N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) is a podand-type ligand with six nitrogen-donors and recognizes the slight difference in the softness between trivalent MA (minor actinides) and Ln (lanthanides). A copolymer gel of NIPA and a TPEN derivative, N,N,N',N'-tetrakis-(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN), was coated thinly on the pore surface of porous silica particles. The gel-coated silica was used as a chromatographic agent for the separation of MA and Ln in acidic solution.At first, we developed a new gel coating technique, which consists of several steps, such as the impregnation of porous silica with a monomer solution with TPPEN and NIPA by the interfacial tension, the rapid radical polymerization at 343K and the removal of unreacted monomers by water washing. When a monomer solution (10wt% TPPEN + 90wt% NIPA) was used, the pore volume was little reduced by the gel coating until the gel content of 10%. The average thickness of the gel film formed on the pore surface of porous silica particles (average diameter: 50�m, average pore diameter: 400 nm) was evaluated to be only 30 to 60 nm.Next, a chromatographic column (diameter and height : 1cm) packed with the gel-coated silica particles was prepared and the separation of Am(III) and Eu(III) were tested at 298K by two eluents of pH4 and pH2. The experimental results were shown in Fig.1. Sharp eluting peaks of Eu(III) and Am(III) were observed at the elution conditions of pH4 and pH2, respectively. These results suggest that the porous silica coated with thin firm of TPPEN-NIPA gel is suitable for the separation of MA and Ln and MA can be recovered easily by the small pH change from 4 to 2. Fig.1    Elution of Am(III) and Eu(III) at 298K

Chromatographic separation of Am(III) and Eu(III) by porous silica coated with TPPEN-NIPA gel

247th National Meeting (2014)

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