Catalytic ozonation performance of graphene quantum dot doped MnOOH nanorod for effective treatment of ciprofloxacin and bromate formation control in water

A catalyst [email protected] was successfully synthesized by attaching graphene quantum dots (GQDs) on the surface of MnOOH nanorods to boost catalytic ozonation of antibiotic, exemplified by ciprofloxacin (CIP). The result demonstrated that the [email protected]/O3 system had the greatest CIP removal effectiveness, followed by that of MnOOH/O3 and O3 only. The 0.02 mM CIP was degraded with 99.9% efficiency in 30 min in the presence 9.6 mg L-1 of O3 catalyzed by 12.5 mg L-1 of [email protected] The kinetic rate constants ​​were in the order: [email protected]/O3 (0.161 min−1) > MnOOH/O3 (0.079 min−1) > O3 (0.055 min−1). The [email protected] could enhance CIP degradation and inhibit BrO3- formation in different water sources. Results of scavenger and electron paramagnetic resonance (EPR) experiments demonstrated that oxygen radical (O2•-), singlet oxygen (1O2), and hydroxyl radicals (•OH) were involved in CIP degradation by the [email protected]/O3 system. Accordingly, the degradation pathways of CIP and mechanism of catalytic ozonation over [email protected] were investigated and proposed. This research is expected to shed light on the connection between carbonaceous material and metal hydroxide in catalytic ozonation.