Insight into the mechanism of Zr-Fe bimetallic CUGB-SOFs activating persulfate to degrade tetracycline in water

• Published in: Separation and purification technology 2025-06, Vol.359, p.130495, Article 130495
• Main Authors: Li, Wanting, Hu, Yang, Liu, Xuelin, Cheng, Xin, Dai, Yunrong, Yin, Lifeng, Hua, Qingsong
• Format: Article
• Language: English
• Subjects: Degradation mechanism; Persulfate activation; Supramolecular organic frameworks; Tetracycline; Zr-Fe bimetallic
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.130495

[Display omitted] •A hydrostable SOF (CUGB-SOF) was synthesized using Zr-core and H3TATAB-ligand.•Zr clusters partially substituted by Fe expand reaction zone for PMS activation.•CUGB-SOF-Fe/PMS removed 95 % tetracycline (TC) in 10 min and held for 9 cycles.•1O2 was identified as main active specie, while ·OH/SO4− played auxiliary roles.•Flexible chain charge transfer mechanism and TC degradation pathways are proposed. Tetracycline (TC), as a typical representative of antibiotic pollutants, persists in surface water and wastewater, and there is an urgent need to develop new treatment technologies to address this issue. Supramolecular organic frameworks (SOFs) can activate peroxymonosulfate (PMS) to oxidize TC, but they often suffer from poor activity and hydrostability. To address these issues, this study innovatively introduced 4,4′,4″-[(1,3,5-triazine-2,4,6-triyl) tris(azanediyl)] tribenzoic acid (H3TATAB) as a ligand to synthesize functionalized Zr based CUGB-SOFs. The morphology and structure of the CUGB-SOFs were characterized, revealing that adjacent H3TATAB molecules are interconnected through double hydrogen bonds, intertwine, and entangle with each other, ultimately forming an extremely complex two-dimensional wavy layered structure. Doped by multi-metal (Co, Cu, Fe), the CUGB-SOFs can effectively and consistently activate peroxymonosulfate (PMS) to generate abundant singlet oxygen (1O2) for the degradation of TC. Especially after cycles of experiments, CUGB-SOF-Fe still maintained TC degradation efficiency as high as 84.49 %, which breaks through the understanding of traditional hydrogen bond structure. It is believed that Zr dominates the aqueous stable, allowing CUGB-SOF-Fe to act as an electron shuttle, promoting PMS activation and thereby accelerating TC degradation. Finally, combined with the identification of key reactive oxygen species and the analysis of intermediate products by mass spectrometry, the degradation reaction mechanism of TC was proposed.