Zhuang Liu,Xinyang Cai,Sandra Dirè,Emanuela Callone,Xiaolin Zhang,Jinming Luo,Francesco Parrino,Dawei Wang
The rapid development of semiconductor and electronics industries have urged novel adsorbents for fluoride removal from wastewater. In this study, we developed a metal-organic framework filter by in-situ implanting MIL-96(Al) onto Al mesh, which demonstrated effective and stable fluoride removal over a wide range of pH (3−11). The solid state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) results revealed that the different structural changes to which Al3 sites are subjected upon pH modifications trigger fluoride adsorption through Lewis interactions at acidic pH values and through ligand exchange mechanism at neutral/alkaline pH values. Moreover, the filter demonstrated limited Al ions leakage and satisfactory adsorption selectivity towards fluoride among chloride, nitrate, and sulfate, at concentrations up to 50-times higher than fluoride. As a proof of concept for practical applications, the developed filters were sealed in tandem into a home-made filter holder and tested for fluoride removal from real industrial wastewater. When 12 filters were used, fluoride concentrations decreased from 5.8 mg/L to below 1.5 mg/L after 10 min of hydraulic retention time in the filter holder over 5 consecutive cycles. We hope this work may provide new insights for the design of novel absorbents for fluoride removal.
Beibei Zhang,Guiju Xu,Lei Li,Xiaoli Wang,Na Li,Ru-Song Zhao,Jinming Lin
Trihalomethanes (THMs) and halonitromethanes are the two most dominant categories of volatile disinfection by-products that pose considerable public health concerns. The pretreatment and determination methods of THMs in low concentrations, particularly trichloronitromethane (TCNM), have always been the focus of researchers. Metal-organic frameworks, which are effective adsorbents, have considerable potential for solid-phase microextraction (SPME) because of their tuned pore structure, large surface area, and high thermal and chemical stabilities. In this study, MIL-96 was successfully fabricated and developed as a coating fiber for SPME of THMs and TCNM in water samples. Several extraction parameters (i.e., extraction temperature, extraction time, stirring rate, pH, and ionic strength) and desorption parameters (i.e., temperature and time) were investigated and optimized in detail. Ionic strength, extraction temperature, and pH/desorption temperature were identified as key factors that affected the SPME efficiencies of THMs and TCNM. The developed method under optimal conditions obtained wide linearity (0.02–50 µg/L), low limits of detection (0.0030–0.0110 µg/L), and high enrichment factors (81–1181) for detecting THMs and TCNM. The spiked recoveries (1 and 10 µg/L) and relative standard deviations ranged from 81.0% to 109.9% and from 3.92% to 10.10%. Notably, the developed SPME method could overcome thermal degradation and showed excellent performance for TCNM. These results indicated the applicability of MIL-96 as coating fiber.
Minghua Wang,Dan Guo,Bochong Wang,Jianyong Xiang,Kun Zhai,Tianyu Xue,Fusheng Wen,Yingchun Cheng,Congpu Mu
In this work, MIL-96 (Ga) was successfully synthesized by a microwave-assisted method and pyrolyzed at 700 o C to obtain Ga 2 O 3 /C (G-700) composites. After carbonization, Ga 2 O 3 nanoparticles were uniformly embedded in a porous carbon skeleton. The surface of MIL-96(Ga)-derived Ga 2 O 3 /C was used as a template for directional pyrrole polymerization. G-700@PPy composite materials were obtained by in-situ polymerization of pyrrole on the surface of G-700. A hierarchical interfacial structure was created with regulated dielectric properties. The effect of pyrrole doping content on the electromagnetic waves (EMWs) absorption properties of G-700@PPy composite materials was studied. The experimental result showed that the minimum reflection loss ( RL min ) value of G-700@PPy-3 composite materials reached -79.0 dB under a thin thickness of 1.58 mm, and the maximum effective absorption bandwidth (EAB) of 5.66 GHz was obtained under 1.78 mm. The results indicate that highly conductive PPy could significantly improve the impedance matching conditions and electromagnetic attenuation capacity of G-700 composite materials, which provided an important idea for optimizing the microwave absorption properties of low permittivity composites.
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