The adsorption characteristics for In3+ ions and a standard binary mix of In3+/Fe3+ ions on polyacrylamido-2- methylpropane sulfonic acid-g-natural rubber (PAMPS-g-NR) and its vulcanized form were investigated. The adsorption capacity for In3+ was investigated by the batch immersion method. The following parameters were investigated in this study: pH, initial metal concentration, temperature, and regeneration. The adsorption data were fitted with the Freundlich isotherm. Thermodynamic parameters, including Gibbs free energy, enthalpy, and entropy indicate that In3+ adsorption onto grafted NR is a feasible, spontaneous, and exothermic process in the temperature range 303-313 K. Separation of metal ions from a binary solution based on ionic radius using vulcanized grafted NR was also investigated. The influences of method of vulcanization, solution temperature and electron dose were studied on adsorption separation efficiency for metal ion mixtures. It was found that the vulcanized rubber can act as a selective adsorbent.
