Cationic Metal–Organic Framework-Based Mixed-Matrix Membranes for Fast Sensing and Removal of Cr2O72− Within Water

Abstract

Considering that metal–organic framework (MOF)-polymer mixed-matrix membranes (MMMs) can overcome the drawbacks of intrinsic fragility and poor processability of pure-MOF membranes, we designed MOF-based MMMs for efficient removal and fast fluorescence sensing of heavily toxic ions within water systems simultaneously. In this work, a series of MOF-based MMMs are prepared by mixing a hydrolytically stable cationic [Eu7 (mtb)5(H2O)16]·NO3 8DMA·18H2O (denoted as Eu-mtb) MOF material into poly (vinylidene fluoride) with high loadings up to 70%. The free volume at the interface between the polymer and Eu-mtb particles, combined with the permanent porosity and uniform distribution of Eu-mtb particles, enables these MMMs to show fast enrichment of Cr2O72- from solutions and consequently have a full contact between the analyte and MOFs. The developed Eu-mtb MMM (70wt% loading) thus shows both efficient removal and exceptional fluorescence sensing of Cr2O72- in aqueous media. The overall adsorption capacity of the Eu-mtb MMM (70 wt% loading) for Cr2O72- reaches up to 33.34 mg/g, which is 3.4 times that of powder-form Eu-mtb. The detection limit of the Eu-mtb MMM (70 wt% loading) for Cr2O72- is around 5.73 nM, which is lower than that of the reported powder-form Eu-mtb. This work demonstrates that it is feasible to develop flexible luminescent MOF-based MMMs as a significant platform for efficient removal and sensitive sensing of pollutants from water systems simultaneously.

Fluorescent water‐stable Zn (II) coordination polymers for selective aqueous detection of nitrophenols

“…The Zn‐2 based composite film was prepared according to the published literature with some modifications. [ 40,41 ] Briefly, 1.0 g poly (methyl methacrylate) (PMMA) was dissolved in ethylacetate (5 ml) and stirred for 12 h to form a sticky solution. A total of 10.0 mg grounded powders of Zn‐2 was added into the above solution and stirred for further 12 h to give a homogenous dispersion, and then, the dispersion was cast onto a glass plate using a scraper to produce a flat composite film under room temperature.…”

A new Cd(ii)-based coordination polymer as a luminescent sensor and adsorbent for dichromate ions

“…Further, the dichromate anion adsorption performance of CP 1 was found to be much better than most of the previously reported analogous materials, except for BUT MOF (Table 2). [40][41][42][43][44][45][46][47][48][49] This showcases the potential of CP 1 as an excellent adsorbent material for dichromate anions in aqueous solution.…”

Multi-functional metal–organic frameworks for detection and removal of water pollutions

“…116 Cui's group developed MOF-based mixed-matrix membranes (MMMs) for simultaneously removal and sensing of Cr 2 O 7 2− in aqueous system. 117 To be specific, a water stable cationic Eu-based MOF (Eu-mtb) was mixed with poly (vinylidene fluoride) to form MOF-based MMM. The obtained Eu-mtb MMM showed efficient removal ability towards Cr 2 O 7 2− with the adsorption capacity of 33.34 mg g −1 .…”