The enthalpy of hydration of purified clinoptilolite from Beli Plast, Bulga
ria, and various cation-exchanged types such as Na-, K-, Ca- and Mg-clinopt
ilolite was determined by the adiabatic water-vapor absorption calorimeter.
The hydration enthalpy becomes more exothermic in the sequence K, Na, Ca,
Mg depending on hydration energy values of exchanged cations. Na-clinoptilo
lite would be an efficient heat exchanger in a wide temperature range of de
hydration, 180-300 degreesC, while Mg-clinoptilolite in higher temperatures
, 300-350 degreesC.