Two series of mixed matrix membranes (MMMs) have been synthesized via in situ UV polymerization for the removal of N2 from CH4. MIL-100(Cr) particles activated at different temperatures were used as fillers. MIL-100(Cr) activated at 150°C with CH4-selective adsorption was incorporated with poly(ethylene oxide)-based polymer to improve the CH4/N2 separation performance, and that activated at 250°C with N2-selective adsorption and diffusion was incorporated with fluoropolymer to improve the N2/CH4 separation performance. The effects of the filler loadings on the gas permeation and separation performances were investigated. The optimum MMMs with 5 wt.% loading of MIL-100(Cr) activated at 150°C exhibited a 70% increased CH4/N2 permselectivity of 5.0 with a 37% increased CH4 permeability of 11.2 Barrer (tested at 0.2 MPa and 35°C). The optimum MMMs with 5 wt.% loading of MIL-100(Cr) activated at 250°C exhibited a 106% increased N2 permeability of 71.5 Barrer with an 89% increased N2/CH4 permselectivity of 1.9.
We developed a feasible strategy to obtain the defective MIL-100(Cr) (De-M) via doping 3,5-pyridinedicarboxylate and subsequently loaded polydivinylbenzene (PDVB) by thermal deposition to obtain a hydrophobic MOFs composite (De-M@PDVB). De-M 10 (10 % defective ligand/total ligands) exhibited excellent performance for the capture of toluene due to uniform particle size, high specific surface area and pore volume. Subsequent thermal deposition with PDVB further increased the hydrophobicity, as-obtained De-M 10 @PDVB in the dynamic adsorption experiment showed about 2 and 1.5 time adsorption capacity as that of primary MIL-100(Cr) and De-M 10 under 50 % RH at 298 K. In addition, the toluene uptake of De-M 10 @PDVB (0.95, 298 K) in static adsorption experiments was 1320 mg/g, much higher than many reported MOFs. Furthermore, De-M 10 @PDVB could be regenerated at 378 K, demonstrating its excellent regenerability at low temperature. The adsorption mechanism of toluene on De-M 10 @PDVB could be attribute to the π-π stacking interaction between the benzene ring of toluene with H 3 BTC and adsorption sites offered by the incorporation of H 2 DL in the framework of MIL-100(Cr) according to XPS analysis. Our finding provided a novel strategy by constructing defective MIL-100(Cr) and introducing PDVB to enhance efficient adsorption for toluene capture even in humid air.
A metal-organic frameworks (MOFs), cauliflower-like MIL-100(Cr), has been facilely prepared through simple reflux method for the first time and characterized by XRD, FT-IR, SEM and XPS. The MOFs was found to be useful for the simultaneous and selective electrochemical detection of microgram Cd(II), Pb(II), Cu(II), and Hg(II) in aqueous solution. The detection was performed by the square wave anodic stripping voltammetry (SWASV). The MIL-100(Cr) modified electrode showed an excellent selectivity and stability for Cd 2+ , Pb 2+ , Cu 2+ , Hg 2+ determinations. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as pH, deposition potential and deposition time were optimized for the purpose of determination of traces of metal ions .
Isostructural metal–organic frameworks (MOFs) MIL-100(Fe) and MIL-100(Cr), which have identical organic linker and Mobil Thirty-Nine zeolitic type, but different metal ions , were exploited as stationary phases for capillary gas chromatographic separation of alkane isomers. MIL-100(Fe) coated capillary column showed great capability and high efficiency for the gas chromatographic separation of alkane isomers without the need of temperature-programming, while MIL-100(Cr) coated capillary column gave poor performance for the separation. The separation performance of MIL-100(Fe) coated capillary column was even better than commercial HP-5MS and GS-GasPro capillary columns. The determined McReynolds constants, adsorption enthalpies and entropies showed that MIL-100(Fe) coated capillary column gave relatively weaker interaction with alkane isomers than MIL-100(Cr) coated capillary column. The relative standard deviations of repeatability for C7 alkane isomers on MIL-100(Fe) coated capillary column were 0.06–0.16%, 1.1–1.5%, 2.8–3.0% and 2.1–2.4% for retention time, half peak width, peak height and peak area, respectively.
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