Journal
POLYHEDRON
Volume 196, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.poly.2020.114980
Keywords
MIL-125(Ti); Chemical adsorption; Arsenic removal; Structure reforming
Categories
Funding
- National Natural Science Foundation of China [21276193, 201405008, 21601028, 21902022]
- Natural Science Foundation of Shandong Province [ZR2019QB026, ZR2018LB018]
- Dezhou University Scientific Research Foundation [2019xgrc07]
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The research investigated chemical adsorption behavior of arsenic on a microporous metal-organic framework (MIL-125(Ti)), achieving ultra-fast adsorption speed and excellent arsenic removal capability. Both As(III) and As(V) can easily replace ligands via competitive coordination and bind to the Ti active sites. The study provides a molecular-level understanding of the chemical adsorption mechanism of arsenic on MIL-125(Ti), solving the difficulty of removing low concentrations of arsenic.
The adsorption behavior of arsenic on adsorbent have been researched widely, but chemical adsorption of arsenic is uncommon. In this work, a kind of microporous metal-organic framework (MIL-125(Ti)) with columnar morphology and uniform size was solvothermally synthesized, and its chemical adsorption behavior and mechanism of arsenic were firstly investigated by experimental and simulation study. Remarkably, ultra-fast adsorption behavior and excellent arsenic removal capability was achieved. It takes only 20 min to rapidly remove 5 mg L-1 arsenic with 0.2 g L-1 MIL-125(Ti), which is far superior to the previously reported materials. Both experimental and simulation study results show that the adsorption of arsenic obeys a new chemical adsorption mechanism. Both As(III) and As(V) can easily replace the terephthalic acid ligand via competitive coordination and bind to the Ti active site of MIL-125(Ti). In addition, the reaction energy barriers for ligand substitution by H2O, As(III) and As(V) are 0.46, 0.33 and 0.15 eV, respectively, which further confirming that structure reforming of MIL-125(Ti) plays a key role for chemical adsorption. The study solves the difficulty of removing low concentration of arsenic and provides molecular-level understanding of the chemical adsorption mechanism of arsenic on MIL-125(Ti). (C) 2020 Elsevier Ltd. All rights reserved.
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