The sorption of Cr(VI) from aqueous solutions with macroporous resins which contain quarternary amine
groups (Lewatit MP 64 and Lewatit MP 500) was studied at varying Cr(VI) concentration, adsorbent dose,
pH, contact time and temperature. Batch shaking sorption experiments were carried out to evaluate
the performance of Lewatit MP 64 and Lewatit MP 500 anion exchange resins in the removal of Cr(VI)
from aqueous solutions. The concentration of Cr(VI) in aqueous solution was determined by UV–visible
spectrophotometer. The ion exchange process, which is dependent on pH, showed maximum removal of
Cr(VI) in the pH range 3–7 for an initial Cr(VI) concentration of 1×10−3 M. The optimum pH for Cr(VI)
adsorption was found as 5.0 for Lewatit MP 64 and 6.0 for Lewatit MP 500. The maximum Cr(VI) adsorption
at pH 5.0 is 0.40 and 0.41 mmol/g resin for Lewatit MP 64 and Lewatit MP 500 anion exchangers,
respectively. The maximum chromium sorption occurred at approximately 60 min for Lewatit MP 64
and 75 min for Lewatit MP 500. The suitability of the Freundlich and Langmuir adsorption models was
also investigated for each chromium–sorbent system. The uptake of Cr(VI) by the anion exchange resins
was reversible and so it has good potential for the removal of Cr(VI) from aqueous solutions. Both ion
exchangers had high bonding constants but Lewatit MP 500 showed stronger binding. The rise in the temperature
caused a slight decrease in the value of the equilibrium constant (Kc) for the sorption of Cr(VI)
ion