Lowson,R.T., Brown,P.L., Comarmond,M.-C.J. and Rajaratnam,G.(2007): The kinetics of chlorite dissolution. Geochimica et Cosmochimica Acta, 71, 1431-1447.

『緑泥石溶解のカイネティックス』


Abstract
 A model for the dissolution of chlorite has been developed based on fast ligand assisted proton attack of the alumina tetrahedra within the alumina-silica lattice followed by slower dissolution of the remnant silica lattice. While the rate determining step is within the silica dissolution regime, the rate is a function of the H+ and Al3+ concentrations and the dominant aqueous Al species. Individual rates may be described by a generic rate equation applicable across the spectrum of Al species:
rn = kn ((KnAlpLq(3p-zq))(aH+3p/aAl3+p)/(1 + (KnAlpLq(3p-zq))(aH+3p/aAl3+p)))τn,
where rn is the rate subscripted for the nth Al species, k is the rate constant of the rate controlling step K is the surface exchange constant, β is the solution stability constant subscripted for the Al species, a is the species activity subscripted for species and raised to the power of the stoichoimetry, p and q are stoichiometric coefficients, z is the ligand charge and τ is the fractional coefficient for the precursor of the rate defining step. The observed rate is the sum of the individual rates. When the observed rate is in a domain of dominance for a single aluminum species and in the absence of strong complexing agents such as oxalate, the observed rate is proportional to (aH+3/aAl3+)τn. The model is supported by experimental data for the dissolution of chlorite over a pH range of 3-10 and temperature range 25-95℃. The results have hydrometallurgical application.』

1. Introduction
2. Theory
 2.1. Background
 2.2. Theory
3. Experimental
 3.1. Method
4. Results
 4.1. Data
  4.1.1. Raw data
  4.1.2. Species calculations
  4.1.3. Solubility of chlorite
 4.2. Variation of reaction rate with H+ and Al3+
 4.3. The fractional coefficient, τn
 4.4. Energies of activation
5. Conclusions and applications
Acknowledgments
Appendix A
 A.1. Temperature corrections
 A.2. Variable flow corrections
 A.3. Simplification of the general rate expression for the case of mononuclear species
References



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