A metal-organic framework modulated to site-isolate Cl˙ pendants via radical inter-conversion for degrading hard-to-ionize aqueous organic wastes

Minsung Kim, Md Al Mamunur Rashid, Yun Jeong Choe, Sang Hoon Kim, Jung Hyun Lee, Keunhong Jeong, Jongsik Kim

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1 Citation (Scopus)

Abstract

Compared with conventional ˙OH, Cl˙ is longer-lived, more selective to destabilizing refractory electron (e)-donating aqueous aromatics via radicalization, and renewable via e transfer from aromatics to enable Cl˙ ↔ Cl inter-conversion. To demonstrate the merits of Cl˙, a Cl pendant (ClSUP)-functionalized Zr-based metal-organic framework (UiO-66-Cl) was synthesized/modulated to impart mesoporosity for facilitating the diffusion of bulky aromatics into the porous architecture. UiO-66-Cl could site-isolate Cl anions (ClSUP) near Lewis acidic Zr4+ cations (LA) and Brønsted acidic -OH (BA), on which ˙OH was produced via homolytic H2O2 dissection, desorbed, and bound to ClSUP to yield Cl˙SUPvia exothermic radical inter-conversion of ˙OH → Cl˙SUP (referred to as the overall ˙OH → Cl˙SUP route). UiO-66-Cl provided greater LA/BA strengths than UiO-66 un-functionalized with ClSUP/ClSUP, thus requiring a lower energy for ˙OH desorption, which was identified as the rate-determining step of homolytic H2O2 dissection on UiO-66 or the overall ˙OH → Cl˙SUP route on UiO-66-Cl. Consequently, Cl˙SUP productivity on UiO-66-Cl was higher than ˙OH productivity on UiO-66 (activity↑). Moreover, UiO-66-Cl exploited Cl˙SUP as the major decomposer of e-donating aromatics (selectivity↑) via the e transfer pathway (recyclability↑), as proved by DFT calculations, EPR spectroscopy, and filtration/scavenging/isotope control runs. Furthermore, UiO-66-Cl was more resistant to structural deformation upon exposure to extreme reaction environments than UiO-66 (stability↑), as verified by DFT calculations/XRD analysis. Hence, UiO-66-Cl (Cl˙SUP) outperformed UiO-66 (˙OH), SO42−-functionalized iron oxide (SO4˙SUP), or NO3-modified Mn oxide (NO3˙SUP) in degrading e-donating, ionization-resistant aqueous aromatics (phenol, aniline, acetaminophen, sulfanilamide, and sulfamethoxazole) in terms of activity, selectivity, stability, and/or reusability.

Original languageEnglish
JournalJournal of Materials Chemistry A
DOIs
Publication statusAccepted/In press - 2023

Bibliographical note

Funding Information:
This work was supported by a grant from Kyung Hee University (KHU-20222209).

Publisher Copyright:
© 2023 The Royal Society of Chemistry.

ASJC Scopus subject areas

  • General Chemistry
  • Renewable Energy, Sustainability and the Environment
  • General Materials Science

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