Copper-spent activated carbon as a heterogeneous peroxydisulfate catalyst for the degradation of Acid Orange 7 in an electrochemical reactor.

The exhausted activated carbon generated from the adsorption of heavy metal wastewater needs further treatment/disposal. In this study, a new application of copper-spent activated carbon (Cu-AC) was proposed. Cu-AC was used to activate peroxydisulfate (PDS) for the decolorization of Acid Orange 7 (AO7) and electrical current was introduced to enhance the process. The decolorization followed a pseudo-first-order kinetic pattern well (R(2) > 0.95). 92.4% of color removal at 60 min and 38.3% of total organic carbon removal at 180 min were achieved when initial pH value was 9.0, current density was 16 mA/cm(2), PDS concentration was 5 mM and Cu-AC dosage was 0.25 g/L. The radical scavengers including methanol, tert-butanol and phenol, as well as electron paramagnetic resonance test, were employed to investigate the oxidizing species responsible for AO7 decolorization. The stability of Cu-AC was confirmed by three recycle experiments.