Crystal growth in porous materials—Ⅰ: The crystallization pressure of large crystals

摘要

A critical review of the existing literature on the pressure exerted by growing crystals in porous materials reveals that a number of different equations are in use. A derivation of an equation for the crystallization pressure based on the chemical potentials of the loaded and the unloaded faces of a growing crystal is provided. The equation obtained is compared to other equations available in the literature and the different approaches are discussed in detail. The treatment also includes the non-ideal behavior of the liquid phase using the ion interaction approach (Pitzer equations) which is well-established in solution thermodynamics. Incorporating the ion interaction equations in the crystallization pressure equation yields a quite simple expression that appears to be more convenient than previous treatments. The equation is applied to calculate crystallization pressures for supersaturated solutions of aqueous NaCl, NaNO_3, Na_2SO_4, and MgSO_4 including the various hydrated forms of these salts. Depending on the nature of the salt, neglecting the non-ideal behavior may cause considerable error in crystallization pressure calculations. Finally, it is emphasized that the basic assumption of non-uniform pressure is fundamental to understand the dynamics of crystallization pressure evolving in porous materials.