Postsynthetic ligand exchange for the synthesis of benzotriazole-containing zeolitic imidazolate framework.

The introduction of a triazole-based ligand to the zeolitic imidazolate framework-7 via a postsynthetic ligand exchange strategy not only maintains its framework, high stability and morphology, but also provides extra uncoordinated nitrogen atoms to improve the π-π and Lewis acid-base interactions.

Zeolitic imidazolate framework-8 for fast adsorption and removal of benzotriazoles from aqueous solution.

1H-benzotriazole (BTri) and 5-tolyltriazole (5-TTri) are emerging pollutants; the development of novel materials for their efficient adsorption and removal is thus of great significance in environmental sciences. Here, we report the application of zeolitic imidazolate framework-8 (ZIF-8) as a novel adsorbent for fast removal of BTri and 5-TTri in aqueous solution in view of adsorption isotherms, kinetics and thermodynamics, desorption, and adsorbent regeneration. The adsorption of BTri and 5-TTri on ZIF-8 was very fast, and most of BTri and 5-TTri were adsorbed in the first 2 min. The adsorption for BTri and 5-TTri follows a pseudo-second-order kinetics and fits the Langmuir adsorption model with the adsorption capacity of 298.5 and 396.8 mg g(-1) for BTri and 5-TTri at 30 °C, respectively. The adsorption was a spontaneous and endothermic process controlled by positive entropy change. No remarkable effects of pH, ionic strength, and dissolved organic matter on the adsorption of BTri and 5-TTri on ZIF-8 were observed. The used ZIF-8 could be regenerated effectively and recycled at least three times without significant loss of adsorption capacity. In addition, ZIF-8 provided much larger adsorption capacity and faster adsorption kinetics than activated carbon and ZIF-7. The hydrophobic and π-π interaction between the aromatic rings of the BTri and 5-TTri and the aromatic imizole rings of the ZIF-8, and the coordination of the nitrogen atoms in BTri and 5-TTri molecules to the Zn(2+) ions in the ZIF-8 framework was responsible for the efficient adsorption. The fast adsorption kinetics, large adsorption capacity, excellent reusability as well as the pH, ionic strength, and dissolved organic matter insensitive adsorption create potential for ZIF-8 to be effective at removing benzotriazoles from aqueous solution.

Fabrication of isoreticular metal-organic framework coated capillary columns for high-resolution gas chromatographic separation of persistent organic pollutants.

The unusual properties of metal-organic frameworks (MOFs), such as permanent nanoscale porosity, high surface area, uniformly structured cavities, and the availability of in-pore functionality and outer-surface modification, are advantageous for diverse applications. However, most existing methods for the synthesis of nanosized MOFs require an activation procedure or auxiliary stabilizing agents. Here we report a 1-min, room-temperature approach for the synthesis of nanosized isoreticular MOFs (IRMOFs) to fabricate IRMOF coated capillary columns for the high-resolution gas chromatographic separation of persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), polybrominated diphenylethers (PBDEs), and hexachlorocyclohexanes (HCHs). The developed method allows the synthesis of well-shaped nanosized IRMOFs within 1 min at room temperature without the need for any activation procedure or auxiliary stabilizing agents. The IRMOF coated capillary columns offer good separation efficiency that is generally comparable to that of a commercial HP-5MS column for POPs. The IRMOF-1 and IRMOF-3 coated capillary columns gave the theoretical plate values of 2293 and 2063 plates m(-1) for naphthalene, respectively, which are slightly smaller than those with a HP-5MS column (2845 plates m(-1)). The IRMOF-1 coated capillary column offered good resolution for the separation of several intractable PAH isomer pairs, such as anthracene/phenanthrene, benzo[a]anthracene/chrysene, and benzo[b]fluoranthene/benzo[k]fluoranthene, with resolutions of 3.0, 1.1, and 4.1, respectively, which were difficult to be baseline separated on a HP-5MS column with a resolution of 1.0. In addition, the IRMOF-1 and IRMOF-3 coated capillary columns offered a clear group separation of the PCB isomers and a linear range covering three orders of magnitude. The relative standard deviations for the five replicate separations of PAHs were 0.23-0.26% and 2.1-4.5% for retention time and peak area, respectively. The fabricated IRMOF coated capillary columns have been shown to be very promising for the separation of POPs with good reproducibility, high resolution, great selectivity, and a wide linear range.

Metal-organic frameworks for efficient enrichment of peptides with simultaneous exclusion of proteins from complex biological samples.

Metal-organic frameworks MIL-53, MIL-100 and MIL-101 demonstrate efficient enrichment of peptides with simultaneous exclusion of proteins from complex biological samples.

[Microwave assisted UV electrodeless discharge lamp photochemical degradation of 4-chlorophenol in aquatic solutions].

A microwave assisted UV electrodeless discharge lamp system (MW/UV) was used for photo-degradation of 4CP simulated wastewater. In order to evaluate the degradation efficiency of 4CP, UV spectrophotometry and ion chromatography were used for determination of 4CP and Cl- respectively. The degradation rate in MW/UV system was higher than that in the UV system within 120min, which were 52.40% and 21.56% respectively. The degradation efficiency was improved by increasing pH value of the solution, aerating O2 gas, enhancing light intensity, or adding H2O2 oxidant. The degradation of 4CP under MW/UV accords with the first order kinetics equation.