Photoelectrocatalytic removal of antibiotic ciprofloxacin using a photoanode based on Z-scheme heterojunction

Abstract

The photoelectrochemical method based on FTO/Fe2O3/BiOI@BiOBr photoanode was applied for the degradation of the ciprofloxacin molecule. The developed method was carried out using a reactor containing ciprofloxacin (3.0 × 10–5 mol L–1), containing a working electrode: FTO/Fe2O3/BiOI@BiOBr, a platinized titanium counter electrode and an Ag/AgCl/KCl (3.0 mol L–1) reference electrode, working potential of 2.0 V with ultraviolet radiation (9.0 W). The electrode was characterized by electrochemical, morphological, structural and optical techniques. When applying the degradation method, after one hour, the antibiotic molecule was degraded more than 90.0 %, being mineralized close to 52.0 %, in which the degraded samples were characterized by UV–vis spectrometry, determination of total organic carbon and UHPLC-Q-ToF-MS. Like this, the oxidation process proved to be efficient yielded a kinetic constant k = 3.7 × 10–2 min−1 and a half-life of 18.7 min. The charge transfer mechanism in the photoanode semiconductor material occurred by a Z-scheme recombination process. Finally, the mass spectroscopy experiments demonstrated that the ciprofloxacin oxidation process led to the formation of fourteen by-products, in which the degradation path was proposed in three steps.