『Abstract
The kinetics of glauconite dissolution have been determined in
the pH range 2-10 (T = 25℃) using flow-batch reactor experiments.
Besides the kinetic characteristics, the structural and textural
aspects which could influence its long-term reactivity have also
been characterized by means of X-ray diffraction (XRD), high-resolution
transmission electron microscopy (HRTEM), scanning electron microscopy
(SEM) and BET surface area measurements. The results from these
analyses showed that glauconite follows a dual dissolution pathway
which is pH-dependent, being more stable at neutral or slightly
alkaline pH values. Under acidic conditions, glauconite is slightly
more soluble than other ubiquitous silicates present in the marine
sediments. The dissolution mechanism is incongruent at very acid
pH values and tends to be congruent for intermediate and neutral
ones. In addition, the results from the structural analyses suggest
that the dissolution is a two-step process: the first one involves
the disorder of the octahedral and tetrahedral layers, probably
following a turbostratic mechanism which is evident in the XRD
spectra as selective broadening of several reflections. In the
second step, the dissolution of the cations from interlayer positions
takes place and leads to the formation of an amorphous residue
which acts as a passivating layer and reduces the reactive surface
considerably. The influence of these aspects on CO2
capture via carbonation reactions is discussed.』
Introduction
Materials and methods
Results and discussion
Kinetics of glauconite dissolution
Mesostructural and microstructural modifications induced by the
dissolution process
Conclusions
References