Oxidation of printed circuit board wastes in supercritical water

A feasibility study for oxidation of printed circuit board wastes with NaOH in supercritical water has been investigated. Experimentally, Br species in the printed circuit board resin was abstracted by sodium cations and the destruction efficiency of the waste was enhanced in the supercritical water oxidation (SCWO) process. By X-ray diffraction (XRD) spectroscopy, Cu2O, CuO, and Cu(OH)2 were found in the SWCO solid residue of the printed circuit board wastes. The extended X-ray absorption fine structural (EXAFS) spectra indicated that the bond distance of Cu–O in the residue was 1.87 Å with a coordination number of 2.61. Since the Cu–Br species was not observed by XRD and EXAFS spectroscopies, one may eliminate the possibility that the copper was involved in the abstraction of bromine species from the resin matrix in the SCWO process.