Molecular-to-Systems Scale Design of Diafiltration Cascades for Improved Solute Recovery and Purity

Sustainable energy solutions and electrification are driving increased demand for critical minerals; albeit the existing technologies are at odds with the sustainability goals driving increased demand for critical minerals. The small footprint and modular nature of membrane technologies position them well to substitute current technologies as they are able to address the declining concentrations in ores and brines, the variable feed concentrations encountered in recycling, and the environmental issues associated with current separation processes. The success of implementing membranes into these processes’ hinges on the exploration and rapid development of new and existing materials over industrially diverse feed conditions.
In this context, this dissertation establishes new characterization techniques, which address knowledge gaps related to the interfacial processes that govern solute-solute selectivity and the performance of membranes in complex multi-component feeds streams, to advance membrane processes. Guided by the tools of data science, a diafiltration apparatus is developed to inform material and process design by rapidly characterizing membrane performance over a broad range of feed solution compositions. The apparatus is built from the ground up and validated with commercial membranes. One key component of the apparatus is the automation, implemented throughout the data collection and processing, that will become a critical piece towards developing self-driving laboratories. This dissertation subsequently extends the utility of the diafiltration apparatus to systematically characterize the effect of complex feed compositions on solute transport. The characterization of solute transport coupled with the systems scale design of diafiltration cascades highlights opportunities in which membranes can transform the field of separations.