“…In 1 M H 2 SO 4 , Pu(IV) predominantly exists as a quadra sulphate complex (QSC) ions [Pu(SO 4 ) 4 (H 2 O) 4 ] -4 . 4,26 Therefore the diffusion coefficient of heavier QSC ions (about 700 amu) is pretty small. The overall observations suggest that the diffusing QSC ions are reduced at the platinum electrode in 1M H 2 SO 4 through quasi-reversible (a = 0.39) single electron transfer process.…”
“…In 1 M H 2 SO 4 , Pu(IV) predominantly exists as a quadra sulphate complex (QSC) ions [Pu(SO 4 ) 4 (H 2 O) 4 ] -4 . 4,26 Therefore the diffusion coefficient of heavier QSC ions (about 700 amu) is pretty small. The overall observations suggest that the diffusing QSC ions are reduced at the platinum electrode in 1M H 2 SO 4 through quasi-reversible (a = 0.39) single electron transfer process.…”
“…In the case of Am(III), an extraction competition between Am(III) and HNO 3 leads to a decrease of the K d values of Am for a nitric acid concentration over 4 M . The chemistry of Pu(IV) is more complex since Lipis et al showed that at least six Pu(IV) complexes can exist as a function of the acidity (Figure ) 6 7 Pu(IV) speciation established by Lipis et al …”
Section: Resultsmentioning
confidence: 99%
“…The chemistry of Pu(IV) is more complex since Lipis et al showed that at least six Pu(IV) complexes can exist as a function of the acidity (Figure ) 6 7 Pu(IV) speciation established by Lipis et al …”
Hybrid materials with complexing properties toward lanthanides(III), americium(III), and plutonium(IV) are described. These new silica-based materials, containing malonamide ligands, have been prepared by sol-gel hydrolysis and condensation of a silylated tetraethylmalonamide in the presence of tetraethoxysilane (TEOS). A family of these hybrid materials was obtained by varying the amount of TEOS, the catalyst, and the R w ratio (amount of water added per Si-O bonds). The porous hybrids exhibited BET surface areas up to 300 m 2 g -1 with the average pore diameter ranging from 30 to 90 Å. The new hybrids were used as solid phase extractants in batch experiments for the extraction of americium and plutonium from high-level liquid wastes. The hybrids were shown to be highly efficient materials in solid-liquid extraction, exhibiting distribution coefficients up to 10 4 and loading capacities up to 0.46 mequiv/g. They compared favorably to related silica-based material containing malonamide immobilized by classical techniques. The sol-gel approach allows one to adjust the ligand loading and to achieve some control and some tuning of the ligand environment since the oxide matrix is built around the complexing moieties. The use of templating techniques was also studied to enhance the extracting properties.
“…The nitrate ion complex of Pu(IV) in HNO 3 solutions may be expressed as Pu(NO 3 ) n 4−n (n = 1 − 6). Lipis et al [8] plotted the molar extinction coefficients evaluated at selected Pu(IV) absorption peaks as a function of HNO 3 concentration and used them to determine the nitrate coordination number of Pu(IV). The range of HNO 3 concentration where each of the complexes are stable was found to be as follows: Pu(NO 3 ) 3+ , <1.5 mol/dm 3 is in general agreement with the conclusions of Ryan [9], who studied the nitrate complex of Pu(IV) by ion exchange and spectrophotometric methods.…”
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