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Recycling of Li-ion batteries (LiBs) for metal recovery has gained increasing attention in recent years. Batteries contain per- and polyfluoroalkyl substances (PFAS), however, their behaviour during battery recycling is still not well understood. This study aims to (i) characterise the presence of PFAS in LiBs black mass collected from various recycling factories in Australia, and (ii) investigate the fate of PFAS during the metal recovery process. The concentration of bis-perfluoromethanesulfonimide (bis-FMeSI) (C2) in the black mass was up to 51,000 µg kg−1. Other emerging and legacy PFAS were present, with concentrations varying from 0.1 to100 µg kg−1. The complementary analysis results of extractable organically bound fluorine and Fluorine K-edge X-ray adsorption near-edge structure indicates that the LiBs black mass mainly consists of bis-FMeSI (C2) and LiPF6 as the main PFAS analytes (40 – 80% fluorine equivalent), however other unknown PFAS may also be present. The long-chain PFAS are more difficult to leach compared to the short-chain PFAS. H2SO4 leaches 58% bis-FMeSI which is the highest compared to HNO3 (51%) and HCl (40.4%). During the precipitation stage, adding H2O2 to the H2SO4 (5% v/v) leaching agent increased bis-FMeSI adsorption onto metal precipitates by 40%. Using PiFM analysis, PFAS are found predominantly present as surface-associated species within binder- and carbon-rich domains, and the leaching mechanism is strongly attributable to the disruption of these surface-accessible phases. This work constructs the first baseline for the relevant research about the trade-off between metal recovery and PFAS pollutants in the LiBs recycling process.
Per- and polyfluoroalkyl substances (PFAS) are well-known as “forever chemicals” and persistent pollutants released by different anthropogenic sources. The potential release of PFAS from accumulating electronic waste and lithium-ion battery (LIB) recycling activities has gained increasing attention in the past years. This creates a need for analytical methods tailored for the determination of PFAS out of environmental matrices related to the named activities or directly out of the concerned materials. In this work, analytical strategies for the monitoring of PFAS in LIB recycling materials were explored for a group of legacy perfluoro sulfonic- and carbonic acids (PFSA and PFCA) and of fluorinated sulfonylimides suspected to be LIB electrolyte ingredients. These analytical strategies comprehend PFAS target approaches with a herein optimized liquid chromatography tandem mass spectrometry (LC–MS/MS) method equipped with a HILIC (hydrophilic interaction liquid chromatography) column in combination with the TOP (total oxidizable precursor) assay and an adapted sample preparation method for high-matrix LIB recycling materials. The validated target method was applied to a set of LIB recycling materials: end-of-life batteries, black masses from hydrometallurgical recycling, and gas absorption solutions from thermal treatment of black masses as part of the recycling procedure. Investigation results show that the LIB industry can be connected to the release of both “LIB”-PFAS, such as the target sulfonylimides, and “already-legacy” PFAS, like the PFSA and PFCA. Especially, the presence of trifluoroacetic acid (TFA) as an emerging pollutant in every investigated LIB material type underlines the threat of PFAS emissions from LIB waste and recycling activities.
