Closed-loop recovery under mild conditions of end-life wind turbine blade via synergy of responsive deep eutectic solvent-ZnCl2

The decommissioning tide of wind turbines is creating millions of tons of solid waste. The fibre-reinforced polymer composites (FRPCs) in turbine blades are heavily crosslinked and chemically inert: their efficient and environmentally friendly recycling is the major challenge but crucial for achieving a circular economy. Although high-purity fibres can be recovered using chemical solvent degradation methods, current state-of-the-art processes suffer from harsh reaction conditions, toxic gas emissions during treatment, difficulty in efficiently separating resin degradation products (small molecules), and non-recyclable solvents. In this article, we describe and demonstrate a heterogeneous catalysis degradation system based on the synergic action of responsive deep eutectic solvent (RDES) and transition metal compound (ZnCl2). This system achieves (i) targeted cleavage of C-O bonds under mild conditions, achieving 100% degradation of FRPCs at 150 °C and atmospheric pressure within 18 h with an consumption of only 0.69 kWh, (ii) the preservation of high-value epoxy networks (Mn: 780–1200 g/mol) and high-performance glass fibres, and (iii), thanks to the switchable nature of RDES, full and simple recovery of RDES, catalyst, degradation products, and fibres. This green, efficient, and recyclable RDES-ZnCl2 synergistic degradation system provides new ideas for sustainable large-scale recycling of FRPCs.