Showing 121 results for Author: Andrew G. Stack
Sep, 2026
Journal
The effects of individual component salts on MgO hydration and subsequent carbonation have not been systematically investigated despite the increase in utilization of seawater and other brines in the production of MgO-containing next-generation cements, fire retardants, and sorbents for CO2. Here, we present a study of MgO hydration in the presence of individual saltwater…
May, 2026
Journal
Ion sorption extent and mechanism depend in part on the mineral surface termination, which can be highly complex. Variations in surface termination, particularly with defect density and surface roughness, influence mineral reactivity towards solutes. In this work, we investigate the adsorption of a rubidium cation at pristine and defect quartz (101) surface sites using wel…
May, 2026
Journal
Ion sorption extent and mechanism depend in part on the mineral surface termination, which can be highly complex. Variations in surface functional groups, particularly with defect density and surface roughness, influence mineral reactivity towards solutes. In this work, we investigate the adsorption of a rubidium cation (Rb+) at pristine and defect quartz (101) surface sit…
Apr, 2026
Journal
Brucite [Mg(OH)2] is a promising sorbent for carbon dioxide removal (CDR) due to its availability and low calcination temperatures. However, natural and synthetic brucites tend to contain metal impurities, such as iron or manganese, and how these impurities affect the interfacial chemical reactivity is uncertain. Here, the impact of low concentrations of iron and manganese…
Mar, 2026
Journal
Recovery of magnesium from brines can potentially be used to source MgO (periclase) as a CO2 sorbent or for Mg-based cements. However, it is not clear how common impurities in brines, such as lithium, affect the resulting MgO reactivity. To test the effect of lithium incorporation on MgO reactivity for hydration and carbonation, we combined computational simulations with e…
Feb, 2026
Journal
Structural defects and lattice strain are intrinsic to many crystalline materials, yet their roles in controlling chemical reaction mechanisms and directing crystallization pathways remain poorly understood. Here, we revealed the three-dimensional evolution of strain and dislocation defects at the nanoscale during the growth of heterogeneously nucleated barite (BaSO4) and…
Nov, 2025
Journal
Magnesium oxide (MgO) is considered as a potential sorbent for direct air capture of carbon dioxide in a looping process. Previous research on mineral looping for carbon capture from flue gas using MgO has shown deactivation of the sorbent with repeated cycles but repeated cycling for carbonation at ambient conditions has not been yet investigated. Here, we tested three cy…
Sep, 2025
Journal
Catalyst size, morphology, and crystal structure play crucial roles in determining the activity and selectivity of electrochemical CO2 reduction reactions, which are known to change during the reaction process. A comprehensive understanding of how, when, and why these parameters evolve under operational conditions is essential for developing stable, efficient, and selectiv…
Aug, 2025
Journal
The hydroxylation of periclase (MgO) to brucite (Mg(OH)2) is thought to be an important intermediate step when using MgO to capture CO2 from the atmosphere. However, the mechanism of hydroxylation of MgO to form Mg(OH)2 is poorly understood. In this work, we used atomic-scale density functional tight binding simulations coupled with the metadynamics rare event method to an…
Aug, 2025
Journal
Volume-increasing replacement reactions can lead either to fracturing of the parent phase or to the formation of cohesive layers that passivate further reaction, but the factors that drive one outcome or the other are not understood. In this experimental study, we investigated the volume-increasing replacement of carbonate rocks (consisting of CaCO3 and CaMg(CO3)2) of diff…
Apr, 2025
Journal
Experimental measurements of the heterogeneous nucleation rate rely on counting the number of nuclei with time. However, the size of a thermodynamically stable nucleus is often a few nanometers in diameter and is below the resolution of most (in situ) measurement techniques that provide a statistically valid sample. Due to the finite resolution of the instruments and analy…
Mar, 2025
Journal
Despite extensive research on MgO’s reactivity in the presence of CO2 under various conditions, little is known about whether impurities incorporated into the solid, such as iron, enhance or impede hydroxylation and carbonation reactions. The purity of the MgO required for the successful implementation of MgO looping as a direct air capture technology affects the deploymen…