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Abstract Carbon mineralization in humidified carbon dioxide offers a promising route to mitigate anthropogenic emissions in a world stressed by water security. Despite its technological importance, our understanding of carbonation in water-poor environments lags, as traditional dissolution-precipitation pathways struggle to explain the adsorbed water nanofilm-mediated reactivity. Here, we utilizein operandoX-ray diffraction (XRD) and advanced molecular simulations to investigate nanoconfined reactions driving forsterite carbonation, the magnesium-rich olivine. By examining magnesium ion dissolution and transport in atomistic simulations of the forsterite-water-carbon dioxide interface and comparing these with thein operandoXRD activation energies, we identify both processes as rate-limiting at saturation. Our simulations reveal a mechanistic view of interfacial carbonation, where dissolution and precipitation are mediated by anomalous quasi two-dimensional diffusion. The transport process involves intermittent diffusive hopping in the desorbed state, separated by crawling events that are spatially short but temporally long. This understanding transcends carbon mineralization, with implications for understanding the transport of contaminants in geosystems, the design of multifunctional materials, water desalination, and molecular recognition systems. 

Urbanization and climate change are contributing to severe flooding globally, damaging infrastructure, disrupting economies, and undermining human well-being. Approaches to make cities more resilient to floods are emerging, notably with the design of flood-resilient structures, but relatively little is known about the role of urban form and its complexity in the concentration of flooding. We leverage statistical mechanics to reduce the complexity of urban flooding and develop a mean-flow theory that relates flood hazards to urban form characterized by the ground slope, urban porosity, and the Mermin order parameter which measures symmetry in building arrangements. The mean-flow theory presents a dimensionless flood depth that scales linearly with the urban porosity and the order parameter, with different scaling for disordered square- and hexagon-like forms. A universal scaling is obtained by introducing an effective mean chord length representative of the unobstructed downslope travel distance for flood water, yielding an analytical model for neighborhood-scale flood hazards globally. The proposed mean-flow theory is applied to probe city-to-city variations in flood hazards, and shows promising results linking recorded flood losses to urban form and observed rainfall extremes. 

Understanding the mechanism that controls cement hydration and its stages is a long-standing challenge. Over a decade ago, the mineral dissolution theory was adopted from geochemistry to explain the hydration rate evolution of alite. The theory is not fully accepted by the community and deserves further investigation. In this work, we apply Kinetic Monte Carlo (KMC) simulations with the mineral dissolution theory as a conceptual framework to investigate and discuss alite dissolution. We build a Kossel crystal model system and parameterize the dissolution activation energies and frequencies based on experimental data. The resulting KMC model is capable of reproducing the dissolution rate and activation energies as a function of the dissolution free energy. The simulations indicate that mineral dissolution theory easily explains the induction and acceleration stages due to a continuous increase of the reactive area as the etch pits open. However, the deceleration stage is hardly reconcilable with the mechanism suggested in the literature, i.e. dislocation coalescence. Still, within the mineral dissolution theory umbrella, we propose and discuss an alternative mechanism based on dislocation exhaustion.