Catalyzed oxidative degradation of methylene blue by in situ generated cobalt (II)-bicarbonate complexes with hydrogen peroxide

▶ Efficient degradation of methylene blue was disclosed with Co2+-HCO3−/H2O2 system. ▶ The system produces hydroxyl radicals as the main reactive species. ▶ Different complex species in situ formed between Co2+ and HCO3− were observed at different HCO3− concentrations. ▶ The complex [Co(HCO3)]+ formed at intermediate HCO3− concentrations (5-10 mM) was suggested more active than the others.