Adsorption behavior of trivalent americium and rare earth ions onto a macroporous silica-based isobutyl-BTP/SiO2-P adsorbent in nitric acid solution

To separate minor actinides from high level liquid waste (HLLW) of PUREX reprocessing, a silica-based macroporous isobutyl-BTP/SiO₂-P adsorbent was synthesized by impregnating isobutyl-BTP (2,6-di(5,6-diisobutyl-1,2,4-triazin-3-yl)pyridine) extractant into the macroporous SiO₂-P support with a mean diameter of 60 μm. A partitioning process using extraction chromatography for the treatment of HLLW was designed consisting five separation columns. As a partly work focused on isobutyl-BTP/SiO₂-P separation column, adsorption behavior of ²⁴¹Am and trivalent rare earth (RE) from simulated HLLW onto silica-based isobutyl-BTP/SiO₂-P adsorbent was investigated by batch method. Meanwhile, the chemical and radiolytic stabilities of isobutyl-BTP/SiO₂-P adsorbent against 0.01 M HNO₃ solution and γ-ray irradiation were studied. It was found that isobutyl-BTP/SiO₂-P adsorbent exhibited good adsorption selectivity for ²⁴¹Am over RE(III) in 0.01 M HNO₃ solution and showed weak or no adsorption affinity to light and middle RE(III) groups. In addition, in stability experiments, isobutyl-BTP adsorbent showed excellent stability against 0.01 M HNO₃ solution and γ-ray irradiation over 4 months contact time.