Oxidation of chloroquine drug by ferrate: Kinetics, reaction mechanism and antibacterial activity

• CLQ as an antiviral drug might be persistent pollutant in surface water. • CLQ oxidation by Fe(VI) fitted second-order kinetics. • The degradation of CLQ by Fe(VI) was highly dependent on pH. • Aromatic ring dealkylation and chloride ion substitution are the main pathway. • CLQ oxidation by Fe(VI) slightly increased antimicrobial effect towards E. coli . Chloroquine (CLQ) is required to manufacture on a larger scale to combat COVID-19. The wastewater containing CLQ will be discharged into the natural water, which was resistant to environmental degradation. Herein, the degradation of CLQ by ferrate (Fe(VI)) was investigated, and the biodegradability of the oxidation products was examined to evaluate the potential application in natural water treatment. The reaction between CLQ and Fe(VI) was pH-dependent and followed second-order kinetics. The species-specific rate constant of protonated Fe(VI) species (HFeO 4 − ) was higher than that of the FeO 4 2− species. Moreover, increasing the reaction temperature could increase the degradation rate of CLQ. Besides, HCO 3 − had positive effect on CLQ removal, while HA had negative effect on CLQ removal. But the experiments shows Fe(VI) could be used as an efficient technique to degrade co-existing CLQ in natural waters. During the oxidation, Fe(VI) attack could lead to aromatic ring dealkylation and chloride ion substitution to form seven intermediate products by liquid chromatography-time-of-flight-mass spectrometry (LC-TOF-MS) determination. Finally, a pure culture test showed that the oxidation of CLQ by Fe(VI) could slightly increase the antimicrobial effect towards Escherichia coli (E.coli) and reduce the toxicity risk of intermediates. These findings might provide helpful information for the environmental elimination of CLQ.