Floating BiOBr/Ti3C2 aerogel spheres for efficient degradation of quinolone antibiotics: Rapid oxygen transfer via triphase interface and effective charges separation by internal electric field.

Abstract

The limited transport of oxygen at the solid-liquid interface and the poor charge separation efficiency of single catalyst significantly impedes the generation of reactive oxygen species (ROS), thereby weakening the application potential of photocatalytic technology in water pollution control. Herein, a hollow porous photocatalytic aerogel sphere (calcium alginate/cellulose nanofibers (CA/CNF)) loaded BiOBr/Ti₃C₂, combining a favourable mass transfer structure with effective catalytic centers was firstly presented. The floatability and hollow pore structure facilitated rapid O₂ transfer via a triphase interface, thereby promoting the generation of ROS. The oxygen diffusion flux of aerogel spheres' upper surface in triphase system exhibited a 0.151 μmol·(m²·S)^-1 increase compared to that of the diphase one based on Finite element simulation (FEM). Furthermore, owing to the regulation of charge spatial distribution by Schottky junction of BiOBr/Ti₃C₂, internal electric field (IEF) of CA/CNF@BiOBr/Ti₃C₂ achieved 1.8-fold improvement compared with CA/CNF@BiOBr, thus enhancing the separation of photogenerated charges. Accordingly, the degradation efficiency and catalytic rate constant of moxifloxacin (MOX) by CA/CNF@BiOBr/Ti₃C₂ in triphase system have improved by 20.1% and 1.5 times compared to those of diphase system, respectively. Moreover, the potential to mineralize multiple quinolone antibiotics (FQs), high resistance to complex water disturbances and excellent stability were revealed in CA/CNF@BiOBr/Ti₃C₂. Besides, the triphase system based on CA/CNF@BiOBr/Ti₃C₂ confirmed the potential for large-scale water treatment application in 500 mL MOX circular flow, reaching 90% MOX removal within 120 min. This research clarifies the oxygen mass transfer mechanism and pathways to the enhanced ROS production in a triphase system, and provides new insights into designing efficient floatable photocatalyst and adaptive reaction devices for new pollutants remediation.