Affinity of four different extraction chromatographic resin for Pd and Ag: Toward efficient separation of Pd from Ag

In this study, the affinity of four extraction chromatographic resins from TrisKem International (TK200 Resin, Ni Resin, LN Resin, and TBP Resin) for retaining Pd and Ag in nitric and hydrochloric acid medium of various molarities was systematically investigated. Batch experiments were performed in which the resins were contacted with Pd and Ag solutions prepared in nitric and hydrochloric acids of different molarities. Affinity of specific resin for Pd and Ag was assessed with the help of distribution coefficients (K_d), defined as the ratio of the concentration of a specific element between resin and solution under equilibrium conditions, as a function of nitric and hydrochloric acid concentration. The results provided fundamental insight into behaviour of Pd and Ag in connection with different resin under varying chemical conditions and enabled design of optimum Pd and Ag column separation protocol. Among the resins investigated, Ni Resin and TK200 Resin exhibited the most favourable selectivity and separation performance, allowing efficient and reproducible Pd-Ag separation with high recoveries. For Ni Resin, the overall recovery was 92% for Pd and 98% for Ag, with a Pd separation factor of 2500±300. For TK200 Resin, the overall recovery was 89% for Pd and 98% for Ag, with a Pd separation factor of 770±80. However, an additional separation step would be required to achieve a higher separation factor when using TK200 Resin.