Reaction rates are usually measured in the laboratory with a well-mixed condition induced by a stirrer or rotating disk. These rates are often several orders of magnitude higher than those occurring in nature, based on field measurements. The laboratory-field rate discrepancy has been a longstanding topic in the field of geochemistry. One of the factors that were ignored is the limiting effect of transport (advection and diffusion). We improved upon the existing theories to study the evolution of transport-controlled dissolution rate as the conduits (holes and fractures) enlarge. We found that the transport-controlled dissolution rate stays constant in an enlarging hole, while decreases in an enlarging fracture. Here is more on transport-controlled dissolution.
Dissolution kinetics in geosystems
We developed an effluent chemistry monitoring system (ECMS) that is integrated into the top end cap of a triaxial system. This system measures the electric conductivity and temperature of the outflow from the specimen (effluent) during flow tests. This avoids the time-consuming and costly process of effluent sampling. It also eliminates the errors caused by human handling and provides high time-resolution continuous measurement. This system is calibrated to directly monitor the evolution of overall reaction rates in the solid-fluid system under triaxial stress conditions. Here is more on ECMS.
3-D wormhole formation
Underground fluid flow and chemical reactions often result in wormholes, which are channels that look like tree roots. They significantly increase the permeability of the porous media by creating highways for the flow. Wormhole formation is relevant in many natural and industrial processes, including the formation of underground caves, CO2 sequestration and enhanced oil recovery. Our experimental study on wormholes in 3D porous media found a power-law scaling of wormhole lengths with a greater exponent than those in 2D cases. We also improved upon existing models to better predict the relation between wormhole length and permeability. Here is more on wormhole formations.