Selective separation of actinyl(V,VI) cations from aqueous solutions by Chelex-100

Abstract

Actinides / Selective separation / Guest-host interactions / Chelex-100 resin / Aqueous solutionSummary. Experimental studies on the selectivity of Chelex-100 resin for the separation of actinide cations at different oxidation states (III, IV, V and VI) from aqueous solution have shown that Chelex-100 presents increased selectivity for actinyl cations at near neutral pH (pH ∼ 4.5). The effect of salinity on the chemical recovery indicates that the increased selectivity could be attributed to the formation of complexes with specific interactions and the pH area, in which the formation of the respective complexes is favored, indicates the occurrence of guest-host interactions. The specific interaction of Chelex-100 with actinyl cations could be of particular interest not only for the separation and preconcentration of uranium from natural waters prior its analysis but also for the recovery of uranium from seawater on a large scale.

Sorption Characteristics and Chromatographic Separation of 90Y3+ from 90Sr2+ from Aqueous Media by Chelex-100 (Anion Ion Exchange) Packed Column

“…Representative plot of K d versus of pH of Y 3+ and Sr 2+ sorption onto Chelex-100 (anion ion exchanger) from aqueous DTPA solution (1.0 × 10 −3 M) after 60 min shaking time at 25 ± 0.1°C is shown in Figure 2 . The observed behavior in Figure 2 is most likely attributed to the possible formation of nonpolar complex species of Y 3+ species (YCl 6 ) 3− with the available iminodiacetate moieties of the chelating Chelex 100 sorbent at pH ≤ 3 (pK a1 = 3.2) [ 40 , 42 , 43 ]. At low pH (pH ≤ 3), the possible interaction between the formed complex anion of yttrium (YCl 6 ) 3− and the protonated iminodiacteate moieties of the chelating Chelex−100 anion ion exchanger by forming ternary complex ion associate may also contributed in the observed trend at low pH ≤ 3 [ 42 , 43 ].…”

“…The observed behavior in Figure 2 is most likely attributed to the possible formation of nonpolar complex species of Y 3+ species (YCl 6 ) 3− with the available iminodiacetate moieties of the chelating Chelex 100 sorbent at pH ≤ 3 (pK a1 = 3.2) [ 40 , 42 , 43 ]. At low pH (pH ≤ 3), the possible interaction between the formed complex anion of yttrium (YCl 6 ) 3− and the protonated iminodiacteate moieties of the chelating Chelex−100 anion ion exchanger by forming ternary complex ion associate may also contributed in the observed trend at low pH ≤ 3 [ 42 , 43 ]. On the other hand, at pH above pH 3, one of the two carboxylic acids of the iminodiacetate moiety is deprotonated carrying a negative charge which attracts other positive cation present in extraction media, e.g., Na + (introduced from pH adjustment by diluted NaOH which compete effectively with Y 3+ because of their considerably higher concentration in solution [ 42 ].…”

“…At low pH (pH ≤ 3), the possible interaction between the formed complex anion of yttrium (YCl 6 ) 3− and the protonated iminodiacteate moieties of the chelating Chelex−100 anion ion exchanger by forming ternary complex ion associate may also contributed in the observed trend at low pH ≤ 3 [ 42 , 43 ]. On the other hand, at pH above pH 3, one of the two carboxylic acids of the iminodiacetate moiety is deprotonated carrying a negative charge which attracts other positive cation present in extraction media, e.g., Na + (introduced from pH adjustment by diluted NaOH which compete effectively with Y 3+ because of their considerably higher concentration in solution [ 42 ]. The fact that, in acidic solutions, the N atom of the iminodiactic group retaining free electron pair is protonated, hence the resin is most likely can acts as weakly basic anion exchanger [ 43 ].…”

“…In the irradiated product, the impurities were then checked as reported earlier [ 10 ]. The specific activity ( S ) was then computed as reported earlier [ 40 – 42 ]. The purity of irradiated 90 YCl 3 was also confirmed from the decay shape over 3 half-lives ( t 1/2 ) period at neutron flux density of 1.3 × 10 13 neutrons/cm 2 /s as reported [ 44 , 45 ].…”

Uranium levels in Cypriot groundwater samples determined by ICP-MS and α-spectroscopy

“…Generally, 500 ml of each groundwater sample were pre-treated by cation-exchange as described elsewhere (Pashalidis and Tsertos, 2004;Killiari and Pashalidis, 2010). This pre-analytical procedure, which is selective for uranium (Killiari and Pashalidis, 2012), was carried out in parallel for every sample. Alpha-spectroscopic analysis was performed using a highresolution a-spectrometer (Alpha Analyst Integrated Alpha Spectrometer, Canberra) equipped with semiconductor detectors.…”