Document Abstract
Norfloxacin (NOFX), a broadly used fluoroquinolone antibiotic, has been a subject
of great concern in the past few years due to its undesirable e ect on human beings and
aquatic ecosystems. In this study, novel Mn doped ZnS (Mn:ZnS) quantum dots (QDs) were
prepared through a facile chemical precipitation method and used as photocatalysts for NOFX
degradation. Prior to photodegradation experiments, morphological and optical parameters of the
QDs were examined through transmission electron microscopy, scanning electron microscopy,
energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, ultraviolet-visible
spectroscopy, fluorescence spectroscopy, Brunauer–Emmett–Teller analysis, and di erential thermal
and thermogravimetric analyses. Mn:ZnS QDs exhibited excellent properties of photodegradation,
not only underUVirradiation but also in sunlight, which inducedNOFXto photodegrade. The utmost
photodegradation eciency was obtained under optimal conditions (25 mL of NOFX, 15 mg/L, pH 10,
60 min UV irradiation, 60 mgs QDs), adopting first order kinetics. In addition, hydroxyl radicals
produced by the conduction band electrons were found to be the primary reason dominating the
transformation of NOFX in basic conditions, while holes, oxygen atoms, as well as the doped metal
(Mn) enhanced the degradation. The QDs showed excellent reusability and stability in four repeated
cycles. Finally, four di erent pathways were predicted, derived from the identified intermediates,
with piperazinyl ring transformation being the primary one. It is expected that the synthesized
Mn:ZnS QDs could be utilized as ecient photocatalytic materials for energy conversion and
ecological remediation.