Separation of actinides(III) from lanthanides(III) in simulated nuclear waste streams using 6,6 '-bis-(5,6-dipentyl-[1,2,4]triazin-3-yl)-[2,2 ']bipyridinyl (C5-BTBP) in cyclohexanone

An extraction system comprising 6,6'-bis-(5,6-dipentyl-[1,2,4] triazin-3-yl)[ 2,2'] bipyridinyl (C5-BTBP) dissolved in cyclohexanone was investigated. The main purpose of this investigation was to extract and separate actinides(III) from lanthanides(III), both of which are present in the waste from the reprocessing of spent nuclear fuel. The system studied showed high distribution ratios for the actinides( III) and a high separation factor between actinides and lanthanides (SFAm/Eu around 150). The extraction kinetics were fast with equilibrium being reached in 5 minutes. The effects of temperature on the extraction and the stoichiometry of the extracted complex were investigated. The extraction of californium( III) was studied and it was found that the BTBP molecule has a higher affinity for californium than for americium (SFCf/Am around 4). This system could be used to separate actinides( III) from lanthanide fission products with high efficiency, if used in conjunction with a pre-equilibrium step.