NSF REU at K-State: Interactions of Matter, Light and Learning
The K-State REU program offers summer fellowships to do world-class research in our friendly physics department in the scenic Flinthills. We are funded by the National Science Foundation.
Soft Condensed Matter and Biophysics
Crystal Growth Rate Studies in Galvanically Driven Systems (Experimental)
Email: bret.flanders@phys.ksu.edu
The build-up of CO2 in the atmosphere underlies the greenhouse effect and oceanic acidification. Of our planet’s several natural sinks for excess CO2, carbonate mineralization stands out as an essentially permanent means of locking up carbon. Our own (local) Flint Hills is one such stable deposit; the Dolomites is an obvious other—dolomite is CaMg(CO3)2. All told there is 40 times more carbon buried in Earth’s crust than there is in the atmosphere. Unfortunately, CO2 mineralization slow. The planet absorbs ~350 GT/yr (giga-tons per year), but only ~0.1 GT/yr gets mineralized. Major engineering efforts—CarbFix in Iceland and Heirloom in California—aim to speed up carbon capture and mineralization by essentially hydrothermal means—pumping high pressure CO2 streams into porous, mineral-rich rock. This project investigates a little-studied aspect of carbonate mineralization—the effectiveness of galvanic couples in the mineralization process. It is known that one can rapidly deposit CaCO3 by shifting the pH of a solution during electro-precipitation, where a voltage between the substrate and a counter-electrode induces OH- production. The same process can be done using dissimilar metals (i.e. galvanic couples) to produce the voltage. As dissimilar metals are naturally present in mineral-rich soils, it is likely that galvanic couples become established when soils get wet and that these couples electro-precipitate carbonaceous salts from the soil-based solutions.
The goal of this study is to measure CaCO3 growth rates in galvanically driven solutions as a function of galvanic couple-type in order to quantify the control-parameters for these systems. A typical experiment consists of using an quartz crystal microbalance (QCM) coupled to a long working distance optical microscope to simultaneously observe seeding and measure mass during the nucleation phase of CaCO3 growth. Subsequently, we transfer the seeded plates to solutions with different dissimilar metal-pairs and determine the growth rates of calcite as a function of galvanic couple-type. Challenges include overcoming mass-transport limitations on the growth rates. A strategy that we will refine is to pulse the electrical continuity of the galvanic couple in an on-off manner, where we measure mass during the on-periods and stir the solution during the off-periods. We have already determined that the normalized growth rates of galvanically driven systems are up to 20 times faster than the baseline rate associated with the bulk supersaturation-level. Other directions may address the feasibility of galvanically driving calcite formation in the field, building on preliminary evidence that galvanic current through soil can induce carbonate-mineralization. Work on this project would involve working with experimental equipment, calibration and assembly, control-programming in Python, data-analysis, and learning relevant crystal growth and aquatic chemistry theory.
Modeling Biological Phase Separation (Theoretical)
Email: schmit@phys.ksu.edu
Research over the last 15 years has shown that many structures in biological cells are formed by the spontaneous condensation of biomolecules (proteins and nucleic acids). This condensation process strongly resembles a phase transition and has opened many questions about the physics that controls condensation. This project will look at the statistical physics of these "condensates" to identify the factors that bring the molecules together and limit the compaction of the resulting structures.