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Excerpt from the Proceedings of the COMSOL Conference 2025 Amsterdam REFERENCES Gas-liquid system in the GDEx process for PGMs recovery. María I. León, Savitha Thayumanasundaram VITO - Vlaamse Instelling voor Technologisch Onderzoek Boeretang 200, 2400 Mol, Belgium GDEx was modeled as a gas–liquid system where CO₂ is introduced through a porous electrode into an H₂O–NaCl solution, generating H₂ and CO in situ to drive PGMs precipitation. A laminar two-phase flow with level-set interface and species transport was simulated and validated against experimental data on dissolved H₂ and ionic species under varying flow rates and current densities. 𝜕𝛟 𝜕𝑡 + 𝒖 ∙ ∇𝛟 = 𝛾∇ ∙ 𝜀∇𝛟 − 𝛟 1 − 𝛟 ∇𝛟 ∇𝛟 FIREFLY Project Website: https://www.firefly-project.eu/ O. Martinez-Mora, G. Pozo, L.F. Leon-Fernandez, et al., Synthesis of platinum group metal nanoparticles assisted by CO₂ reduction and H₂ cogeneration at gas-diffusion electrodes, RSC Sustain. 1 (2023) 454. https://doi.org/10.1039/d3su00046j Understanding gas–liquid mass transfer barriers unlocks better recovery of elemental PGMs by fine-tuning key transfer parameters. Catalysts are essential for efficient chemical processes, but platinum group metals (PGMs) are critical raw materials with supply risks. The FIREFLY project aims to develop sustainable technologies to recover PGMs from industrial waste using integrated physical, chemical, and electrochemical methods. This work focuses on Gas-Diffusion Electrocrystallization (GDEx), which precipitates PGMs by generating H₂ and CO in situ. The study combines modeling of gas–liquid interactions and bubble dynamics with experimental validation to optimize recovery and improve circularity in catalyst-based industries. Introduction & Goals Methodology FIGURE 1. Schematic representation of the GDEx system operating in recirculation mode. •Higher current density (J) → increased H₂ generation and higher dissolved H₂ concentration. •Increased liquid flow rate → decreased dissolved H₂ due to reduced gas–liquid contact time. •PGMs precipitation trends matched simulations under varying J and gas flow rate (Q) conditions. Results FIGURE 2. Gas–liquid interactions inside the GDEx electrochemical cell. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HADEA). Neither the European Union nor the granting authority can be held responsible for them. This research was funded by the European Union’s Horizon Europe research and innovation program under grant agreement No. 101091715.
