Kinetics and Thermodynamics

 

 
Thermodynamic and kinetic studies of mineral reactions are significant for a variety of processes effecting the movement of contaminants in the environment. Minerals are often effective at retarding or stopping the movement of contaminants in ground water by adsorption to surfaces or by intracrystalline absorption. Mineral precipitation and dissolution reactions also control rock or soil permeability, thereby controlling rates of ground water movement. We use kinetic and thermodynamic studies to predict whether sorption and precipitation/dissolution reactions will occur and at what rate. We use calorimetry (immersion calorimetry and differential scanning calorimetry) to obtain fundamental data on the thermodynamic properties of minerals. We use aqueous solution experiments to measure adsorption phenomena via column studies, batch studies, and are developing a flow-through capability. We examine kinetics of reactions with thermal analysis equipment and will extend this using flow-through apparatus. Finally, we are involved in the development of a theoretical understanding of sorption processes, particularly of H2O in zeolites and clays (see figure above).

Some of our recent work includes the following: calorimetric measurement of the heat of adsorption of H2O by the zeolite, clinoptilolite; thermogravimetric studies of sorption equilibria in the clinoptilolite-H2O system; calorimetric studies of surfactant-modified zeolites; sorption/precipitation studies in the Pb-Ca phosphate system; controlled-humidity investigation of hysteresis in the sorption behavior of smectite clays; and studies of the hydration properties of siliceous gels derived by cement hydration reactions.

Recent Publications and Abstracts:

"Calorimetric measurement of the enthalpy of hydration of clinoptilolite" J. W. Carey and D. L. Bish, Clays and Clay Minerals (submitted)

"Equilibrium in the clinoptilolite-H2O System" J. W. Carey and D. L: Bish, American Mineralogist 81: 652-962 (1996).

Calorimetric determination of the heat of sorption of surfactants (HDTMA and TEA) on clinoptilolite. J. W. Carey, E. J. Sullivan, and R. S. Bowman. CMS 96.

"Controlled-humidity XRD analyses: application to the study of smectite expansion/contraction" S. J. Chipera, J. W. Carey, and D. L. Bish. In Advances in X-ray Analyses Proceedings (in press).

"Consequences of the dehydration and hydration of clinoptilolite-rich rocks on the thermo-hydrologic evolution of a model radioactive waste repository". J. W. Carey, B. A. Robinson, S. Henderson. Geological Society of America Abstracts with Programs. GSA program with abstracts 1995.

"Hydration/dehydration hysteresis in smectite: equilibrium or kinetic effect?" S. J. Chipera, J. W. Carey, and D. L. Bish. Clay Mineral Society Meeting, 1996.

"Thermal behavior of natural zeolites." D. L. Bish, in D. W. Ming , and F. A. Mumpton , eds., Natural Zeolites '93, p. 259-269. International committee on Natural Zeolites, Brockport, NY, 1995.

For more information, contact Bill Carey (505-667-5540 or bcarey@lanl.gov).

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