Clays and Clay Minerals

, Volume 45, Issue 6, pp 826–833 | Cite as

Calorimetric Measurement of the Enthalpy of Hydration of Clinoptilolite

  • J. William Carey
  • David L. Bish


The enthalpy of hydration of natural clinoptilolite was determined by isothermal immersion calorimetry on Ca-, Na- and K-exchanged clinoptilolite (Fish Creek Mountains, Nevada). Heats of immersion of clinoptilolite were determined at initial H2O contents ranging from θ = 0.02 to 0.85 (where θ is the ratio [H2O content]/[maximum H2O content]). The heat of immersion (liquid H2O reference state) of Ca-clinoptilolite ranged from -7.5 (θ = 0.87) to -25.7 kJ/mol-H2O (θ = 0.19); values for Na-clinoptilolite ranged from -6.3 (θ = 0.85) to -21.8 kJ/mol-H2O (θ = 0.11); and values for K-clinoptilolite ranged from -7.7 (θ = 0.80) to -24.6 kJ/mol-H2O (θ = 0.02). Linear regression of the calorimetric data provided the following values for the complete heat of immersion (from θ = 0): Ca-clinoptilolite, -30.3 ± 2.0; Na-clinoptilolite, -23.4 ± 0.6; and K-clinoptilolite, -22.4 ± 0.8 kJ/mol-H2O.

The heat of immersion measurements were compared with the enthalpy of hydration results of Carey and Bish (1996) determined in a thermogravimetric study of the same samples. The heat of immersion data are similar but of smaller magnitude than the values of enthalpy of hydration and are believed to be more accurate because they represent direct measurements of this thermodynamic property.

The effect of dehydration of clinoptilolite on the thermal evolution of the potential high-level radioactive waste repository at Yucca Mountain was considered by comparing the amount of energy consumed by clinoptilolite dehydration with the amount of energy necessary to heat rocks lacking hydrous minerals. The extra energy consumed on heating clinoptilolite from 25 to 200 °C ranges between 70 and 80% in excess of that required for nondehydrating materials (that is, clinoptilolite acts as a heat sink). These results indicate that accurate thermohydrologic modeling of rock units at Yucca Mountain should consider the thermal effect of dehydration/hydration processes in clinoptilolite and other hydrous minerals, in addition to the water produced/adsorbed during heating/cooling.

Key Words

Calorimetry Clinoptilolite Energetics Enthalpy Hydration Zeolite 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Barrer RM, Cram PJ. 1971. Heats of immersion of outgassed and ion-exchanged zeolites. In: Flanigen EM, Sand LB, editors. Molecular sieve zeolites—II. Washington, DC: Am Chem Soc. p 105–131.CrossRefGoogle Scholar
  2. Bish DL. 1988. Effects of composition on the dehydration behavior of clinoptilolite and heulandite. In: Kalló D, Sherry, HS, editors. Occurrence, properties and utilization of natural zeolites. Budapest: Akadémiai Kiadó. p 565–576.Google Scholar
  3. Bish DL, Chipera SJ. 1989. Revised mineralogic summary of Yucca Mountain, Nevada. Los Alamos Nat Lab Rept LA-1149-MS. 68 p.Google Scholar
  4. Carey JW, Bish DL. 1996. Equilibrium in the clinoptilolite-H2O system. Am Mineral 81:952–962.CrossRefGoogle Scholar
  5. Carey JW, Navrotsky A. 1992. The molar enthalpy of dehydration of cordierite. Am Mineral 77:930–936.Google Scholar
  6. Chipera SJ, Guthrie GD, Jr, Bish DL. 1993. Preparation and purification of mineral dusts. In: Guthrie GD, Mossman, BT, editors. Health effects of mineral dusts. Washington, DC: Mineral Soc Am. p 235–249.CrossRefGoogle Scholar
  7. Deming WE. 1943. Statistical adjustment of data. New York: J Wiley. 261 p.Google Scholar
  8. Gottardi G, Galli E. 1985. Natural zeolites. Berlin: Springer-Verlag. 409 p.CrossRefGoogle Scholar
  9. Johnson GK, Tasker IR, Jurgens R, O’Hare PAG. 1991. Thermodynamic studies of zeolites: Clinoptilolite. J Chem Thermo 23:475–484.CrossRefGoogle Scholar
  10. Loeven C. 1993. A summary and discussion of hydrologic data from the Calico Hills nonwelded Hydrogeologie unit at Yucca Mountain, Nevada. Los Alamos Nat Lab Rept LA-12376-MS. 102 p.Google Scholar
  11. Ross S, Olivier JP. 1964. On physical adsorption. New York: Interscience Publ 401 p.Google Scholar
  12. Vaniman DT, Bish DL. 1995. The importance of zeolites in the potential high-level radioactive waste repository at Yucca Mountain, Nevada. In: Ming DW, Mumpton FA, editors. Zeolites ’93. Brockport, NY: Int Committee on Natural Zeolites. p. 533–546.Google Scholar

Copyright information

© The Clay Minerals Society 1997

Authors and Affiliations

  • J. William Carey
    • 1
  • David L. Bish
    • 1
  1. 1.EES-1, MS D469, Los Alamos National LaboratoryLos AlamosUSA

Personalised recommendations