FABRICATION OF POLYVINYLIDENE FLUORIDE-BASED POLYMER INCLUSION MEMBRANES FOR THE SELECTIVE EXTRACTION OF RARE EARTH ELEMENTS FROM ELECTRONIC WASTE LEACHATES

Abstract

Rare earth elements (REEs) are important materials of modern technologies, but these elements are difficult to obtain from conventional mining due to both environmental and geopolitical reasons, which has led to the exploration of secondary sources such as e-waste. Herein, we report on the early-stage development and evaluation of PIMs, prepared using PVDF, with the aim of extracting REEs. Membranes were fabricated using three different solvents, namely dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and dimethylformamide (DMF), using the NIPS technique and then quenched with either water or air. The membranes were characterized by analyzing the mechanical strength, thickness, and morphology, and the results were analyzed to determine the influence of fabrication conditions on the structural properties relevant to REE transport. The results indicated that water-quenched membranes were generally thicker than air-quenched ones, whereas membranes made with NMP had the highest tensile strength, at approximately 4.3 MPa. Scanning Electron Microscopy (SEM) images of the membranes confirmed that those fabricated with DMAc had the most porous structure, followed by DMF and NMP, which is consistent with the lower swelling index (40.68%) and higher water absorption (8.94%) of these membranes, allowing extractants to diffuse more readily through the membrane. Overall, these results demonstrate that the choice of solvent and quenching method is critical to the determination of the membrane strength and porosity, two properties that are critical to the efficient extraction of REEs, and future work will incorporate ionic liquid extractants and assess the transport of REEs from e-waste leachates.