Exchange Capacity of Polysiloxane Ion Exchangers Modified with Dithiooxamide Groups with Respect to Silver(I), Platinum(IV), and Palladium(II)

Abstract

A polysiloxane with attached groups of rubeanic acid is proposed for the extraction of silver(I), platinum(IV) and palladium(II) from dilute aqueous systems. The sorbent is synthesized for the first time via modern sol–gel technology and has a high degree of surface modification; the concentration of the attached dithiooxamide groups is 0.90 mmol/g. Isotherms of the sorption of silver(I), platinum(IV), and palladium(II) from individual solutions are constructed. The curves are mathematically processed with the Langmuir, Freundlich, Redlich–Peterson, Langmuir–Freundlich, and Toth equations, so exchange capacity values are determined for the modified polysiloxane. The sorbent has good capacitive characteristics and can be used to accumulate large amounts of noble metal ions.