Sustainable supercritical fluid recycling of retired wind turbine blades: High-purity glass fibers and bisphenol A recovery.

The decommissioning of retired wind turbine blades (RWTB) results in a significant accumulation of composite waste, with over 4.3 × 107 tons projected by 2050, highlighting the urgent need for efficient recycling solutions. This study investigates supercritical ethanol depolymerization (SCED) as a method for recovering high-purity glass fibers and bisphenol A (BPA) monomers. The effects of reaction temperature, residence time, and solid-to-liquid mass ratio (S/L) are systematically evaluated, with temperature identified as a critical factor for resin degradation. GC-MS analysis confirms that BPA and phenol are the dominant liquid products. Under optimal conditions (280 °C, 60 min, S/L ratio 1:4), resin degradation achieves 97.4 %, BPA yield reaches 8.3 wt%, and the recycled glass fibers exhibit a remarkable tensile strength of 1859.87 MPa. Using recycled ethanol maintains resin degradation above 95 %, with only a slight reduction in BPA yield. The degradation pathways suggest that SCED not only recovers high-strength fibers but also facilitates hydride transfer within the epoxy resin matrix. Furthermore, the recycled glass fibers are effectively upcycled to enhance the production of aerated concrete bricks (ACB) from incineration ash, boosting their compressive strength by 121 %. In summary, SCED represents a promising technology for the high-value treatment of RWTB.