Structure of Silica Polymers and Reaction Mechanism for Formation of Silica-Rich Precipitated Phases in Direct Aqueous Carbon Mineralization

Abstract

This research aims to provide insight into the structure and reaction mechanism of silica-rich phases formed as byproducts in direct aqueous carbonation of heat-activated lizardite. In undertaking this work, we employed analytical techniques such as thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), 29Si solid-state nuclear magnetic resonance (29Si SS NMR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to characterize carbonation products and to understand the mechanism of formation and the structure of silica-rich byproducts. Thermodynamic analysis predicts the formation of magnesite and amorphous silica in the process of direct aqueous carbonation of heat-activated lizardite under the experimental conditions studied. Characterization of carbonat...