Effect and mechanism of norfloxacin removal by Eucalyptus leaf extract enhanced theZVI/H₂O₂ process

Theconventional ZVI/H_₂O_₂ technology suffers from poor reagent utilization,excess iron sludge generation, and strong low pH dependence. Therefore,eucalyptus leaf extract (ELE) was introduced to improve ZVI/H_₂O_₂ technology, and the efficacy and mechanism of ELEpromoting ZVI/H_₂O_₂ technology were deeply explored. The results showedthat the norfloxacin (NOR) removal and k_obs of the ZVI/H_₂O_₂/ELE process were enhanced by 35.64 % and 3.27 times,respectively, compared to the ZVI/H_₂O_₂ process. In the ZVI/H_₂O_₂ process, the production of three reactive oxygenspecies (ROS: ^¹O_₂，·O_₂^⁻，·OH) was effectively promoted by ELE so that thereaction efficacy was significantly enhanced. Moreover, the attack anddegradation of pollutants by ROS was the main way to remove pollutants. Withthe introduction of ELE, the reactive sites on the catalyst appearance wereincreased to some extent, and the Fe(III)/Fe(II) cycle was improved. Theanalysis showed that ELE is rich in titratable acids and the ZVI/H_₂O_₂ technology is promoted mainly by lowering the pH of theprocess. In addition, the chelation of ELE and the reduction in pH by the ELEsynergistically enhanced the ZVI/H_₂O_₂ technology, which significantly improved the reagentutilization (4.70 times for ZVI and 3.03 times for H_₂O_₂), broadened the pH range of the technology (6–9) and wasable to effectively reduce the iron sludge contamination (30.33 %) of theprocess. Therefore, the study offers an important value to study eucalyptusleaves in micron-scale ZVI-Fenton technology. Copyright © 2024 Elsevier B.V. All rights reserved.