Enhanced catalytic degradation of ciprofloxacin over Ce-doped OMS-2 microspheres

A novel Ce-doped manganese oxide octahedral molecular sieve (Ce-OMS-2) was prepared by a reflux method and characterized by field emission scanning electron microscope, high resolution transmission electron microscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption isotherms, Xray diffraction and X-ray photoelectron spectroscopy. The Ce(0.48)-OMS-2 with Ce/Mn molar ratio of 0.48 was highly effective and stable for the degradation of ciprofloxacin in water. The characterized results indicated that Ce mainly entered the tunnel structure of OMS-2, significantly increasing the BET surface area from 72 m(2)/g for OMS-2 to 304 m(2)/g for Ce(0.48)-OMS-2. Moreover, the surface oxygen defects and surface labile oxygen significantly increased after the introduction of Ce into OMS-2, being determined by the O1s spectra and O-2-TPD analysis. The ESR and activity tests under different conditions suggested that the reduced manganese Mn(II) could interact with surface labile oxygen to form O-2(center dot-) and Mn(IV), resulting in the high activity of Ce(0.48)-OMS-2 to degrade the piperazine ring and the quinolone moiety of CIP into small molecular products. Simultaneously, the release of Mn(II) was inhibited by the electron transfer process on the micro-interface of Ce(0.48)-OMS-2. (C) 2015 Elsevier B.V. All rights reserved.