Lujian Liu,Xia Ruan,Hong Liu,Jun Dong,Xianyuan Fan,Xiaoyong Ning,Yanxin Wang
In this study, nano zero-valent iron (nZVI) was synthesized and used as an activator for monopersulfate (PMS) to remove norfloxacin (NOR) in water. The degradation rate of NOR reached 99 % under the optimum conditions in the pH range of 3.0–9.0. The Fe 0 in nZVI was consumed in the reaction and gradually transformed into γ-FeOOH. Furthermore, the SO 4 − · and OH − · were proved to be the main free radicals involved in NOR degradation by nZVI-PMS, and SO 4 − · was the dominant free radical. A possible degradation pathway for NOR was examined via time-of-flight mass spectrometry analysis. NOR was degraded through defluorination, decarboxylation and cleavage of the piperazine ring. The intermediates were oxidized and decomposed into CO 2 , H 2 O, F − and other small organic products. Some NOR and its degradation products were adsorbed by nZVI and γ-FeOOH. This investigation could provide useful guidance for future research on NOR degradation via PMS-based advanced oxidation processes.
Qi Chen,Ling Hu,Yingzhang Shi,Cheng Liu,Yidong Hou,Jinhong Bi,Jimmy C. Yu,Ling Wu
Heterogeneous photocatalytic degradation of antibiotic involves the activation of antibiotic molecules and the photocatalytic oxidation process. However, the simultaneous improvement of these processes is still a challenge. Herein, S-scheme heterojunctions consisted of Cu 2 O nanocluster with defective WO 3 nanosheets were constructed for efficient photocatalytic degradation of levofloxacin (LVX). The typical CNS-5 composite (5 wt% Cu 2 O/WO 3 ) achieves an optimal LVX degradation efficiency of 97.9% within 80 min. The spatial charge separation and enhancement of redox capacity were realized by the formation of S-scheme heterojunction between Cu 2 O and WO 3 . Moreover, their interfacial interaction would lead to the loss of lattice oxygen and the generation of W 5+ sites. It is witnessed that the C–N of piperazine ring and C O of carboxylic acid in LVX are coordinated with W 5+ sites to build the electronic bridge to activate LVX, greatly promoting the further degradation. This work highlights the important role of selective coordination activation cooperated with S-type heterojunctions for the photocatalytic degradation and offers a new view to understand the degradation of antibiotics at molecular level.
Yanbin Wang,Zezhou Shi,Haibo Shen,Qiushuang Xing,Yunqing Pi
Efficient and selective removal of organic contaminants using traditional radical-dominated Advanced Oxidation Processes (AOPs) in complex environmental matrices is challenging, especially under high salinity conditions. This study proposes an alternative approach using iron (II) phthalocyanine-supported g-C 3 N 4 composite (FePc/CN) as a peroxymonosulfate (PMS) activator to efficiently remove organic contaminants. The FePc/CN-PMS process was selective towards the elimination of various organic contaminants, and those compounds with lower ionization potential value can be effectively degraded after reaction for 10 min. Results from radical quenching experiments, electron spin resonance (ESR), and PMSO chemical probe indicated that the dominant active species in the FePc/CN-PMS process are high-valent iron-oxo species (Fe IV O 2+ ), rather than the long-recognized SO 4 •− and •OH radical. A total of 22 intermediate products resulting from the degradation of levofloxacin (LVF) were identified by LC-MS. Additionally, two degradation pathways of LVF were proposed, with the piperazine ring of LVF being the primary site of degradation. The 5%FePc/CN-PMS system demonstrates resistance to ubiquitous inorganic anions and dissolved organic matter (DOM) in an aquatic environment, enabling efficient removal of (LVF) even under high salinity conditions. Furthermore, the 5%FePc/CN catalyst exhibits good chemical stability and reusability, making it a viable option for practical water remediation.
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