Enhancing hydrogen peroxide activation of Cu Co layered double hydroxide by compositing with biochar: Performance and mechanism

In this study, CuCo layered double hydroxide/biochar composite (CuCo LDH/BC) was prepared and employed for activating H2O2 to degrade ciprofloxacin (CIP), a common fluroquinolone antibiotic detected in water environment. The as-synthesized catalysts were also comprehensively characterized to study the physiochemical properties. For the catalytic activity, the degradation rate of CuCo LDH/BC to CIP was approximately 1.5 times higher than that of CuCo LDH. The improved catalytic activity can be ascribed to the synergistic effect between CuCo LDH and BC, such as more functional groups, accelerated electron transfer, and varied charge distribution. Meanwhile, CuCo LDH/BC/H2O2 could degrade CIP efficiently in a wider pH range comparing with CuCo LDH/H2O2, and the efficiency was approximately 84.7% at neutral pH within 90 min. The generation of OH, O2- and 1O2 in CuCo LDH/BC/H2O2 system were then verified by electron spin resonance (ESR) technology. The quenching experiments indicated that both non-radical pathway (1O2) and radical pathway (OH, O2-) led to CIP degradation, in which O2- and 1O2 made major contribution. Then, the intermediate products of CIP during catalytic reaction were monitored by high-performance liquid chromatography-mass spectrometry (HPLC-MS), and the environmental risk of these degradation intermediates was tested through seed germination experiments. This study tends to provide valuable information for LDH/BC application in heterogeneous Fenton-like reaction.