Rapid and reliable assaying of Tc-99 in sediment samples with novel MTPN polymeric resin.

The paper describes a new method for the rapid determination of Technetium (Tc) in sediment samples using solid-phase extraction chromatography (SPEC) with a novel methyl triphenyl phosphoniumnitrate (MTPN) resin. The effectiveness of the resin in selectively recovering Tc was evaluated in both batch and column mode and exploited for rapid analysis of 'Tc'. The procedure involves the acid digestion of samples, pre-concentration of fission products in supernatant and co-precipitation of actinides with Fe(OH)3, followed by selective recovery of Tc by SPEC using a column filled with MTPN resin. The recovered Tc was then radiometrically assayed using beta counting. The method was validated using IAEA certified reference materials and was found to provide reliable and reproducible results for the activity concentration of Tc-99 in sediment samples within 24 h.

Evaluation of BenzoDODA grafted polymeric resin for rapid and reliable assaying of plutonium in sediment samples.

The paper reports a new rapid radioanalytical procedure for the determination of plutonium (Pu) in sediments by solid phase extraction chromatography (SPEC) using Bis-(2-ethylhexyl) carbamoyl methoxy phenoxy-bis-(2-ethylhexyl) grafted resin, abbreviated as Benzodioxodiamide (BenzoDODA) grafted resin. The resin was synthesized and evaluated for its sorption behaviour towards Pu in batch and column mode to determine its efficacy for selective recovery of Pu from sediment samples. The analytical procedure was based on the radiochemical separation of samples by acid digestion, followed by preconcentration of actinides by co-precipitation with Fe(OH)3 and finally selective recovery of Pu by SPEC using a column filled with BenzoDODA grafted resin. Pu was then radiometrically assayed by preparing alpha disc sources with electro-deposition followed by alpha spectrometry. The method was further validated with IAEA reference materials. This method gives reliable and reproducible results for the activity concentration of Pu in sediment samples within 24 h.

BenzoDODA grafted polymeric resin-Plutonium selective solid sorbent.

A new ligand grafted polymeric resin (BenzoDODA SDVB) was synthesized by covalently attaching plutonium selective ligand (BenzoDODA) on to styrene divinyl benzene (SDVB) polymer matrix. BenzoDODA SDVB resin was evaluated for separation and recovery of plutonium(IV) from nitric acid medium. Sorption of Pu(IV) was found to decrease with the increase in nitric acid concentration, with very small sorption above 7.0M HNO3. Sorption kinetics was fast enough to achieve the equilibrium within 60min of contact where the kinetic data fitted well to pseudo-second-order model. Sorption isotherm data fitted well to Langmuir model suggesting chemical interaction between the BenzoDODA moiety and plutonium(IV) ions. Sorption studies with some of representative radionuclides of high level waste showed that BenzoDODA SDVB is selective and therefore could be a promising solid sorbent for separation and recovery of plutonium. Further, the theoretical calculations done on BenzoDODA SDVB resin suggested Pu(NO3)4·BenzoDODA (1:1) sorbed complex conformed to generally observed square antiprism geometry of the plutonium complexes, with contributions from oxygen atoms of four nitrate ions as well as from four oxygen atoms present in BenzoDODA (two phenolic ether oxygen atoms and two carbonyl oxygen atoms of amidic moiety).

Investigation of the extraction complexes of palladium(II) with novel thiodiglycolamide and dithiodiglycolamide ligands by EXAFS and computational methods.

The structure of the extraction complexes of palladium(II) with novel ligands, namely, N,N,N',N'-tetra-(2-ethylhexyl) thiodiglycolamide (T(2EH)TDGA) and N,N,N',N'-tetra-(2-ethylhexyl) dithiodiglycolamide (DTDGA), have been determined by extended X-ray absorption fine structure spectroscopy (EXAFS). The interpretation of the EXAFS data is well supported by theoretical calculations of the complex geometry based on density functional theory (DFT). T(2EH)TDGA, having one thioetheric 'S' atom, forms a square planar complex with the Pd(II) ion, exhibiting 2: 1stoichiometry with one sulphur atom and one carbonyl oxygen atom from each T(2EH)TDGA molecule interacting with Pd(II) at distances of 2.24 and 2.04 Å, respectively. On the other hand, DTDGA, having two 'S' atoms in addition to two carbonyl groups, forms a square planar complex with Pd(II), exhibiting 1: 1stoichiometry, wherein both the sulphur atoms and the carbonyl oxygen of DTDGA interact with Pd(II) at distances of 2.29 and 2.05 Å, respectively. The slight distortion from the perfect square planar geometry could be attributed to the steric hindrance imposed by the bulky alkyl group of the amidic moieties. DFT calculations for the Pd-ligand complexes show that the Pd(II)-DTDGA complex with 1: 1stoichiometry is energetically more stable than the Pd(II)-T(2EH)TDGA complex with 1: 2stoichiometry. Among the two possible Pd(II)-T(2EH)TDGA complex geometries, the cis configuration appears more favorable. The methodology of fitting the EXAFS data has been validated by fitting the EXAFS data of a Pd(II)-aquo complex which showed square planar geometry with two axial water molecules constituting the secondary hydration sphere.

Facilitated transport of Pd(II) through a supported liquid membrane (SLM) containing N,N,N',N'-tetra-(2-ethylhexyl) thiodiglycolamide T(2EH)TDGA: a novel carrier.

A novel carrier, N,N,N',N'-tetra-(2-ethylhexyl) thiodiglycolamide, T(2EH)TDGA has been studied for transport of Pd(II) from nitric acid medium across a supported liquid membrane (SLM). Pd(II) was found to be almost quantitatively transported (≈ 99.9%) within 2h from 3.0M HNO(3) medium using 0.05 M T(2EH)TDGA in n-dodecane as carrier and 0.01 M thiourea in 0.2M HNO(3) as strippant. Pd(II) transport was also studied against various parameters like feed acidity, carrier concentration, membrane pore size, etc. Palladium transport was found to be diffusion controlled and the diffusion co-efficient value was found to be 3.56 × 10(-5)cm(2)/s. Selectivity of T(2EH)TDGA for palladium over other fission products was found to be quite high, with the separation factors for Pd, with respect to different fission products being >10(3). With respect to leaching out of carrier from the membrane support, the membrane was found to be stable for six consecutive cycles. Thus, T(2EH)TDGA can be used as an efficient carrier of Pd(II) from nitric acid medium.

Extractive spectrophotometric determination of palladium with N,N,N',N'-tetra(2-ethylhexyl)-thiodiglycolamide T(2EH)TDGA.

A precise, sensitive and selective method for the spectrophotometric determination of palladium (II) using N,N,N',N'-tetra(2-ethylhexyl) thiodiglycolamide T(2EH)TDGA as an extractant is described. Palladium (II) forms yellow colored complex with T(2EH)TDGA which exhibits an absorption maximum at ∼ 300 nm. The colored complex obeys Beer's law in the concentration range 1.0-15.0 µg ml(-1) of palladium with a molar absorptivity of 1.29 × 10(5)M(-1)cm(-1). The effects of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of palladium. The precision of the method has been evaluated and the relative standard deviation has been found to be less than 0.5%. The method has been successfully applied to the determination of palladium in simulated high level liquid waste (SHLW) solution.