Severe harmful effects of per-fluoroalkyl and polyfluoroalkyl substances (PFAS) to ecology and human health have led many countries to continuously upgrade their control for PFAS, which poses higher requirements for the efficient removal of PFAS in water to ensure water resource security. In the present study, the three-dimensional/two-dimensional (3D/2D) structure of metal oxide immobilized on a carbon substrate of the Fe-based metal–organic frameworks (Fe-MOF) heat treatment derivative H:MIL-101(Fe) was constructed. H:MIL-101(Fe) could completely remove PFOA from pure water within 5 min, and complete recovery was achieved within 30 s. H:MIL-101(Fe) exhibited stable properties and can maintain its initial adsorption percentage after four cycles of PFAS adsorption. It was found that the high hydrophobic interface of H:MIL-101(Fe) was formed by partial carbonization during the Fe-MOF heat treatment, and a large number of unsaturated ═C–H bonds on the unstructured benzene ring were generated. Furthermore, cationic chelating agent, such as cetyltrimethylammonium bromide, were mixed with PFAS to synthesize more hydrophobic long-chain complexes; six PFAS containing 4–8 carbon atoms could be completely coadsorbed in surface water within 10 min at pH 7.0, mainly depending on the mechanism of hydrophobic interaction. This study develops a novel adsorption material that can match PFAS types to realize the effective coadsorption of PFAS in water, which provides new insights for removal of PFAS with different carbon chains based on improving hydrophobic interactions between adsorbents and adsorbates.
Fe-MOF derivative (M-300) is successfully prepared by thermal treatment using MIL-100(Fe) as a precursor. The resulting M-300 catalyst displays excellent performance in the degradation of volatile organic compounds (VOCs) and the bacteriostasis to Escherichia coli under the visible light. In addition, the catalyst also exhibits the capacity of acetaldehyde degradation under actual sunlight. The high activity is attributed to the abundant exposure of the unsaturated Fe 2+ active site, which can significantly promote the transfer of photogenerated electron and the oxygen reduction process, thus improving the efficiency of the entire photocatalytic oxidation reaction. This work shows the application prospect of MOFs derivatives in the field of indoor photocatalytic purification, and also provides a new insight into the study of catalyst modification in photocatalytic degradation of pollutants.
Minghui Xiang,Zhen Lu,Siyang Li,Hui Li,Chen Wang,Jin Zhang,Lide Jin,Chunyang Li
In recent years, new heterogeneous catalysts derived from metal organic frameworks (MOFs) have been widely used in advanced oxidation processes (AOPs). In this work, zeolite imidazole framework-67 (ZIF-67) and sulfide nanozero-valent iron (S-Fe) were used as precursors to prepare S-Fe/Co bimetallic nanoparticles embedded in graphitized carbon (S-Fe/Co@GC) and used to activate peroxymonosulfate (PMS) to degrade tetrabromobisphenol A (TBBPA). Morphological and structural characterization indicated that S-Fe/Co@GC compared to pre-carbonization, the pore size of the material became larger, formed a graphite carbon skeleton with excellent electrical conductivity. In a 0.2 g/L S-Fe/Co@GC and 0.6 mM PMS system, 96.1% of TBBPA (20 mg/L) was degraded within 30 min, and the degradation yielded a total organic carbon (TOC) removal of 56.2% in 60 min. This excellent catalytic activity was attributed to the synergistic effect of graphitic carbon, sulfide nanozero-valent iron and metallic cobalt. Radical quenching experiments and electron paramagnetic resonance (EPR) technology indicated that reactive oxygen species (ROS) included HO • , SO 4 •− , O 2 •− and 1 O 2 , among which O 2 •− plays a leading role in the degradation of TBBPA. Based on the LC-MS analysis of the degradation intermediates, the degradation pathway of TBBPA in the S-Fe/Co@GC/PMS system was proposed. In addition, S-Fe/Co@GC showed a low ion leaching rate, and the regenerated S-Fe/Co@GC still had high catalytic performance. This work will extend the development of MOFs encapsulate functional nanoparticle materials for environmental remediation.
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