Measurement of the pure dissolution rate constant of a mineral in water

TL;DR

This paper introduces a holographic interferometry method to accurately measure the pure surface reaction rate constant of mineral dissolution in water, free from mass transport effects, providing new insights into mineral dissolution rates.

Contribution

The paper presents a novel holographic interferometry technique to measure mineral dissolution rate constants without mass transport influence, previously unmeasured for gypsum.

Findings

Pure dissolution rate constant for gypsum is much smaller than expected.

Method provides reliable rate constants for dissolution model validation.

Clues to explain dissolution rate discrepancies between calcite and aragonite.

Abstract

We present here a methodology, using holographic interferometry, enabling to measure the pure surface reaction rate constant of the dissolution of a mineral in water, unambiguously free from the influence of mass transport. We use that technique to access to this value for gypsum and we demonstrate that it was never measured before but could be deduced a posteriori from the literature results if hydrodynamics is taken into account with accuracy. It is found to be much smaller than expected. This method enables to provide reliable rate constants for the test of dissolution models and the interpretation of in situ measurements, and gives clues to explain the inconsistency between dissolution rates of calcite and aragonite, for instance, in the literature.