Co-Ion Effect on Cr³⁺ Sorption by Amberlyst-15(H⁺)

Cr3+ sorption on strong acid exchanger Amberlyst-15(H+) is studied as a function of time and temperature using CrCl3.6H(2)O and [Cr-4(SO4)(5)(OH)(2)] solutions. The rate is found to be governed by a mixed diffusion for both the solutions and faster for Cl1- solution than SO4 (2-). The exchange capacities are found to be higher for Cl1- system than SO4 (2-). From the rate constant values, the energies of activation are calculated using the well-known Arrhenius equation. Equilibrium data is explained with the help of the Langmuir equation. The Langmuir parameters are also found to be higher for exchange from the chloride solutions. Various thermodynamic parameters (Delta H-o, Delta S-o, and Delta G(o)) for Cr3+ exchange on the resin are calculated. The Delta G(o) values are found to be negative while Delta H-o and Delta S-o are positive for both the Cr3+/Cl1- and Cr3+/SO4 (2-) systems. It is suggested that in case of Cl1- solutions, the metal is exchanged as Cr3+, while in case of SO4 (2-) solutions, the metal exchanging specie is CrSO4 (+).