Abstract
AbstractMonolithic ZIF‐8 and ZIF‐67 adsorbents are synthesized at room temperature using a novel, ligand‐assisted method. Despite reductions in crystallinity within some of the samples, monolithic zeolitic imidazolate frameworks (ZIFs) have superior volume‐relative microporosity, total porosity, and surface areas relative to their particulate counterparts due to increased density. Samples synthesized using a single modulator, n‐butylamine, have a hierarchical porosity resulting in improved adsorption capacities in mid‐ to high‐ sorbate pressure regions. ZIF‐67 monoliths produced through mixed‐modulator synthesis, n‐butylamine and 1‐methylimidazole, are almost entirely microporous. Vapor adsorption isotherms find that, whilst their amorphous content results in increased water uptake, monolithic ZIFs are found to possess higher surface and adsorption hydrophobicity than traditional non‐polar adsorbents. Cosorption measurements with a common VOC toluene, under humid conditions, find that these monolithic ZIF samples outperform powder equivalents, with the mixed‐modulator ZIF‐67 monolith capturing 28% more VOC compared to the powder ZIFs studied due to its superior volumetric efficiency. This study provides insights into the benefits of modulator‐based tuning of porosity within monolithic ZIFs which, combined with their hydrophobicity, may facilitate their application for industrial organic vapor recovery or indoor air cleaning, where efficient hydrophobic adsorbents which can operate in humid environments are essential.
Highlights
(ZIFs) have superior volume-relative microporosity, total porosity, and surface areas relative to their particulate counterparts due to increased density
ZIFs are commonly utilized as adsorbents due to their high surface area and the ability to tune their pore size and properties based on the metal ion and imidazole linker species used,[1,3] with several dozen topologies and over a hundred unique structures for ZIFs existing.[1,4]
This study provides insights into the benefits of modulator-based tuning of porosity within monolithic ZIFs which, combined with their hydrophobicity, may facilitate their application for industrial organic formed by the reaction of 2-methylimidazole with zinc and cobalt salts, respectively, and both possess sodalite-like topology, with two apertures of sizes 3.4 and 11.6 Å.[5]
Summary
Cosorption measurements found that all porous ZIF powders and monoliths were capable of adsorbing high quantities of toluene, even at water partial pressures of 0.8 (i.e., 80% relative humidity), with performances all exceeding 75% of those under dry conditions. Monolithic sample ZIF-67 (ML) and was found to possess the highest volume-relative toluene capacity under dry conditions of 322 mg cm−3 significantly exceeding the capacities of powder ZIF-8 and ZIF-67, both of which had capacities in the range of 250–252 mg cm−3 This enhanced performance is present at the highest relative humidities, with ZIF-67 (ML) adsorbing 269 mg cm−3 of toluene following pre-exposure to a water partial pressure of 0.8. With comparable hydrophobicity to activated charcoal, as well as higher volume-relative VOC adsorption capacity under humid conditions, monolithic ZIF adsorbents could provide an effective alternative for air cleaning applications where water vapor is an important consideration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
