Effect of Process Parameters on Plasma-Enhanced Solvolysis of CFRPs

The current study investigates plasma-assisted chemical recycling as an innovative approach to recover valuable carbon fibers from composite waste while minimizing environmental impact. Nitrogen and argon plasma-in-bubbles are employed in a concentrated nitric acid solution, thus enhancing conventional nitric acid solvolysis with plasma chemistry. A systematic process framework is presented, revealing key operational stages, including composite pretreatment, composite solvolysis, carbon fiber recovery/characterization, NO_x recovery, nitric acid circulation, and byproduct management, demonstrating their role in the overall process efficiency and environmental impact. Moreover, the research examined different processing conditions, including plasma power, acid concentration, and reactor design, while comparing open-air systems to systems equipped with single-stage or two-stage wet scrubbers for NO_x recovery. Remarkably, recycled fibers from plasma-assisted solvolysis demonstrated preserved or even slightly enhanced mechanical properties compared to those of the virgin fibers. Recycled carbon fibers originating from the operation at 1200 W and 12 M HNO₃ demonstrated the best mechanical properties with 3138.92 MPa tensile strength and 307.02 GPa Young's modulus. However, the parametric analysis revealed that operating the plasma reactor at 1200 W and 14 M, equipped with a two-stage scrubber, achieved optimal environmental performance.