Waste printed circuit boards as novel potential engineered catalyst for catalytic degradation of orange II

Abstract

Waste printed circuit board (w-PCB) was used as novel catalyst for the degradation of an azo dye, orange II. Multi-techniques including thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectrum and scanning electron microscope were employed to characterize w-PCB. The experimental parameters, such as catalyst dosage, H2O2 dosage, solution pH, orange II concentration and temperature, were investigated for catalytic degradation of orange II. Orange II degradation is dependent on these parameters. Under conditions of w-PCB 2 g/L, H2O2 5 mL/L, pH 7.9, orange II 0.1 mmol/L and temperature 40 °C, the degradation reaches 97.98% within 6 h. The first-order kinetics manifests a good description of catalytic degradation of orange II. The calculated activation energy is 63 kJ/mol. The dominant •OH radical is identified by quenching tests in the w-PCB/H2O2 system. The time-dependent ultraviolet–visible spectra obviously reveal destruction of orange II. A plausible mechanism is proposed for orange II degradation in w-PCB/H2O2 system. This work provides a cleaner process of “waste treating waste”, and w-PCB can be potential engineered catalyst for the degradation of the azo dye.