Extraction of palladium (II) from nitric acid medium by imidazolium nitrate immobilized resin

Imidazolium nitrate functional groups (Im–NO3) were anchored onto a polystyrene–divinylbenzene resin matrix, and investigated for the extraction of palladium (II) from nitric acid medium. The rate of extraction and distribution coefficient, Kd, mL/g, of palladium (II) were measured as a function of extent of functionalization, and concentrations of nitric acid, sodium nitrate and palladium nitrate. Kd values of palladium (II) show a maximum in 3.0 M–4.0 M nitric acid. Slope analysis of the distribution data obtained at various aqueous phase nitrate concentrations and resin phase exchanging capacity suggest the involvement of anion exchange mechanism for the extraction of palladium (II) from nitric acid medium. The ion exchange isotherm was fitted using Langmuir adsorption model and the apparent ion exchange capacity (b = 88 mg/g) was determined. The performance of the resin under dynamic conditions was evaluated by following a breakthrough curve and the data was fitted using Thomas model.