The widespread use of phones, electric vehicles and other electronic devices, has led to increased demands for critical materials and the generation of large amounts of e-waste. In 2023, it was estimated that approximately 5 billion cells phones would be thrown away worldwide. Recycling devices offers a promising opportunity to supplement primary raw material sources. Currently, in order to recycle batteries, source materials must first be collected and disassembled. Subsequently, the battery is ground, and the desired ions are leached out of the material using strong acids. Ions are separated from one another using liquid-liquid extraction, a technique which uses large amounts of solvents and generates secondary waste. An alternative, more sustainable method is the use of membranes. Membranes separate solutes by modulating the strength of the interaction, and diffusion through the polymer network. As such, one avenue to separate ions is by introducing selective interactions: for instance, metal ligand coordination bonds.
The purpose of this study is to develop membranes that can be functionalized with ion-specific ligands to remove ions from a multicomponent feed stream. Using thin film membranes, we explored a range of conditions under which a reactive moiety could be functionalized (PFPA). We find that primary amines are not sensitive to the solvent as long as they are soluble. Imidazoles were chosen as a ligand due to their selectivity for copper. Propargylamine was also chosen due its potential in thiol click chemistry. Additionally, a stereolithography (SLA) 3D printer was utilized to print membranes for high throughput permeability testing. UV light experiments were conducted to determine the minimum energy required to polymerize our resin, and the 3D printer exposure settings were adjusted accordingly. All 3D prints failed to polymerize correctly, indicating a fundamental difference between SLA and DLP printing. Future studies should focus on further testing the analyzing of the 3D printer and measuring the conductivity of the permeate to evaluate permeability.