Efficient degradation of antibiotics over Co(II)-doped Bi2MoO6 nanohybrid via the synergy of peroxymonosulfate activation and photocatalytic reaction under visible irradiation

Developing efficient photocatalysts based on the peroxymonosulfate (PMS) activation for effective degradation of threatening antibiotic contamination under visible light is still a challenging subject. Herein, a Co-doped Bi2MoO6 (CBMO) spherical crystals were synthesized via a facile hydrothermal method and used to degrade artificial antibiotic wastewater via PMS activation under visible light. The obtained 3 wt% Co-doped B2MoO6 (3CBMO) can effectively remove 98.95% of norfloxacin (NOF) within 40 min, 100% of tetracycline (TC) and metronidazole (MNZ) within 30 min. Compared with the contrasting catalysts, the superior catalytic activity of 3CBMO was attributed to the synergistic effect of photocatalytic and Co(II) activated PMS degradations. Quenching tests in combination with EPR measurements revealed that the hole (h+), sulfate (SO4-•) and hydroxyl (•OH) were the primary radicals all contributed to NOF degradation. The influences of initial concentration, catalyst dosage, PMS dosage and various interfering ions (NO3-, Cl-, SO42-, and HCO3-) on the degradation efficiency of NOF were systematically examined. Furthermore, possible degradation pathways of NOF were proposed by LC-MS. This novel 3CBMO catalyst might be a promising candidate for degradation of the main sources of antibiotic contamination in pharmaceutical wastewater.