Sulfite activation by cobaltosic oxide nanohydrangeas for tetracycline degradation: Performance, degradation pathways and mechanism

Sulfite has been used as a classic reductant for the dehalogenation and reduction of organic compounds for a long time, it is recently deemed as a promising alternative (for persulfate) to generate sulfate radical for wastewater treatment due to its low price and eco-toxicity. In contrast with the enormous work developed in the field of tetracycline (TC) degradation via PMS activization, sulfite activization could play a important role in TC degradation but there is only very few available reports in this area. Herein, the novel and efficient CoNHs nanocatalyst is designed and developed, via immobilization of hydrangea-shaped Co3O4 nanoparticles onto graphitic carbon nanosheet (GCN), for the degradation of tetracycline via sulfite activation. The detailed characterizations have confirmed that CoNHs possesses a nanohydrangea-shaped structure with high microporosity. The comparison with other supports (such as CeO2 and MoS2), CoNHs provides the highest degradation efficiency in TC degradation, due to the synergistic effect between Co3O4 and GCN. Free radical quenching experiments and EPR analysis confirm that SO4•- and O2•- are major reactive oxygen species in the CoNHs/sulfite system. This work could provide a simple, economical and durable cobalt-based catalyst for organic wastewater treatment via sulfite activation.