Adsorption behavior of Pd(II) from aqueous solutions by D201 resin

Abstract

The adsorption and desorption behaviors of Pd(II) on D201 resin were investigated. The effects of parameters including HCl concentrations, initial metal ion concentrations, contact time, and temperature on the adsorption of Pd(II) were studied by batch method. The HCl concentration for studying the effects was set from 0.01 to 2 mol·L −1 and the optimal adsorption condition is in 0.01 mol·L −1 HCl solution. The adsorption isotherm of Pd(II) on D201 resin was determined and the equilibrium data fitted the Langmuir model better than the Freundlich model. The maximum uptake capacity of Pd(II) was 253 mg·g −1 at 298 K. The adsorption could be best described by the liquid film diffusion model. The enthalpy variation (ΔH) and entropy change (ΔS) of adsorption were equal to 2.49 kJ·mol −1 and 74.8 J·(mol·K) −1 respectively, indicating that the adsorption was endothermic in nature. Furthermore, the negative value of ΔG showed that movement of adsorbate from the solution to adsorbent surface was a spontaneous process. Pd(II) could be eluted with 0.5 mol·L −1 HNO 3 solution. Thomas model was applied to experimental column data to determine the characteristic parameters of the column useful for process design.