Hydroxylamine-assisted catalytic degradation of ciprofloxacin in ferrate/persulfate system

In this study, ferrate (Fe(VI)) was used as catalyst to activate persulfate (PS) for the removal of ciprofloxacin (CIP) from aqueous solution. Hydroxylamine (HA) was used to accelerate the reduction and regeneration of Fe(II) from the Fe(VI) + PS system. It was found that 91.5% of 30 μM CIP was decomposed within 60 min in the PS + Fe(VI)/HA system, which is 25.9% higher than that in the PS + Fe(VI) system. In the PS + Fe(VI)/HA system, the removal of CIP increased with the decrement of initial solution pH, whereas inorganic anions (i.e. HCO 3 − , Cl − , NO 3 − ions) and humic acid had slightly inhibitory effects on CIP removal. The radical scavenging experiments and the electron paramagnetic resonance (ESR) tests confirmed that the addition of HA in the PS + Fe(VI) system can accelerate the generation of reactive oxygen species (ROS) such as sulfate radicals (SO 4 − ) and hydroxyl radicals ( OH), which played important roles for the removal of CIP in the PS + Fe(VI)/HA system. CIP degradation intermediates were also identified and the pathways were proposed. This study suggested a new approach for catalytic degradation of CIP by ferrate.