Sorption Properties of Aluminum Hexacyanoferrate for Platinum Group Elements

A sorbent, Aluminum hexacyanoferrate (AlHCF), has been developed for separating platinum group elements (PGMs) such as Pd, Ru, and Rh in high-level liquid waste generated from spent nuclear fuel reprocessing. The general sorption behavior of PGMs to AlHCF was measured. Without metal ions, substantial elution of AlHCF by nitric acid was observed. The single PGM sorption test revealed that Pd had fast kinetics and sorbed well to AlHCF, but the slow kinetics of Rh resulted in total dissolution of the sorbent. However, the reconstruction of the sorbent structure including Al and Fe, was observed. A competitive sorption experiment revealed that the coexistence of Pd stabilized the structure against nitric acid, and the percent sorption of Rh increased with the Pd concentration. Understanding the sorption and dissolution behavior of AlHCF will help improve its performance as a PGM sorbent.