeks, at var ious pH values (3, natural and 8) and at different temperatures (ambie nt, and 30, 60 and 100 degrees C), Analyses were performed using diffu se reflectance infrared Fourier transform (DRIFT) spectroscopy. The sp ectral results show that it is very difficult at room temperature to e xchange the hydroxyl protons isotopically with deuterons at the surfac e of kaolinite, The temperature and the reaction time must be increase d for successful exchange. It was found that the most suitable tempera ture for isotopic exchange was 60 degrees C. The pH did not significan tly influence the deuteration, Only at high pH were changes of the OD bands in the DRIFT spectra observed, This study shows that it is possi ble to deuterate kaolinite without using intercalation. All three type s of hydroxyl protons from the inner, inner surface and edge were exch anged.