title: Postsynthetically Modified Covalent Organic Frameworks for Efficient and Effective Mercury Removal.
abstract: A key challenge in environmental remediation is the design of adsorbents bearing an abundance of accessible chelating sites with high affinity, to achieve both rapid uptake and high capacity for the contaminants. Herein, we demonstrate how two-dimensional covalent organic frameworks (COFs) with well-defined mesopore structures display the right combination of properties to serve as a scaffold for decorating coordination sites to create ideal adsorbents. The proof-of-concept design is illustrated by modifying sulfur derivatives on a newly designed vinyl-functionalized mesoporous COF (COF-V) via thiol-ene "click" reaction. Representatively, the material (COF-S-SH) synthesized by treating COF-V with 1,2-ethanedithiol exhibits high efficiency in removing mercury from aqueous solutions and the air, affording Hg2+and Hg0capacities of 1350 and 863 mg g-1, respectively, surpassing all those of thiol and thioether functionalized materials reported thus far. More significantly, COF-S-SH demonstrates an ultrahigh distribution coefficient value (Kd) of 2.3 × 109mL g-1, which allows it to rapidly reduce the Hg2+concentration from 5 ppm to less than 0.1 ppb, well below the acceptable limit in drinking water (2 ppb). We attribute the impressive performance to the synergistic effects arising from densely populated chelating groups with a strong binding ability within ordered mesopores that allow rapid diffusion of mercury species throughout the material. X-ray absorption fine structure (XAFS) spectroscopic studies revealed that each Hg is bound exclusively by two S via intramolecular cooperativity in COF-S-SH, further interpreting its excellent affinity. The results presented here thus reveal the exceptional potential of COFs for high-performance environmental remediation.
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Briana
authors.initials: B
authors.lastname: Aguila
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Jason
authors.identifier: 0000-0003-4894-3561
authors.initials: J
authors.lastname: Perman
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, Oak Ridge, Tennessee 37831, United States.
authors.forename: Lyndsey D
authors.identifier: 0000-0003-4359-0197
authors.initials: LD
authors.lastname: Earl
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, Oak Ridge, Tennessee 37831, United States.
authors.forename: Carter W
authors.identifier: 0000-0002-1809-9577
authors.initials: CW
authors.lastname: Abney
authors.affiliation: Zhejiang Key Laboratory of Additive Manufacturing Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , 1219 Zhongguan West Road, Ningbo, Zhejiang 315201, China.
authors.forename: Yuchuan
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University , Shanghai 200240, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wei
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Wojtas
authors.affiliation: Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
authors.forename: Shengqian
authors.identifier: 0000-0002-1897-7069
authors.initials: S
authors.lastname: Ma