From waste to resources: sample preparation approaches in combination with GC×GC-TOFMS for the characterization of wind turbine blade recycling products

The growth of renewable energy infrastructure highlights the urgent need for sustainable solutions to manage end-of-life materials, including wind turbine blades (WTBs). These composite materials present significant challenges in recycling due to their complex heterogeneous structure and varied chemical composition. In this study, two recycling pathways — solvolysis and pyrolysis — were explored, each supported by a dedicated sample preparation strategy prior to detailed molecular characterization of the resulting products. For solvolysis products, microwave-assisted extraction (MAE) was carried out using a hexane–methanol mixture (10:3 ratio), followed by water addition (2.5 ratio) and centrifugation to achieve phase separation. Pyrolysis products, in parallel, were subjected to solid-phase extraction (SPE), which allowed the isolation of distinct chemical families from the complex mixture. The MAE extracts and SPE fractions obtained were subsequently analyzed using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). Compound identification was based on mass spectral electron ionization (EI) database matching at 70 eV (≥800/1000) and the Linear Retention Index (LRI) (±20 range). The location of the investigated molecules on the 2D-GC plane was also considered. In total, around 120 compounds belonging to different chemical classes such as hydrocarbons, aromatics, and heteroatom-containing molecules were identified in the solvolysis products. Regarding the SPE fractions of pyrolysis-derived products, the use of a normal-phase sorbent with eluting solvents of increasing polarity allowed for the separation of hydrocarbon-rich fraction from one enriched in oxygen- and nitrogen-containing compounds.