A novel adsorbent was prepared by NH4HCO3-modifying nanoalumina dioxide and was employed for the separation/preconcentration
of ReVII ions from aqueous solution. It was found that
ReVII ions could be adsorbed quantitatively (above 94%)
on modified nano-Al2O3 in the pH range of 2.0–3.0,
while only 8.3% of ReVII ions were adsorbed on unmodified
nano-Al2O3. Effects of the pH, concentration
of elution solution, and interfering ions on the recovery of ReVII were systematically investigated. Adsorption kinetics for
ReVII was found to be very fast, and equilibrium was reached
within 5 min following the pseudo-second-order model with observed
rate constants (k
2) of 14.44 g·mg–1·min–1 at 298 K. The overall
rate process appeared to be influenced by both external mass transfer
and intraparticle diffusion. The sorption data could be well interpreted
by the Langmuir model with a maximum adsorption capacity of 1.94 mg·g–1 of ReVII on modified nano-Al2O3. Moreover, the thermodynamic parameters showed the
spontaneous and endothermic nature of the adsorption process. Finally,
modified nano-Al2O3 as the sorbent was successfully
applied to the separation of ReVII from the ore samples
with satisfactory results.