(607e) Obtaining Structure-Function Insight from High-Throughput Membrane Characterization

Creating systems and techniques capable of reducing the time, energy, and resources needed to characterize the transport properties of polymer membranes can help increase the rate of material and process development. For example, improved characterization techniques need to address the knowledge gaps related to the interfacial processes that govern solute-solute selectivity and capture the performance of membranes in complex multi-component feed streams. To address this need, a diafiltration apparatus is developed to rapidly characterize membrane performance over a broad range of feed solution compositions. By systematically dosing a high concentration diafiltrate into the stirred cell, a predetermined change in the retentate concentration can be achieved and materials can be characterized up to 12 times faster when compared to a traditional campaign of filtration experiments. The volume and reproducibility of the generated data enables data analytics to inform experimental design. For instance, using the Fischer information matrix, it was determined that parameter precision would increase by monitoring the real time retentate concentration. As such, an inline conductivity probe was incorporated in the experimental apparatus. The technique is validated by characterizing two commercial membranes (i.e., neutral NF90 membranes, charged NF270 membrane). Two primary conclusions result. (1) Incorporating the appropriate governing phenomena identifies a single set of self-consistent transport parameters. (2) Diafiltration experiments can establish relationships between membrane parameters (e.g., solute permeability coefficient) and system properties (e.g., rejection, bulk retentate concentration). We conclude by illustrating how diafiltration experiments can generate structure-function insight by comparing data obtained from functionalized copolymer membranes. Specifically, experiments capture changes to macroscopic system properties (i.e., rejection) that result from systematic modifications to material nanostructure and chemistry (e.g., changes in diamine tether lengths). As such diafiltration experiments can both accelerate material design and, coupled with data analytics, provide insight on governing transport mechanisms.