Biogeochemical Gradients and Radionuclide Transport (BIGRAD) 

Mineral transformation using a physical scale model

Objective

  • To monitor changes in pH and aqueous chemistry of an alkali plume in a 2D model sandstone aquifer.
  • To evaluate mineralogical transformations at the pore-scale in the host sandstone arising from contact with an alkaline plume, using optical and electron microscopy.
  • To evaluate kinetic and thermodynamic parameters for aqueous and mineral transformations.

Experimental setup

                  2D_flow_cell_setup

          Flow_cell_irradiated

The flow cell is a perspex flow chamber with quartz front plate packed with quartz sand. The configuration shown here represents current PhD experiments and includes a zero-valent iron reactive barrier for the reductive precipitation of U(VI) from a model groundwater plume. In the BIGRAD project, the cell will be fed from top with solutions of controlled radionuclide concentration, O2 and pH that reflect the alkali plume environment. Changes on the concentration gradient are imaged when the cell is irradiated with UV light from the back and recorded with a digital camera. The cell will be open post exposure and samples will be analysed by electron microscopy to study the effect of the alkaline plume on the mineral composition.