Additive dependent synthesis of bismuth oxybromide composites for photocatalytic removal of the antibacterial agent ciprofloxacin and mechanism insight

Bismuth oxybromide composites were synthesized by solvothermal synthesis, applying triethanolamine (TEOA), sodium hydroxide (NaOH) and ammonium hydroxide (NH3 H2O) as the additives, which were denoted as S-TEOA, S-NaOH and S-NH3, respectively. The obtained samples were characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electron spin resonance spectrometry (ESR), Brunauer-Emmett-Teller (BET) measurement, and UV-Vis absorption spectrometry. The results showed that the samples consisted of the same phases containing BiOBr and Bi24O31Br10, and possess different structures, morphology and optical absorption properties depending on the additive. Their photoactivities were evaluated by degradation of ciprofloxacin (CIP) under visible light (lambda >= 420 nm) irradiation. The apparent rate constant value of the sample S-TEOA is 2.62 and 4.17 times higher than that of the samples S-NaOH and S-NH3. The possible formation mechanism of the sample S-TEOA and adsorption mode of CIP species on the prepared samples are discussed on the basis of the experimental results.