A comparison of various XAD-Amberlite resins impregnated with dicyclohexyl-18-crown-6 for strontium removal

In the present study, four different varieties of Amberlite resin impregnated with dicyclohexyl-18-crown-6 were employed as an adsorbent for the selective extraction of strontium ions (Sr2+) from nitric acid solutions and dicyclohexyl-18-crown-6 impregnated in XAD-4 resin shows highest adsorption of Sr2+ from nitric acid solution. The effect of important parameters such as concentration of nitric acidic in the medium, adsorbent dosage, contact time, initial Sr (II) concentration and temperature were investigated in a batch system. The results demonstrated that the adsorption rate is high in the first 30 min and equilibrium was achieved after 300 min at 3 mol/L nitric acid medium. The results of the kinetic evaluations fit excellently with the pseudo-second-order model with a correlation coefficient R2 = 0.998. The prepared adsorbent extracts Sr (II) by following the Langmuir isotherm with a maximum adsorption capacity of 9.17 mg/g. Thermodynamic investigations indicated that the Sr (II) adsorption is an exothermic and spontaneous process. Strontium ions desorbed from resin in an acceptable percentage (98.9%) with double distilled water. In addition, the adsorption capability of the adsorbent in real water samples and also the effect of the existence of coexisting ions on the extraction of Sr (II) were assessed.