Silicate dissolution kinetics

One parameter necessary for modeling silicate dissolution kinetics is the influence of aqueous chemistry on the rate expression. 

As numerous studies of aluminum silicates dissolution kinetics show, their max dissolution rate is noticeably increasing with growth in medium acidity or alkalinity. In neutral water they, as a regular rule, have minimal values (Figure 2.52). Correlation parameters of the dissolution rates for individual primary and secondary aluminum silicates are included in Table 2.24. 

Dissolution rates vary in the same way as these modeled concentrations (Fig. 5). The slow dissolution kinetics is enhanced by rapid adsorption reactions, and the extent of adsorption varies with pH, just as in the case of the iron dimer. Similar trends are found for other silicates, and a strong case can be made for surface-speciation control on inorganic silicate dissolution kinetics (Schott and Petit 1988 Brady and Walther 1989 Stumm and Wieland 1990). 

Blum, A. E. and Stillings, L. L. (1995). Feldspar dissolution kinetics. In "Chemical Weathering Rates of Silicate Minerals" (A. F. White and S. L. 

Blum, A.E. Stillings, L.L. 1995. Felsdpar dissolution kinetics. In White, A.F. Brantley, S.L. (ed.), Reviews in mineralogy, 31 Chemical weathering rates of silicate minerals, Mineralogical Society of America, USA, 291-352. 

Koretsky, E. M., Sverjensky, D. A., and Sahai, N. (1998). A model of surface site types on oxide and silicate minerals based on crystal chemistry— implications for site types and densities, multisite adsorption, surface infrared-spectroscopy, and dissolution kinetics. Amer. J. Sci. 298, 349-438. 

Dissolution Kinetics of Silicate Rocks—Application to Solute Modeling... 

WHITE AND CLAASSEN Dissolution Kinetics of Silicate Rocks... 

Experimentally determined dissolution kinetics are applicable to natural weathering processes of silicate rocks. Mass transfer from the mineral to the aqueous phase was determined to be incon-gruent under a range of experimental conditions. Transfer rates of individual species (Q) at times (t) can usually be described by one of two rate expressions ... 

Luce, R. W., Bartlett, R. W., and Parks, G. A. Dissolution kinetics of magnesium silicates, Geochim. Cosmochim. Acta 35-50 (1972). 

White, A. F., and Claassen, H. C. Dissolution kinetics of silicate rocks, application to solute modeling, JjL Jenne, E.A., ed., Chemical Modeling—Speciation, Sorption, Solubility, and Kinetics in Aqueous Systems, Am. Chem. Soc., 1978 (this volume). 

Xiao Y. and Lasaga A. C. (1995) Ah initio quantum mechanical studies of the kinetics and mechanisms of silicate dissolution H" " (HsO ) catalysis. Geochim. Cosmochim. Acta 58, 5379-5400. 

Xie Z. (1994) Surface properties of silicates, their solubility and dissolution kinetics. PhD, Northwestern University. 

Field observations implicating the importance of aluminosilicates to opal diagenesis were followed by laboratory experiments to determine the effect of Al(lll) derived from detrital aluminum silicate on the solubility and dissolution kinetics of opal. Dixit et al. (2001) mixed opal-rich ( 90% Si02) sediments from the Southern Ocean with different amounts of either kaolinite or ground basalt in long-term (21 months) batch... 

Holdren G. R. and Adams J. E. (1982) Parabohc dissolution kinetics of silicate minerals an artifact of nonequlibrium precipitation processes Geology 10, 186-190. 

Figure 13.6. (a) Linear dissolution kinetics observed for the dissolution of 6-AI2O3, representative of processes whose rates are controlled by a surface reaction and not by a transport step. (Data from Furrer and Stumm, (1986).) (b) Linear dissolution kinetics of frame silicates. Minerals used were pyroxenes and olivines their essential structural feature is the linkage of Si04 tetrahedra, laterally linked by bivalent cat-Fe -, Ca ). Plotted ate... 

Xiao, Y., and Lasaga, A. C. (1994) Ab-initio Quantum Mechanical Studies of the Kinetics and Mechanisms of Silicate Dissolution (H30 ) Catalysis, Geochim. 

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