Delamination of Kaolinite by Mechano-chemical Grinding.

Kaolinite was treated with urea to form urea - kaolinite complex, then delaminated by grinding using a mechanical mortar. The delaminated products and their deintercalated products were characterized by specific surface area measurement, X - ray diffraction and infrared absorption analysis. The results are summarized below. The specific surface area of the kaolinite treated with urea remarkably increased by grinding for more than 3 h. The basal spacing of the treated kaolinite increased due to the intercalation of urea into the kaolinite structure, and the decrease in attractive force acting between silicate layers of kaolinite. It caused that kaolinite was easily delaminated by grinding. The basal spacing of urea - kaolinite complex was decreased from 10.8 Å to 8.3 Å by boiling and washing. The 8.3 Å basal spacing is larger than the kaolinite (7.2 Å). This result indicates that a molecule decomposed from urea (NHCO) still remains in the kaolinite structure.