Basalt glass dissolution rates

Oelkers, E. H. Gislason, S. R. 2001. The mechanism, rates and consequences of basaltic glass dissolution I. An experimental study of the dissolution rates of basaltic glass as a function of aqueous Al, Si and oxalic acid concentration at 25 °C and pH = 3 and 11. Geochimica et Cosmochimica Acta, 65, 3671-3681. 

Crovisier, J. L., Honnorez, J. Eberhart, J. P. 1987. Dissolution of basaltic glass in seawater Mechanism and rate. Geochimica et Cosmochimica Acta, 51, 2977-2990. 

Here k is the rate constant, and Kj is the equihbrium constant for an exchange reaction between protons and the metal M, at the surface. Oelkers argues that when the term Kfa +la Y is small, significant M, remains in the surface leached layer, and the rate equation simplifies in that the denominator becomes unity. For such a case, the logarithm of the far-from-equilibrium rate becomes linearly related to the logarithm of the activity of the aqueous species M, and is dependent only upon pH and activity of M,. Oelkers (2001b) has used this simplified rate equation to describe dissolution of basalt glass... 

Figure 2,5 (a) An Arrhenius plot of log k versus I/TXK) for the dissolution rates of various silicate rocks and minerals. The data points and curves for rhyolite, basalt glass, and diabase are from Apps (1983), as is the curve labeled silicates, which Apps computed from the results of Wood and Walther (1983). Curves for the S1O2 polymorphs are based on Rimstidt and Barnes (1980). Modified from Langmuir and Mahoney (1985). Reprinted from the National Well Water Assoc. Used by permission, (b) An Arrhenius plot of log k versus 1 /T(K) for the precipitation of quartz and amorphous silica based on Rimstidt and Barnes (1980). Reprinted from Geochim. Cosmochim. Acta, 44, J.D. Rimstidt and H.L. Barnes, The kinetics of silica water reactions, 1683-99, 1980, with permission from Elsevier Science Ltd, The Boulevard. Langford Lane. Kidlington OXS 1GB, U.K. 

Figure 2. Plot of the dissolution rate of basalt glass versus solution pH at 50, 100, 150, and 200°C.

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