Preparation of a Macroporous Silica-Based Pyridine Impregnated Material and Its Adsorption for Palladium

A macroporous silica-based 2,6-bis(5,6-di(iso-hexyl)-1,2,4-triazine-3-yl)pyridine (BDIHTP) multinitrogen molecular recognition material, BDIHTP/SiO(2)-P, was prepared. It was performed through impregnation and immobilization of BDIHTP into the pores of the macroporous SiO(2)-P particle support with a mean diameter of 50 mu m. The adsorption of some typical alkali metal and alkaline earths Cs(I), Na(I), K(I), Rb(I), Sr(II), and Ba(II), as well as Pd(II), a representative of precious metals, contained in highly active liquid waste (HLW), onto the BDIHTP/SiO(2)-P material was investigated at 298 K. It was carried out by examining the effects of contact time and the HNO(3) concentration in the range 0.3-5.0 M. BDIHTP/SiO(2)-P showed excellent adsorption ability and high selectivity for Pd(II) over all the tested metals, which had weak or almost no adsorption. It was attributed to the strong chemical complexation of Pd(II), a soft Lewis acid and an electron-pair acceptor, with nitrogen inside BDIHTP, a soft Lewis base and an electron-pair donor. On the basis of the related results, the chromatographic separation of Pd(II) from 1.0 M HNO(3) solution containing the tested metals was performed by BDIHTP/SiO(2)-P packed column. Pd(II) was effectively eluted with 0.2 M thiourea and separated from the others. The results are very beneficial to building an effective partitioning of minor actinides and Pd(II) together from HLW by the BDIHTP/SiO(2)-P materials.