Recovery of High Purity Gadolinium and Yttrium Oxides from Ceramic Waste

Abstract Gadolinium and yttrium oxides are critical materials for thermal barrier ceramics used in automotive, aerospace, and defense applications. This study presents the first ligand-assisted displacement (LAD) chromatography methods for recovering gadolinium and yttrium oxides from ceramic waste. A model-driven design method based on intrinsic (scale-independent) parameters and dimensionless correlations enabled predictive process design using minimal experimental data. The first innovation was the use of yttrium, a high-affinity feed component, as the pre-saturant. This self-replenishing strategy eliminated the need for an external pre-saturant for continuous operation, creating a self-sustaining process. The second innovation was the development of a one-zone recycling process to produce 99.9% pure oxides with 99% yield, while maintaining high productivity. The designs were validated by rate model simulations and seven chromatography experiments, covering a wide range of feed compositions, column sizes, and operating configurations. Both the one-zone recycling and two-zone cascade achieved 1.9 times higher productivity than a single pass process. The one-zone recycling is operationally simpler than the two-zone cascade, making it more attractive for industrial implementation. Furthermore, eliminating sodium ions from the leachate doubled the process productivity. These results established LAD chromatography as an efficient scalable platform for recovering high-purity rare-earth oxides from ceramic waste.