Palladium (II) sorption from nitric acid solutions by silica modified with amino groups

Abstract

Sorption of Pd(II), Ag(I) and Cu(II) from nitric acid solutions by silica chemically modified with γ-aminopropyltriethoxysilane was studied. Based on the research of solid phase by IR & X-ray photoelectron spectroscopy, as well as thermogravimetry, it was suggested that palladium sorption from nitric acid solutions includes the following processes: coordination of palladium ions to nitrogen atoms of the functional group, reaction of palladium ions with the silica matrix and formation of polynuclear complexes. It was also proposed to use 5 % thiourea solution in 0,1 M HCl as a palladium desorbent. It was determined that the time of constant sorption rate settling in static conditions was (min): for Ag(I) – 10, for Cu(II) – 20, Pd(II) – 30. The row of ion sorption (imbibition) from 2 M HNO 3 is as follows: А Ag(I) > А Pd(II) >> А Cu(II) . At the same time, silver ions are not adsorbed from solutions with a concentration of HNO 3 < 1 M thus creating prerequisites for separation of ions.