ION EXCHANGE KINETICS AND EQUILIBRIUM STUDIES OF METAL IONS ONTO A HYBRID CATION EXCHANGER: POLYANILINE?SN(IV)TUNGSTOPHOSPHATE

Polyaniline based hybrid cation exchange material Polyaniline?Sn(IV)tungstophosphate (PANI?TWP) has been synthesized by simple sol?gel method and applied for the sorption study of rare earth metal ions on the exchanger. The present investigation deals with the evaluation of feasibility of PANI?TWP toward sorptive removal of rare earth metal ions from aqueous solution. For this various parameters like influence of concentration of metal ions, contact time and temperatures on sorption of ions were investigated using batch method. The sorption process was found to be temperature dependent and increased with the increase in reaction temperature. A comparative kinetic modelling analysis of the sorption data favours the pseudo-second order model and equilibrium adsorption data were best fitted by Langmuir isotherm model for the present system. Apparent activation parameters like activation energy (Ea) and entropy of activation (?S*) along with self diffusion coefficient (Di) were also computed using Arrhenius equation. The negative values of ? ?S? ^* indicate an associative mechanism and there is no significant change in the internal structure of the sorbent during the sorption of counter ions.