A Novel Sonochemical Approach for Enhanced Recovery of Carbon Fiber from CFRP Waste Using Mild Acid-Peroxide Mixture

A novel sonochemical method is proposed for the recovery of carbon fiber from carbon fiber reinforced polymer (CFRP) composites by treatment with a mixture of dilute nitric acid and hydrogen peroxide in the presence of ultrasound. A maximum resin decomposition ratio of 95% could be obtained for the epoxy matrix. SEM and TGA data showed that the recovered fibers had very little or no epoxy resin and their tensile strength was comparable to that of the virgin fiber. ATR-FTIR, MALDI-TOF/MS, and 1H NMR analysis of the recovered solid and liquid byproducts showed the formation of decomposition products of cross-linked epoxy resin through nitration and oxidation reactions. This process opens the possibilities of an environmentally more benign process for CFRP waste decomposition and recovery of carbon fiber in the presence of ultrasound and H2O2 by eliminating the need for strong chemicals and high reaction temperatures and pressures.