Carbonate-enhanced catalytic activity and stability of Co3O4 nanowires for 1O2-driven bisphenol A degradation via peroxymonosulfate activation: Critical roles of electron and proton acceptors.

Transition-metal catalysts (TMCs) for peroxymonosulfate (PMS) activation suffer from low stability (i.e. severe metal leakage and poor reusability) when maintaining high activity in water decontamination. An innovative carbonate (CO32-)-mediated method to synchronously enhance the catalytic activity and stability of TMCs was developed herein. In a model PMS/Co3O4 nanowire system for bisphenol A (BPA) degradation, the first-order kinetic constant and total organic carbon removal ratio were increased by 202.27% and 71.32% upon adding CO32-, respectively. Meanwhile, the cobalt release amount was significantly reduced from 4.90 to 0.03 mg/L, and the number of reuse with high efficiency (>90% of BPA removal within 10 min) was augmented from 1 to 3 times. The CO32- buffered pH decline to repress metal leakage, and promoted Co(III) reduction into Co(II) to avoid the over-oxidation of catalyst. Under the driving of CO32-, the dominated reactive species were switched from •OH/SO4•- to 1O2 accompanying the migration of catalytic center from Co(II) to Co(III). The Co(III) and CO32-/OH- acted as electron and proton acceptors, respectively, to accelerate PMS decomposition into SO5•- and subsequent generation of vast 1O2. This work proposes a green way to construct novel 1O2-based catalytic systems with excellent activity and stability for pollution remediation.