CALORIMETRIC INVESTIGATIONS OF THE ADSORPTION OF WATER ON PALYGORSKITE DEGASSED AT VARIOUS TEMPERATURES

The isotherms and differential heats of adsorption of water onto palyg orskite, subjected to a vacuum pretreatment at 26, 70, and 150 degrees C, were studied. The heats of the interaction of weakly bound (zeolit e) and coordination-bound water with active sites of palygorskite were estimated. The high sensitivity of the calorimetric method allowed us to establish that reversible structural changes of palygorskite set i n already as a result of its vacuum treatment at room temperature, and to monitor the development of reversible structural changes in the mi neral as the vacuum treatment temperature was raised up to 150 degrees C.