Separation and Purification Technology 50 (2006) 278–281 Rapid communication Separation of trivalent actinides and lanthanides using a flat sheet supported liquid membrane containing Cyanex-301 as the carrier A. Bhattacharyya, P.K. Mohapatra, V.K. Manchanda ∗ Bhabha Atomic Research Centre, Radiochemistry Division, Trombay, Mumbai 400085, India Received 2 November 2005; received in revised form 24 November 2005; accepted 24 November 2005 Abstract The transport behaviour of trivalent actinides, viz. Am 3+ , Cm 3+ and lanthanides, viz. La 3+ , Eu 3+ , Tb 3+ , Ho 3+ , Yb 3+ and Lu 3+ across a polypropylene based supported liquid membrane containing Cyanex-301 (bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid) in n-dodecane as the carrier was investigated. The transport rates were in accord with their distribution data as seen from the solvent extraction studies. The trivalent actinides Am 3+ and Cm 3+ could be quantitatively separated from the lanthanides by this membrane based method in 4 and 20 h, respectively, with separation factor values in the range 108–4466. © 2005 Elsevier B.V. All rights reserved. Keywords: Cyanex-301; Lanthanide–actinide separation; Supported liquid membrane 1. Introduction High level nuclear waste management with minimum adverse impact on the environment is perhaps the key to the success of the closed nuclear fuel cycle. Use of borosilicate as the glass matrix is the current practice for the containment of the long- lived actinides and fission products. However, finite leach rates and possible deformation and failures necessitate periodic mon- itoring of these immobilized waste blocks. The radionuclides responsible for the deformation and failure of the glass matrix are some of the fission products, viz. 137 Cs, 90 Sr, etc. They are much shorter lived as compared to the minor actinides ( 241 Am, 244 Cm, etc.). The actinide partitioning is a strategy to separate minor actinides from the fission products [1]. Long term surveil- lance of the proposed vitrified waste blocks can be alleviated if actinide partitioning is done effectively. Actinide partitioning cannot separate the trivalent actinides and lanthanides due to their similar charge and chemical behaviour. In the proposed ‘Partitioning & Transmutation’ strategy, the separation of triva- lent lanthanides and actinides is a pre-requisite [2]. The presence of lanthanides, which act as neutron poisons due to their large absorption cross sections, is detrimental to an effective ‘burn- ing’ of actinides in high flux reactors. There is, therefore, a ∗ Corresponding author. Fax: +91 22 25505151. E-mail address: vkm@barc.ernet.in (V.K. Manchanda). need to separate trivalent lanthanides from the trivalent actinides prior to the transmutation reaction. It is desirable, therefore, to develop suitable complexing agents which can selectively com- plex with either of these two groups of elements from their mixtures. Co-ordination chemists have been focusing on the development of complexing ligands with soft donor atoms like N and S to exploit the increased covalent interaction with f- orbitals of actinide ions vis-` a-vis lanthanide ions which may provide the opportunity for the successful Ln/An separation. Soft donor extractants such as Cyanex-301 (bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid, Fig. 1(a)) are found to be quite promising for this purpose [3,4]. However, the large volume of toxic organic waste arising from the degradation of the thio-compounds can be avoided if the ligand inventory can be reduced significantly while maintaining the separation effi- ciency. Liquid membrane based methods, therefore, become a viable option. The high selectivity of Cyanex-301 for trivalent actinides makes it one of the most promising extractants to be explored as carrier for liquid membrane studies for lanthanides–actinides separation. Hoshi et al. have investigated the transport behaviour of Am 3+ and Eu 3+ through PTFE membranes using Cyanex-301 in kerosene–octanol mixture as the carrier [5]. However, they have observed relatively slow transport rates and poor decon- tamination factors. In the present work, the transport behaviour of several trivalent lanthanides, viz. La 3+ , Eu 3+ , Tb 3+ , Ho 3+ , Yb 3+ , Lu 3+ and actinides, viz. Am 3+ , Cm 3+ was investigated 1383-5866/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2005.11.023