Bis[2-(dimethylamino)ethyl] diselenide was prepared by the reaction of Na 2 Se 2 with ClCH 2 CH 2 NMe 2 . 2-(Dimethylamino)ethaneselenolate complexes of palladium() of the type [PdCl(SeCH 2 CH 2 NMe 2) 2 ] 4 have been synthesized and characterized by elemental analysis, IR and NMR ( 1 H, 31 P, 77 Se) spectroscopy. The structures of orange 1 and of violet (λ max = 514 nm) 2c have been established by single crystal X-ray diffraction analyses. The trimer 1 contains a six-membered Pd 3 Se 3 ring in twist conformation. The thermal behaviour of three complexes, yielding Pd 17 Se 15 has been investigated.

The self-diffusion coefficients (SDCs) of Na(+), Cs(+), and Ba(2+) have been determined in Nafion-117 membrane having mixed cationic compositions. Membranes with different proportions of Na(+)-Cs(+), Cs(+)-Ba(2+), Na(+)-Ba(2+), and Ag(+)-Ba(2+) cations have been prepared by equilibrating with solutions containing different ratios of these cations. The SDCs of the cations (D(Na), D(Cs), D(Ba)) and the ionic compositions of the membrane have been determined using a radiotracer method. For the Na-Cs and Cs-Ba systems, the SDCs of the cations have been found to be independent of the ionic compositions of the membrane. In the case of the Na-Ba system, D(Na) does not change with ionic composition, while D(Ba) has been found to be strongly dependent on the ionic composition of the membrane and decreases continuously with increasing Na(+) content in the membrane. Similar results have also been obtained for D(Ba) in the case of the Ag-Ba system. The specific conductivities (κ(imp)) of the membrane in mixed cationic forms have also been obtained from ac impedance measurement and compared with that (κ(cal)) calculated from the SDC data. For the Na-Ba system, the increment of κ(imp) with increase in the Na(+) content of the membrane has been found to be parabolic, whereas for the Na-Cs system the increment is linear. The reason behind the different behaviors for different types of ionic systems has been qualitatively explained based on different transport pathways of the cations in the membrane.

Two types of Cs + ion-selective crown ether−Nafion composite membranes have been prepared. In one case, the dibenzo-21-crown-7 (DB21C7) has been incorporated uniformly in the Cs + form of Nafion-117 membrane in varying molar ratio with respect to Cs + , and in the other case, Cs + driven loading of DB21C7 has been confined (ion gating) to a very small thickness (25 μm) from one of the surfaces of the Nafion-117 membrane. The surface confinement of Cs + in the ion-gated membrane has been studied by energy dispersive X-ray spectroscopy and secondary ion mass spectrometry. The cation (Cs + /Na + ) transport properties of the membranes have been studied under application of electric field. In the uniformly crown-ether-loaded membranes (Cs-Naf-CR), the decrease in crown ether molar ratio has been found to increase the mobility of Cs + through the membrane at the cost of mutual cationic selectivity (Cs + over Na + ). On the other hand, enhanced selectivity of Cs + over Na + with significant cationic transport at room temperature has been obtained with the ion-gated membrane (Cs-H-Naf-CR). When applied to the simulated nuclear waste solution, selective transport of Cs + has also been obtained using this gated membrane even in the presence of very high Na + (Cs + :Na + = 1:1428) concentration in aqueous solution.

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The work describes a novel and cleaner approach of electrodriven selective transport of Cs from simulated nuclear waste solutions through cellulose tri acetate (CTA)/poly vinyl chloride (PVC) based polymer inclusion membrane. The electrodriven cation transport together with the use of highly Cs+ selective hexachlorinated derivative of cobalt bis dicarbollide, allows to achieve selective separation of Cs+ from high concentration of Na+ and other fission products in nuclear waste solutions. The transport selectivity has been studied using radiotracer technique as well as atomic emission spectroscopic technique. Transport studies using CTA based membrane have been carried out from neutral solution as well as 0.4 M HNO3, while that with PVC based membrane has been carried out from 3 M HNO3. High decontamination factor for Cs+ over Na+ has been obtained in all the cases. Experiment with simulated high level waste solution shows selective transport of Cs+ from most of other fission products also. Significantly fast Cs+ transport rate along with high selectivity is an interesting feature observed in this membrane. The current efficiency for Cs+ transport has been found to be ∼100%. The promising results show the possibility of using this kind of electrodriven membrane transport methods for nuclear waste treatment.