Room Temperature Magnesite Precipitation

Abstract

Magnesite (MgCO3) is one of the most stable sinks for carbon dioxide (CO2) and is therefore of great interest for long-term carbon storage. Although magnesite is the thermodynamically stable form of magnesium carbonate, the kinetic inhibition of low-temperature precipitation has hindered the development of carbon sequestration strategies that can be economically conducted under ambient temperature. Here, we document the precipitation of magnesite from waters (magnesite saturation index = 1.45) in batch reactors at room temperature with the aid of carboxylated polystyrene microspheres over the course of 70 days. Microspheres provide surfaces with a high density of carboxyl groups that act to bind and dehydrate Mg2+ ions in solution, thereby minimizing the kinetic barrier and facilitating magnesite formation. Magnesite crystals are observed on sphere surfaces and their organic matrixes. Mineral identification was confirmed by X-ray diffraction and selected area electron diffraction of a thin section obtaine...