Thermal Study of Types of Water Associated with Clinoptilolite

Gregory D. Knowlton, Ted R. White and H. Lawrence McKague
Arizona State University, Tempe, Arizona 85281
Lawrence Livermore National Laboratory, Livermore, California 94550

Abstract: The identification and quantification of the water associated with powdered clinoptilolite and clinoptilolite-bearing tuffs were made using thermogravimetric, vacuum gravimetric, and differential scanning calorimetric techniques. Inflection points on thermogravimetric curves at approximately 80° and 170°C correspond to changes in the proportions of externally adsorbed water to loosely bound zeolitic water and loosely bound zeolitic water to tightly bound zeolitic water, respectively. These three types of water can be differentiated by temperatures and heats of dehydration obtained from differential scanning calorimetry. These temperatures and heats of hydration are 75 ± 10°C and 59.2 ± 5.9 kJ/mole H2O, 171 ± 2°C and 58.7 ± 6.1 kJ/mole H2O, and 271 ± 4°C and 78.7 ± 7.0 kJ/mole H2O for external water, loosely bound water, and tightly bound water, respectively. The ratio of loosely bound zeolitic water to tightly bound zeolitic water determined in this study is similar to that reported in the literature from structural determinations, indicating that the desorption properties of clinoptilolite are determined by the specific positions of the water molecules in the structure.

Key Words: Clinoptilolite • Thermal analysis • Tuff • Water • Zeolite

Clays and Clay Minerals; October 1981 v. 29; no. 5; p. 403-411; DOI: 10.1346/CCMN.1981.0290510
© 1981, The Clay Minerals Society
Clay Minerals Society (www.clays.org)