Iodine Adsorption in Metal Organic Frameworks in the Presence of Humidity

Used
nuclear fuel reprocessing represents a unique challenge when dealing
with radionuclides such as isotopes of 85Kr and 129I2 due to their volatility and long half-life. Efficient
capture of 129I2 (t1/2 = 15.7 × 106 years) from the nuclear waste stream
can help reduce the risk of releasing I2 radionuclide into
the environment and/or potential incorporation into the human thyroid.
Metal organic frameworks have the reported potential to be I2 adsorbents but the effect of water vapor, generally present in the
reprocessing off-gas stream, is rarely taken into account. Moisture-stable
porous metal organic frameworks that can selectively adsorb I2 in the presence of water vapor are thus of great interest.
Herein, we report on the I2 adsorption capacity of two
microporous metal organic frameworks at both dry and humid conditions.
Single-crystal X-ray diffraction and Raman spectroscopy reveal distinct
sorption sites of molecular I2 within the pores in proximity
to the phenyl- and phenol-based linkers stabilized by the I···π
and I···O interactions, which allow selective uptake
of iodine.