Work

Wettability based separation of ionomer-containing ultrafine particles for PEM water electrolyzer recycling

Year: 2025

Type: article

Abstract: As green hydrogen production via proton exchange membrane water electrolyzers (PEMELs) continues to scale up, the development of effective recycling processes for end-of-life components is becoming increasingly important. In PEMELs, ultrafine catalyst particles exhibit significant differences in hydrophobicity, which serve as a basis for selective separation. In this study, two separation techniques based on hydrophobicity differences (liquid–liquid particle separation and emulsion-based froth flotation) were proposed for particle recovery. Since catalyst inks contain amphiphilic ionomers as binders in addition to the particles, their influence on wettability-based separation was investigated. To clarify this effect, we investigated the physicochemical characteristics of ionomer-coated particles. Key parameters such as particle size, surface area (BET), and zeta potential were measured, and their impact on wettability was assessed. The results show that ionomer adsorption leads to a notable reduction in the hydrophobicity contrast, thereby hindering their selective separation. To address this issue, dispersant was introduced to both separation processes. This addition improved the recovery performance, under conditions where the hydrophobicity difference was reduced. Although the addition of dispersants improved the recovery performance, the separation efficiency remained lower than that observed under ionomer-free conditions. The findings highlight the complex interactions between particles, ionomers, and reagents in dispersion systems. Further investigation into these interactions is necessary to develop more robust and scalable recycling strategies. A deeper understanding of the physicochemical mechanisms will provide valuable insight into the design of selective separation processes for catalyst recovery in PEMEL systems.

Source: JCIS Open

DOI: 10.1016/j.jciso.2025.100161

Authors: Sohyun Ahn, Siddhi Kulkarni, Suvarna Patil, Urs A. Peuker, Martin Rudolph

Institutions: Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, TU Bergakademie Freiberg

Language: English

Topic: Minerals Flotation and Separation Techniques

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation, Affordable and clean energy

Open Access status: gold

Estimated APC paid: $1,590