In this study, the 1,2,4,5-benzene tetracarboxylic acid
(H4btc) linker, 4,4′-bipyridine (4,4′-bipy)
auxiliary
ligand, and nickel nitrate salt were used to synthesize a Ni-loaded
metal–organic framework (AR-1) hydrothermally.
Various techniques were employed to characterize AR-1, including elemental analysis, single crystal X-ray diffraction
(SCXRD), Fourier transform infrared (FTIR) spectroscopy, and powder
X-ray diffraction (PXRD) investigations. According to single-crystal
X-ray data, the AR-1 exhibits a three-dimensional framework
constructed from propagating secondary building units (SBUs) containing
[Ni(btc)0.5(4,4′-bipy)H2O]·H2O. Furthermore, water molecules in the lattice provide extra
stability to the present MOF via hydrogen bonding interactions. Interestingly,
the AR-1 displays efficient, reversible iodine adsorption
in the vapor (maximum adsorption capacity 580 mg g–1) and solution phase. The high absorption of 127I is caused
by the physisorption and chemisorption attraction, creating a strong
interaction with the conjugated π-electron-rich aromatic system
from both ligands. Along with these interactions, free carbonyl oxygen
also exhibits chemical interaction. Specifically, Ni-MOF has excellent
water resistance and pH stability. Furthermore, dye adsorption studies
showed that AR-1 can adsorb cationic dyes (Methylene
blue) in an aqueous solution with a higher rate and selectivity than
the neutral dye (Martius yellow) but not anionic dyes (Cango red).
And, even after multiple cycles, the MOF retains its adsorption ability.
The outcome is that the AR-1 has improved 127I absorption and efficient cationic dye adsorption. This work sheds
light on the potential of three-dimensional (3D) Ni-MOF as dual-functional
adsorbents capable of addressing complex contamination scenarios involving
radioactive and organic pollutants. The insights gained from this
study provide a foundation for further optimization of MOF-based materials
to tackle the challenges associated with water pollution and hazardous
substance removal.
