Core–shell adsorbents by electrospun MOF‐polymer composites with improved adsorption properties: Theory and experiments

Abstract

A new class of core-shell adsorbents has been created by electrospun metal-organic framework (MOF) particles embedded in polymer nanofibers, which have provided many unique properties compared to the existing MOF coating technologies. For the first time, we demonstrate the improved adsorption selectivity of CO 2 over N 2 using electrospun polymer/ZIF-8 adsorbents in experiments. Furthermore, an analytical model based on the assumption that the diffusivity in core is 10 times higher than that in shell is developed to describe the theory of improved selectivity for core-shell adsorbents that is validated against a more accurate finite element model developed in COMSOL. Our model shows three regimes including exclusive shell uptake, linear core uptake, and asymptotic core uptake. These regimes are related to material properties and uptake times, which could be used as design criteria to balance core stability, maximum selectivity, and maximum uptake. An advanced HAADF STEM tomography (Movie S1) shows that the shell thickness in the case of polymer/ZIF-8 is on the order of 10 nm, allowing the regime of maximum selectivity to be realized. Kinetically limited adsorption tests at 45 C demonstrate that these composite fibers can perform in a regime of selectivity and uptake for the separation of CO 2 and N 2 that is unobtainable by either the MOF or fiber independently, showing a great potential for postcombustion CO 2 capture.

In situ cyclodextrin metal–organic framework/electrospun composite fibers with biosafety for the removal of volatile organic compounds

“…[35][36][37] Unfortunately, high-loading MOF can lead to particle clustering and poor fiber formation, resulting in increased viscosity, needle clogging and so on. In contrast to the coupling of pre-synthesized MOF crystals with fibers, [38][39][40] in situ MOF growth on fibers would be an effective way to retain much more MOFs onto the surface of the fibers in a facile way, [41][42][43] and the resulting composite material is suitable for various applications. In this study, in order to induce b-CD-MOF formation, b-cyclodextrin (b-CD), which was used as the active site, was doped in PCL electrospun fibers.…”

Facile synthesis of Fe3O4@TMU‐12 (Co‐based magnetic MOF) for extraction of diazinon and chlorpyrifos from the environmental water samples

“…The adsorption process, in comparison with other methods, is a better procedure in terms of cost, simplicity, availability, effectiveness, and lack of sensitivity to toxic substances 22–25 . In MSPE, sorbents are typically magnetic nanoparticles (MNPs) coated with sorbents such as silica, activated carbon, polymers, and zeolites 26–28 . Since these sorbents have a small surface area to volume ratio, so the process needs long extraction times.…”

“…[22][23][24][25] In MSPE, sorbents are typically magnetic nanoparticles (MNPs) coated with sorbents such as silica, activated carbon, polymers, and zeolites. [26][27][28] Since these sorbents have a small surface area to volume ratio, so the process needs long extraction times. Metal-organic frameworks (MOFs) are organic-inorganic hybrid materials that have attracted much attention as advanced materials due to exclusive features such as huge surface area, high and adjustable porosity, regular structure, well chemical stability, and unique adsorption capability.…”