The purpose of this study was modification of activated carbon (AC) to prepare a new selective sorbent for
removal of uranium ion. The modification was performed by introducing carboxyl groups onto AC using
ammonium persulfate (APS) in sulfuric acid solution followed by functionalization with 2-aminobenzoic acid
(ABA) as a selective ligand for U (VI) ion (UO22+) adsorption. The characterization of the synthetized sorbent
(AC-ABA) was carried out through several methods including potentiometry, scanning electron microscopy,
energy dispersive spectroscopy, x-ray diffraction and FT-IR to confirm successful functionalization of the sorbent
surface with oxygen and amine groups. The sorption of U (VI) on the unmodified AC and AC-ABA was investigated
as a function of contact time, sorbent content, initial uranium concentration, solution pH, and temperature
using batch sorption technique. In addition, the effect of various parameters on the U (VI) sorption capacity
was optimized by the response surface methodology as a potent experimental design method. The results indicated
that sorption of U (VI) under the optimal conditions was significantly improved onto AC-ABA compared to
AC. Kinetic studies displayed that the sorption process reached equilibrium after 100 min and followed the
pseudo-second-order rate equation. The isothermal data fitted better with the Langmuir model than the
Freundlich model. The maximum sorption capacity of AC-ABA for U(VI) was obtained to be 194.2 mg g 1 by the
Langmuir model under optimum conditions, which demonstrates the sorption capacity has been improved by the
modification process. The thermodynamic parameters (ΔH, ΔS and ΔG) indicated that sorption of uranium onto
AC-ABA was an endothermic and spontaneous process. The sorption studies on radioactive effluents of the nuclear
fuel plant represented high selectivity of AC-ABA for removal of uranium in the presence of other metal
ions, and the selectivity coefficients significantly improved after modification of the sorbent. Application of ACABA
for treatment of industrial effluents containing heavy and radioactive metal ions show high potential and
capability of the proposed method.
