物理化学学报 >> 2021, Vol. 37 >> Issue (8): 2010042.doi: 10.3866/PKU.WHXB202010042

所属专题： 二维光催化材料

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二维层状NiO/g-C3N4复合材料在无铁光电类芬顿体系中有效去除环丙沙星的研究

贾晓庆1, 白晓宇1, 吉喆喆2, 李轶1,*(), 孙妍2, 秘雪岳2, 展思辉2,*()   

  1. 1 天津大学理学院，天津 300072
    2 南开大学环境科学与工程学院，天津 300071
  • 收稿日期:2020-10-19 录用日期:2020-11-18 发布日期:2020-11-23
  • 通讯作者: 李轶,展思辉 E-mail:liyi@tju.edu.cn;sihuizhan@nankai.edu.cn
  • 基金资助:
    国家自然科学基金(21722702);国家自然科学基金(21874099);天津市自然科学基金(17JCJQJC45000);天津市科委重点技术研发项目(18YFZCSF00730);天津市科委重点技术研发项目(18YFZCSF00770);天津市科委重点技术研发项目(18ZXSZSF00230);天津市科委重点技术研发项目(19YFZCSF00740);天津市科委重点技术研发项目(20YFZCSN01070)

Insight into the Effective Removal of Ciprofloxacin Using a Two-Dimensional Layered NiO/g-C3N4 Composite in Fe-Free Photo-Electro-Fenton System

Xiaoqing Jia1, Xiaoyu Bai1, Zhezhe Ji2, Yi Li1,*(), Yan Sun2, Xueyue Mi2, Sihui Zhan2,*()   

  1. 1 School of Science, Tianjin University, Tianjin 300072, China
    2 College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
  • Received:2020-10-19 Accepted:2020-11-18 Published:2020-11-23
  • Contact: Yi Li,Sihui Zhan E-mail:liyi@tju.edu.cn;sihuizhan@nankai.edu.cn
  • About author:Email: sihuizhan@nankai.edu.cn (S.Z.)
    Email: liyi@tju.edu.cn; Tel.: +86-22-27403475 (Y.L.)
  • Supported by:
    the Natural Science Foundation of China(21722702);the Natural Science Foundation of China(21874099);the Natural Science Foundation of Tianjin City of China(17JCJQJC45000);the Tianjin Commission of Science and Technology as Key Technologies R&D Projects(18YFZCSF00730);the Tianjin Commission of Science and Technology as Key Technologies R&D Projects(18YFZCSF00770);the Tianjin Commission of Science and Technology as Key Technologies R&D Projects(18ZXSZSF00230);the Tianjin Commission of Science and Technology as Key Technologies R&D Projects(19YFZCSF00740);the Tianjin Commission of Science and Technology as Key Technologies R&D Projects(20YFZCSN01070)

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摘要：

环丙沙星(CIP)的过量使用已经对生态环境造成了很大的威胁。本文设计了一种新型无铁的光电类芬顿体系用于降解水中的CIP。采用溶剂热法合成了NiO/g-C3N4复合材料。通过XRD分析，确定了不同催化剂的晶相和化学组成; 红外光谱进一步证实了NiO/g-C3N4复合材料的分子结构，结果表明，成功地合成了NiO/g-C3N4复合材料。利用SEM观察了材料的形貌，结果表明性能最佳的NiO/g-C3N4-60%为二维花状结构。TEM进一步证明NiO/g-C3N4-60%具有片层状结构。由于层状结构，NiO/g-C3N4-60%具有较大的比表面积和丰富的活性位点，有利于电子的传输。XPS分析表明Ni2+和Ni3+共存于NiO/g-C3N4-60%复合材料中并且NiO/g-C3N4-60%具有低配位氧缺陷。EPR谱也证实了氧空位的存在，氧空位不仅促进了H2O2的活化，而且有利于金属离子形成稳定的混合价态。UV-Vis-DRS、PL和电化学测试表明NiO/g-C3N4-60%具有最强的光吸收能力、最低的电荷转移电阻和最快的电荷分离效率，有利于活性物质的生成和CIP的快速降解。因此，花状NiO/g-C3N4-60%在光电类芬顿体系中表现出光电协同作用，不仅可以通过Ni3+/Ni2+之间的转化将电芬顿过程中产生的H2O2有效分解为·OH，同时也能够产生光生电子和空穴，促进光照下·OH、·O2-和h+的生成，从而提高环丙沙星的降解效率。以催化性能最佳的NiO/g-C3N4-60%为催化剂时，在90 min内CIP的降解率达到将近100%，120 min时矿化效率达到82.0%，与传统芬顿体系(最佳pH值为2.8–3.5)相比，新型光电类芬顿体系具有较宽的pH范围，当pH值为6时，降解率仍可达78.8%。NiO/g-C3N4-60%在光电类芬顿体系中也表现出良好的结构稳定性，连续5次循环后，降解效率仍保持在96.3%。根据HPLC-MS的结果，提出了CIP降解的两种可能途径。本研究为废水中抗生素的快速降解提供了理论依据。

关键词: 二维层状, NiO/g-C3N4, 光电类芬顿体系, 环丙沙星, 花状复合材料

Abstract:

Excessive use of ciprofloxacin (CIP) has proven to be a significant threat to the ecological environment. In this work, a novel Fe-free photo-electro-Fenton system was designed for the degradation of CIP in water. The NiO/g-C3N4 composites were synthesized by a simple solvothermal method. The crystalline phases and chemical compositions of the different catalysts were determined via X-ray diffraction (XRD) analysis. Fourier transform infrared (FT-IR) spectroscopy further confirmed the molecular structures of the different composites. The results proved the successful synthesis of NiO/g-C3N4 composites. The morphology of the material was obtained using scanning electron microscopy (SEM), which showed that the structure of the optimal NiO/g-C3N4-60% was two-dimensional and flower-like. The transmission electron microscopy (TEM) analysis further proved that the NiO/g-C3N4-60% possessed a layered structure. Owing to the layered structure, the NiO/g-C3N4-60% boasts of a large specific surface area and abundant active sites, which were beneficial for the transmission of electrons and oxidation of CIP. Furthermore, it was evident from the X-ray photoelectron spectroscopy (XPS) analysis that the Ni2+ and Ni3+ coexisted, and there was low coordination oxygen with defects in the NiO/g-C3N4-60% composite. The electron paramagnetic resonance (EPR) spectrum also proved the existence of oxygen vacancies, which not only facilitated the activation of H2O2, but also promoted the formation of stable mixed valence states of metal ions. UV-vis diffuse reflection spectrum (UV-Vis DRS), photoluminescence (PL), and electrochemical tests showed that NiO/g-C3N4-60% exhibited the strongest light absorption capacity, lowest charge transfer resistance, and fastest charge separation efficiency, which was beneficial for the generation of active species and the rapid degradation of CIP. Therefore, the flower-like NiO/g-C3N4-60% composites exhibited photoelectric synergy in the photo-electro-Fenton process. They not only effectively decomposed the H2O2 produced in the electro-Fenton process into ·OH by the conversion of Ni3+/Ni2+, but also generated photogenerated electrons and holes to promote the production of ·OH, ·O2–, and h+ under light irradiation to improve the degradation efficiency of CIP. When the optimal NiO/g-C3N4-60% served as a catalyst in the photo-electro-Fenton system, the degradation efficiency of CIP reached approximately 100% in 90 min and the mineralization efficiency reached 82.0% in 120 min. In addition, compared with the traditional Fenton system (the optimal pH value of which is 2.8–3.5), the novel photo-electro-Fenton system possessed a wider range of pH, with a final CIP degradation efficiency of 78.8% at a pH value of 6. The NiO/g-C3N4-60% also demonstrated excellent structural stability in the photo-electro-Fenton system. After five consecutive cycles, the degradation efficiency was maintained at 96.3%. Based on the results of high-performance liquid chromatography-mass spectrometry (HPLC-MS), two possible pathways for CIP degradation were proposed. This study provides a theoretical basis for the rapid degradation of antibiotics in wastewater.

Key words: Two-dimensional layered, NiO/g-C3N4, Photo-electro-Fenton system, Ciprofloxacin, Flower-like composite