A type of polyaniline was synthesized and its Cr (VI) removal potential was investigated in this work. The
kinetics study, adsorption isotherm, pH effect, and thermodynamic study were examined in batch experiments.
Adsorption data for Cr (VI) uptake by polyaniline were analyzed according to Langmuir and Freundlich
adsorption models. Thermodynamic parameters for the adsorption system were determinated at 293 K, 303
K, and 313 K (∆H° ) 23.87 kJ mol-1
; ∆G° ) -10.76 to -13.13 kJ mol-1 and ∆S° ) 118.20 J K-1 mol-1
).
The positive values of both ∆H° and ∆S° suggest an endothermic reaction, increasing in randomness at the
solid-liquid interface during the adsorption process. ∆G° values obtained were negative, indicated that the
adsorption of the Cr (VI) ion on the surface of polyaniline was a spontaneous adsorption process. The kinetics
process can be described by a pseudosecond-order rate equation very well. The Cr (VI) adsorption capacity
tended to increase with a decrease of pH. The maximum uptake of Cr (VI) was 95.79 mg g-1
. These results
show that the polyaniline doped with sulfuric acid could be considered as a potential adsorbent for chromium
hexavalent ions in aqueous solutions.