1 research outputs found
Imidazole-2yl-Phosphonic Acid Derivative Grafted onto Mesoporous Silica Surface as a Novel Highly Effective Sorbent for Uranium(VI) Ion Extraction
A new
imidazol-2yl-phosphonic acid/mesoporous silica sorbent (ImPÂ(O)Â(OH)<sub>2</sub>/SiO<sub>2</sub>) was developed and applied for uraniumÂ(VI)
ion removal from aqueous solutions. The synthesized material was characterized
by fast kinetics and an extra-high adsorption capacity with respect
to uranium. The highest adsorption efficiency of UÂ(VI) ions was obtained
for the reaction system at pH 4 and exceeded 618 mg/g. The uraniumÂ(VI)
sorption proceeds quickly in the first step within 60 min of the adsorbent
sites and ion interactions. Moreover, the equilibrium time was determined
to be 120 min. The equilibrium and kinetic characteristics of the
uraniumÂ(VI) ions uptake by synthesized sorbent was found to follow
the Langmuir–Freundlich isotherm model and pseudo-second-order
kinetics rather than the Langmuir, Dubinin–Radushkevich, and
Temkin models and pseudo-first-order or intraparticle diffusion sorption
kinetics. The adsorption mechanism for uranium on the sorbent was
clarified basing on the X-ray photoelectron spectroscopy (XPS) analysis.
The model of UO<sub>2</sub><sup>2+</sup> binding to surface of the
sorbent was proposed according to the results of XPS, i.e., a 1:1
U-to-P ratio in the sorbed complex was established. The regeneration
study confirms the ImPÂ(O)Â(OH)<sub>2</sub>/SiO<sub>2</sub> sorbent
can be reused. A total of 45% of uranium ions was determined as originating
from the sorbent leaching in the acidic solutions, whereas when the
basic solutions were used, the removal efficiency was 12%