An enhanced adsorption and desorption procedure of Nd(III) onto D113-III resin were prepared with various chemical methods.Batch studies were carried out with various pH,contact time,temperature and initial concentrations,and then column studies were conducted.The results showed that the optimal adsorption condition was at pH value of 6.90.The process was fast initially and arrived equilibriumwithin 60 h.The resin exhibited a high Nd(III) uptake as 232.56 mg/g at 298 K.The adsorption data fitted well with pseudo-second-order kinetic model.Thermodynamic parameters were studied,which indicated that the adsorption process was spontaneous and endothermic.Thomas model was delineated here to predict the breakthrough curves based on the experimental column study data.In the elution test,1 mol/LHCl solution could achieve a satisfactory elution rate,which indicated that D113-III resin could be regenerated and reused.Finally,the IRspectroscopic technique was undertaken,and a novel adsorption mechanism was proposed.
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.
