3D printing of reactive porous media to enhance understanding of porosity-permeability evolution

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Geochemical reactions play an important role in natural and engineered systems, occurring as part of natural weathering processes, at contaminated subsurface and surface sites, and in geologic CO2 sequestration, radioactive waste disposal, and other engineered subsurface systems. Understanding the impact of these reactions on flow and transport is critical to assessing long-term evolution of these systems, including risks and adverse environmental impacts. However, current understanding of the impact of mineral dissolution and precipitation reactions on porous media properties is limited. These systems are difficult to evaluate with laboratory experiments because natural samples are highly heterogenous and different results can be obtained for even replicate experiments with samples from the same location. In this work, the use of 3D printing to create replicable, reactive porous media samples will be explored and used to enhance understanding of reactions and permeability evolution in porous media. Observations will be leveraged to generate new porosity-permeability relationships with improved predictive capabilities. Advancements in understanding from this work will generate knowledge needed to improve engineering design of subsurface energy systems, enhance understanding of contaminant fate and transport in subsurface systems, and improve understanding of near surface weathering processes. This work will encompass a range of broader impacts ranging from K-12 outreach, graduate student education, and enhancing diversity in STEM students in addition to increasing understanding of transport and reactions in natural systems. Undergraduate and graduate students from underrepresented groups will be recruited for this project and included in outreach activities aimed to enhance interest and diversity in STEM fields.The goal of this work is to enhance understanding of mineral dissolution and precipitation reactions and impacts on porosity and permeability in porous media. The highly heterogenous nature of porous media complicates experimental efforts and limits predictive capabilities. Critically, this proposal will utilize 3D printing to fabricate replicate reactive porous media that maintain the physical heterogeneities of real porous media to enhance understanding of the impact of variations in porous media structures and the distribution of mineral reactions on where mineral reactions occur and, consequently, changes in porosity and permeability. The approach will be to create a series of 3D printed “reactive” porous media and carry out replicate laboratory mineral dissolution and precipitation experiments on these samples, characterizing permeability evolution and using 3D imaging to identify the time lapsed evolution of porosity. Experimental observations will be leveraged to develop new macroscopic porosity-permeability relationships with improved predictive capabilities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.