Unraveling the Origin of Enhanced Activity of the Nb₂O₅/H₂O₂ System in the Elimination of Ciprofloxacin: Insights into the Role of Reactive Oxygen Species in Interface Processes

Abstract

The overlooked role of reactive oxygen species (ROS), formed and stabilized on the surface of Nb2O5 after H2O2 treatment, was investigated in the adsorption and degradation of ciprofloxacin (CIP), a model antibiotic. The contribution of ROS to the elimination of CIP was assessed by using different niobia-based materials in which ROS were formed in situ or ex situ. The formation of ROS was confirmed by electron paramagnetic resonance (EPR) and Raman spectroscopy. The modification of the niobia surface charge by ROS was monitored with zeta potential measurements. The kinetics of CIP removal was followed by UV–vis spectroscopy, while identification of CIP degradation products and evaluation of their cytotoxicity were obtained with liquid chromatography–mass spectrometry (LC-MS) and microbiological studies, respectively. Superoxo and peroxo species were found to significantly improve the efficiency of CIP adsorption on Nb2O5 by modifying its surface charge. At the same time, it was found that improved removal of CIP in the dark and in the presence of H2O2 was mainly determined by the adsorption process. The enhanced adsorption was confirmed by infrared spectroscopy (IR), total organic carbon measurements (TOC), and elemental analysis. Efficient chemical degradation of adsorbed CIP was observed upon exposure of the Nb2O5/H2O2 system to UV light. Therefore, niobia is a promising inorganic adsorbent that exhibits enhanced sorption capacity toward CIP in the presence of H2O2 under dark conditions and can be easily regenerated in an environmentally benign way by irradiation with UV light.

Copper(II) phosphate as a promising catalyst for the degradation of ciprofloxacin via photo-assisted Fenton-like process

“…306, 285, 263, 147, confirming successful degradation of the antibiotic. After 6 h of the reaction, the most intense peak occurred at m/z = 263 and was assigned to the CIP molecule in which the piperazine moiety is degraded (see Table 2 ) 41 . It is important to stress that the intensity of the most intense m/z peak, after such a long reaction time, was ca.…”

FeV3O8 Nanorods for Photodegrading Multiple Dyes

“…The flat-band potential ( E fb ) of 0.61 eV could be obtained from the plot of C 2– versus potentials. Therefore, the top of the VB (the highest occupied molecular orbital, HOMO) was determined to be 0.81 eV, and the bottom of the CB (the lowest vacant molecular orbital, LUMO) was calculated to be −1.57 eV. − Meanwhile, a photoelectrochemical-transient photocurrent response test of the prepared FeV 3 O 8 nanorods is displayed in Figure d. The i – t plots were recorded with the light on and off every 100 s up to 800 s, for which it can be seen that the anodic potential enhanced sharply under laser irradiation and disappeared quickly when the light source was switched off, which are attributed to the fast charge-carrier transfer and separation rate of the 1D structure FeV 3 O 8 catalyst under light excitation. , …”

Effects of experimental bleaching gels containing co-doped titanium dioxide and niobium pentoxide combined with violet light

“…However, Prado et al [15] showed that generating hydroxyl and superoxide radicals. Since the greatest e ciency of this reaction is observed under acidic conditions (pH ∼3) [41], the potential of the Nb 2 O 5 incorporated into the 6% HP gel with an average pH of 6.0-6.5 may not have been fully observed.…”