Effective periodate activation of direct Z-scheme g-C3N4/Cu2O heterojunction for photocatalytic norfloxacin degradation, anti-bacterial activity and toxicity assessment

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2025-01, Vol.504, p.159143, Article 159143
• Main Authors: Gu, Qinyi, Rong, Jian, Zhang, Yuzhe, Zheng, Xudong, Zhou, Ziyao, Li, Zhongyu, Xu, Song
• Format: Article
• Language: English
• Subjects: Crystal plane structure; Direct Z-scheme heterojunction; g-C3N4/Cu2O composite; Norfloxacin degradation; Photocatalytic activity
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.159143

[Display omitted] •A direct Z-scheme g-C3N4/Cu2O heterojunction was successfully constructed.•g-C3N4/Cu2O heterojunction showed good photocatalytic and antibacterial activity.•Z-scheme heterojunction and periodate activation promoted formation of free radicals.•Mechanism of photocatalytic norfloxacin degradation for g-C3N4/Cu2O was proposed. Advanced oxidation technology based on photocatalytic activation of periodate (PI) is considered an effective method for treating contaminants in water. This paper studied the properties and mechanism of norfloxacin (NOR) degradation by Cu2O and its composites. The reticulated graphitic carbon nitride (RCN) prepared by supramolecular self-assembly showed a wide visible light response range, improving photogenerated carriers’ production efficiency. Besides, RCN/Cu2O with direct Z-scheme heterojunction was constructed by in-situ growth of Cu2O, and the unique crystal structure of Cu2O was considered the key to the efficient adsorption and activation of PI. The results showed that the degradation efficiency of RCN/Cu2O on NOR reached 98% within 10 min by activating PI under visible light irradiation. The separation and transfer of electrons were mainly accelerated because of the direct Z-scheme heterojunction. Meanwhile, S. aureus was used to evaluate the toxicity of the degraded solution and to study the anti-bacterial properties of photocatalysts. The energy band structure and degradation mechanism of RCN/Cu2O were deduced based on electron spin resonance (ESR) and density functional theory (DFT). Besides, the degradation path of NOR was obtained by analyzing the intermediates. NOR was mainly attacked by ·O2–, ·OH, and 1O2, resulting in piperazine ring transformation, decarboxylation, defluorination and quinolone group transformation, so NOR was transformed into small molecule substances. This work provides a feasible technology for preparing environmentally friendly materials for the rapid degradation of antibiotic wastewater by photocatalytic activation of PI.