Journal of Membrane Science 375 (2011) 141–149 Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Evaluation of a novel tripodal diglycolamide for actinide extraction: Solvent extraction and SLM transport studies P.K. Mohapatra a,∗ , M. Iqbal b , D.R. Raut a , W. Verboom b , J. Huskens b , V.K. Manchanda a a Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India b Laboratory of Molecular Nanofabrication, MESA + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands article info Article history: Received 19 January 2011 Received in revised form 16 March 2011 Accepted 17 March 2011 Available online 29 March 2011 Keywords: Tripodal diglycolamide Actinides TODGA Solvent extraction Liquid membrane abstract A novel tripodal diglycolamide (T-DGA) extractant in a diluent mixture (10:1 n-dodecane–iso-decanol) was evaluated for the extraction of actinide ions such as UO 2 2+ , Np(IV), Pu(IV), and Am(III) and fission product element ions such as Cs + and Sr 2+ from acidic feed solutions. Conditions for quantitative extrac- tion and stripping were found out for the actinide ions other than UO 2 2+ which is poorly extracted. Solvent extraction studies were carried out at varying concentrations of the extractant and nitric acid using Am(III) and were compared with the results obtained with TODGA (N,N,N ′ ,N ′ -tetraoctyldiglycolamide), a repre- sentative diglycolamide extractant proposed for actinide partitioning. The extracted species was found out to be Am(NO 3 ) 3 ·2T-DGA (o) at higher T-DGA concentrations, while mixed 1:1 and 1:2 species were observed at lower T-DGA concentrations. The prevalence of 1:2 species in the present case as compared to the 1:1 species reported in a similar system was attributed to the low dielectric constant diluent medium used in the present study. Supported liquid membrane studies were also carried out using the T-DGA under varying feed acidities, carrier extractant concentration and compared with TODGA under identical conditions. The transport rates are dependent on the strippant used in the receiver phase and a 0.01 M EDTA solution (pH 3.0) was found to yield quantitative transport of Am(III) using T-DGA as compared to dilute nitric acid, which was efficiently used for the TODGA system in an earlier study. The transport efficiency of the carrier solvent system was Am(III) > Pu(IV) ≫ Np(IV) > UO 2 2+ . The diffusion parameters were calculated for the T-DGA system and compared with the experimentally determined parameters. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Separation of minor actinides from acidic feed solutions is of paramount importance from the point of view of safe management of radioactive waste for the mitigation of their long term hazards [1,2]. Moreover, environmental sample analysis for minor actinide contaminants such as 241,243 Am and 244,245 Cm also involves their selective separation from acidic feeds. Extractants such as CMPO (carbamoylmethyl phosphine oxide) and tetraalkylmalonamides such as DMDOHEMA (N,N ′ -dimethyl-N,N ′ -dioctylhexylethoxy mal- Abbreviations: CMPO, carbamoyl methyl phosphine oxide; DCC, N ′ ,N ′ - dicyclohexylcarbodiimide; DGA, diglycolamide; DMDOHEMA, N,N ′ -dimethyl-N,N ′ - dioctyl hexylethoxy malonamide; EDTA, ethylene diamine-N,N,N ′ ,N ′ -tetraacetic acid; HLW, high level waste; HOBT, 1-hydroxybenzotriazole; PUREX, Plutonium Uranium Reduction Extraction; PTFE, polytetrafluoroethylene; SLM, supported liq- uid membrane; T-DGA, tripodal diglycolamide; TODGA, tetraoctyl diglycolamide; TRUEX, Trans Uranium Element Extraction. ∗ Corresponding author. Tel.: +91 22 25594576; fax: +91 22 25505151. E-mail addresses: mpatra@barc.gov.in, mpatra@magnum.barc.ernet.in (P.K. Mohapatra). onamide) have been found to be promising for the extraction of trivalent minor actinides from acidic feed solutions [3–5]. How- ever, these reagents also extract other actinide ions such as Pu 4+ and UO 2 2+ from acidic feed solutions. The usual extraction trend has been Pu 4+ > UO 2 2+ > Am 3+ , which is in line with their decreasing ionic potential and complexing ability [6]. These extractants, how- ever, suffer from serious shortcomings such as, use of CMPO leads to the generation of large volumes of secondary wastes, while the malonamide based extractants, though having advantages such as complete incinerability and innocuous degradation products, yield modest distribution coefficient values and are prone to third phase formation [3]. On the other hand, diglycolamide (DGA) extractants have been found to be promising due to their excellent ability to extract trivalent actinides such as Am 3+ from nitric acid medium without any significant disadvantages mentioned above [7,8]. Out of the DGA-based extractants, TODGA (N,N,N ′ ,N ′ -tetraoctyl diglyco- lamide, Fig. 1(a)) displays an unusual extraction behaviour toward the actinides as the trivalent ions are extracted to a much greater extent than the tetra- and hexavalent actinide ions [9,10]. This has been attributed to the aggregation behaviour of TODGA in non- polar diluents such as n-dodecane [11]. The formation of reverse 0376-7388/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2011.03.042