The Fundamental Study Of Palladium Adsorbing On D113 Ion Exchange Resin

Palladium is a kind of rare and precious metal element of platinum group. There is still some palladium in the electroless plating waste solution produced during the preparation processes of palladium and palladium alloy composite membranes. If this part of palladium can be recovered and reused effectively, the preparing cost of palladium and palladium alloy composite membranes will be reduced markedly. It is will be beneficial for developing and applying the palladium and palladium alloy composite membranes in industrial scales. In this study, the related fundamental issues of recovering the palladium from the waste solution using the ion exchange resin technique were carried out to provide basic information for further studies.Through the resin selection experiments, the D113 resin showed a better capability among the four kind resins of D418, D113, 152 and AB-8. In the static adsorption experiment, based on 400ml waste solution, effects of resin amount, time, temperature and pH on adsorption behavior were investigated. The results indicated that the adsorption efficiency of Pd increased with the amount of resin used, and reached to 60% when the 4g resin was used; the adsorption amount of Pd increased with a increase of the adsorption time, the equilibrium time was about 210 minutes (the temperature 25℃); the adsorption amount of Pd increased with the increasing of the temperature, higher temperature and high pH were both beneficial for the adsorption, and the process was endothermal.Effects of the temperature and flow rate on the dynamic adsorption had been examined. The results showed that lower flow rate and higher temperature were beneficial for the adsorption, and the suitable conditions were as follows: the flow rate 3ml/min, the pH 10, the temperature 40℃. The results of the column dynamic desorption experiments showed that employing lower flow rate, higher concentration a higher desorption efficiency could be obtained, and the suitable conditions for the desorption were the concentration 2%(mass percentage) HCl, the flow rate 3ml/min and the temperature 65℃. Effects of the flow rate and the initial palladium concentration on the adsorption breakthrough curve had also been investigated; the results indicated that with increasing the flow rate and the initial palladium concentration, the breakthrough time decreased, and the efficiency of the resin function groups and the adsorption efficiency of Pd also decreased.Freundlich isotherm was more suitable for describing the adsorption process, the thermodynamic study of the adsorption process showed that the palladium adsorption-ion exchange process is spontaneous and endothermal, and the entropy is positive. A sencond-order adsorption-ion exchange kinetic equation was developed for the process, and the equation parameters were estimated, results indicated that the particle diffusion was dominant step during the process of palladium adsorbing on the D113 resin.