The Calcitic Marble/Water Interface: Kinetics of Dissolution and Inhibition with Potential Implications in Stone Conservation

Abstract

The dissolution of powdered Carrara marble was investigated in the absence and in the presence of (1-hydroxyethylidene)-1,1-diphosphonic acid (HEDP) at conditions of constant undersaturation at pH 8.25. The dependence of the rates of dissolution on the relative undersaturation suggested a surface diffusion controlled mechanism. According to this mechanistic information, the interaction of HEDP with calcitic Carrara marble was investigated. Two types of interaction of the HEDP with the marble suface were studied: preadsorption and addition of HEDP in the undersaturated solutions (1 μM to 1 mM). In both cases the rates of dissolution were drastically reduced depending on the concentration of the organophosphorus compound on the marble surface or in the undersaturated solutions. The rate reduction was attributed to the poisoning of the active dissolution sites through the uptake of HEDP on the calcite crystallites of the Carrara marble. The HEDP uptake by marble was measured quantitatively. The zeta potenti...