H/D isotopic interpretation of hydration isotherms
Abstract
Various methods have been developped since years for describing the poral distribution of porous materials from hydration isotherms measurements. The most well known is the BJH method, which relies on a model of cylindric pores. More recently, methods (e.g. Or and Tuller, 1999) consider pores with various geometries (slit pores, pores with polygonal section), providing great improvements in the description of hydration isotherms and/or retention curves. However, these approaches are based on a series of assumptions (constant molar volume of hydration water, a priori geometrical characteristics of pores, no contact angle between adsorption film and capillary meniscus, etc). As a result, determination of the amount of water available for chemical reactions remains qualitative in such systems. Richard et al. (2007) have measured the H/D isotopic fractionation factor (