Tomographic analysis of reactive flow induced pore structure changes in column experiments

We utilize synchrotron X-ray computed micro-tomography to capture and quantify snapshots in time of dissolution and secondary precipitation in the microstructure of Hanford sediments exposed to simulated caustic waste in flow-column experiments. The experiment is complicated somewhat as logistics dictated that the column spent significant amounts of time in a sealed state (acting as a batch reactor). Changes accompanying a net reduction in porosity of 4% were quantified including: (1) a 25% net decrease in pores resulting from a 38% loss in the number of pores <10-4mm3 in volume and a 13% increase in the number of pores of larger size; and (2) a 38% decrease in the number of throats. The loss of throats resulted in decreased coordination number for pores of all sizes and significant reduction in the number of pore pathways.