Improved degradation of anthraquinone dye by electrochemical activation of PDS

Electrochemical oxidation (EO) coupled with peroxydisulfate (PDS) activation as a synergistic wastewater treatment process (PDS/EO) was performed to degrade anthraquinone dye-Reactive Brilliant Blue (RBB) in aqueous solution. Introducing PDS into the EO improved the RBB removal than the sole PDS and conventional EO systems. The RBB could activate PDS to a certain degree by itself. By the comparison of various inorganic ions addition, it showed that adding NO₃^- as the background electrolyte was more effective than the systems using the Cl^- and SO₄^2-, respectively. In this PDS/EO-NO₃^- system, increasing PDS concentration (1-5 mmol L^-1) and current density (5-10 mA cm^-2) considerably promoted the degradation of RBB. The adjustment of the solution pH displayed that the acidic and neutral condition was beneficial to the RBB removal, and the synergistic effect was inverse ratio to the RBB initial concentration. Furthermore, the scavenger experiments verified that both SO₄^·- and HO· were the major active substances in the RBB decomposition, and other reactive oxygen species also had considerable contributions. Thereinto NO₃^- only act a catalytic agent to improve the generation of active matters in the PDS/EO-NO₃^-. Overall, the proposed synergistic process could serve as an efficient method for the degradation of anthraquinone dye.