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  1. Abstract

    Herein, we report a strategy to construct highly efficient perfluorooctanoic acid (PFOA) adsorbents by installing synergistic electrostatic/hydrophobic sites onto porous organic polymers (POPs). The constructed model material of PAF-1-NDMB (NDMB = N,N-dimethyl-butylamine) demonstrates an exceptionally high PFOA uptake capacity over 2000 mg g−1, which is 14.8 times enhancement compared with its parent material of PAF-1. And it is 32.0 and 24.1 times higher than benchmark materials of DFB-CDP (β-cyclodextrin (β-CD)-based polymer network) and activated carbon under the same conditions. Furthermore, PAF-1-NDMB exhibits the highestk2value of 24,000 g mg−1h−1among all reported PFOA sorbents. And it can remove 99.99% PFOA from 1000 ppb to <70 ppt within 2 min, which is lower than the advisory level of Environmental Protection Agency of United States. This work thus not only provides a generic approach for constructing PFOA adsorbents, but also develops POPs as a platform for PFOA capture.

     
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  2. Abstract

    Various robust, crystalline, and porous organic frameworks based on in situ‐formed imine‐linked oligomers were investigated. These oligomers self‐assembled through collaborative intermolecular hydrogen bonding interactions via liquid–liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks. The sequential formation of robust covalent linkages and highly reversible hydrogen bonds enforced long‐range symmetry and facilitated the production of large single crystals, with structures that were unambiguously determined by single‐crystal X‐ray diffraction. The unique hierarchical arrangements increased the steric hindrance of the imine bond, which prevented attacks from water molecules, greatly improving the stability. The multiple binding sites in the frameworks enabled rapid sequestration of micropollutant in water.

     
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  3. Abstract

    Rhenium is one of the most valuable elements found in nature, and its capture and recycle are highly desirable for resource recovery. However, the effective and efficient collection of this material from industrial waste remains quite challenging. Herein, a tetraphenylmethane‐based cationic polymeric network (CPN‐tpm) nanotrap is designed, synthesized, and evaluated for ReO4recovery. 3D building units are used to construct imidazolium salt‐based polymers with positive charges, which yields a record maximum uptake capacity of 1133 mg g−1for ReO4collection as well as fast kinetics ReO4uptake. The sorption equilibrium is reached within 20 min and akdvalue of 8.5 × 105mL g−1is obtained. The sorption capacity of CPN‐tpm remains stable over a wide range of pH values and the removal efficiency exceeds 60% for pH levels below 2. Moreover, CPN‐tpm exhibits good recyclability for at least five cycles of the sorption–desorption process. This work provides a new route for constructing a kind of new high‐performance polymeric material for rhenium recovery and rhenium‐contained industrial wastewater treatment.

     
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  4. Abstract

    To offset the environmental impact of platinum‐group element (PGE) mining, recycling techniques are being explored. Porous organic polymers (POPs) have shown significant promise owing to their selectivity and ability to withstand harsh conditions. A series of pyridine‐based POP nanotraps, POP‐Py, POP‐pNH2‐Py, and POP‐oNH2‐Py, have been designed and systematically explored for the capture of palladium, one of the most utilized PGEs. All of the POP nanotraps demonstrated record uptakes and rapid capture, with the amino group shown to be vital in improving performance. Further testing on the POP nanotrap regeneration and selectivity found that POP‐oNH2‐Py outperformed POP‐pNH2‐Py. Single‐crystal X‐ray analysis indicated that POP‐oNH2‐Py provided a stronger complex compared to POP‐pNH2‐Py owing to the intramolecular hydrogen bonding between the amino group and coordinated chlorine molecules. These results demonstrate how slight modifications to adsorbents can maximize their performance.

     
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  5. Abstract

    Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The range of properties characterized in COFs has rapidly expanded to include those of interest for numerous applications ranging from energy to environment. Here, a background overview is provided, consisting of a brief introduction of porous materials and the design feature of COFs. Then, recent advancements of COFs as a designer platform for a plethora of applications are emphasized together with discussions about the strategies and principles involved. Finally, challenges remaining for this type material for real applications are outlined.

     
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  6. Abstract

    The potential consequences of nuclear events and the complexity of nuclear waste management motivate the development of selective solid‐phase sorbents to provide enhanced protection. Herein, it is shown that 2D covalent organic frameworks (COFs) with unique structures possess all the traits to be well suited as a platform for the deployment of highly efficient sorbents such that they exhibit remarkable performance, as demonstrated by uranium capture. The chelating groups laced on the open 1D channels exhibit exceptional accessibility, allowing significantly higher utilization efficiency. In addition, the 2D extended polygons packed closely in an eclipsed fashion bring chelating groups in adjacent layers parallel to each other, which may facilitate their cooperation, thereby leading to high affinity toward specific ions. As a result, the amidoxime‐functionalized COFs far outperform their corresponding amorphous analogs in terms of adsorption capacities, kinetics, and affinities. Specifically, COF‐TpAb‐AO is able to reduce various uranium contaminated water samples from 1 ppm to less than 0.1 ppb within several minutes, well below the drinking water limit (30 ppb), as well as mine uranium from spiked seawater with an exceptionally high uptake capacity of 127 mg g−1. These results delineate important synthetic advances toward the implementation of COFs in environmental remediation.

     
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  7. Poly(pyridinium salts) (PPSs) with positive charges on the backbones were designed and synthesized from the transformation of bispyrylium salts. Such materials exhibited good uptake capacity for rhenium capture from water, and excellent selectivity of ReO 4 − from competing anions. Furthermore, the advantages of facile synthesis and large-scale preparation make this material promising for practical use in industry. 
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  8. null (Ed.)