Abstract
Seawater uranium extraction is a promising sustainable energy pathway; however, practical application requires advanced adsorbents that combine reversible, high uranium‐uptake capacity with the ability to track sorption cycles. Herein, we report self‐indicating porous organic polymers (POPs),
Sal‐POP
and
Im‐POP
, containing uranyl (UO
2
2+
) ion‐coordinating salphen and
o
‐hydroxy imine cores with UO
2
2+
binding energies up to −71.94 kcal mol
−1
as uranium adsorbents, and demonstrate their reversible, high uranium extraction capacities up to 0.114 g g
−1
h
−1
. Enabled by the extended conjugation of salphen unit and strong UO
2
2+
binding,
Sal
‐
POP
readily changes color at uranium saturation from yellow to black and allows visual tracking of uranium adsorption/desorption cycles. With a high density of UO
2
2+
binding sites, both
Sal
‐
POP
and
Im
‐
POP
demonstrate rapid, reversible, and high uranium uptake capacity, with distribution coefficients (
K
d
) of 1.88 × 10
5
and 2.94 × 10
5
mL g
−1
, and removal efficiencies up to 70% and 78%
.
The uranyl capture is highly reversible, and the POP color changes from black to yellow upon simple elution with Na
2
CO
3
, thus acting as a self‐indicating POP adsorbent.