Zirconium-Based Metal–Organic Framework for Removal of Perrhenate from Water

The
efficient removal of pertechnetate (TcO4–) anions from liquid waste or melter off-gas solution for an alternative
treatment is one of the promising options to manage 99Tc
in legacy nuclear waste. Safe immobilization of 99Tc is
of major importance because of its long half-life (t1/2 = 2.13 × 105 yrs) and environmental
mobility. Different types of inorganic and solid-state ion-exchange
materials have been shown to absorb TcO4– anions from water. However, both high capacity and selectivity have
yet to be achieved in a single material. Herein, we show that a protonated
version of an ultrastable zirconium-based metal–organic framework
can adsorb perrhenate (ReO4–) anions,
a nonradioactive surrogate for TcO4–,
from water even in the presence of other common anions. Synchrotron-based
powder X-ray diffraction and molecular simulations were used to identify
the position of the adsorbed ReO4– (surrogate
for TcO4–) molecule within the framework.