Sorption behaviour of pertechnetate on oxidized and reduced surface of activated carbon

Sorption of pertechnetate anion by cation modified bentonites

“…In both cases a soprtion of 80-90% was observed. Almost 100% soprtion was achieved after 30 min on activated carbon [12]. On Sn-apatite > 92% removal of technetium was observed [20].…”

“…There are also other adsorbents in the literature such as activated carbon [11,12], layered double hydroxide (LDHs) [13], alumina and goethite [14], and there are the clay minerals which play an important role in the environment because by removing cations and anions either through ion exchange, adsorption and precipitation, or all these combined, they can act as natural decontaminating agents of numerous pollutants. Bentonite as geological and engineering barrier is present to isolate the radioactive waste deposited in underground disposal and the environment.…”

Fusion-Based Neutron Generator Production of Tc-99m and Tc-101: A Prospective Avenue to Technetium Theranostics

“…The [TcO 4 ] − anion is considered a relatively large anion with a low charge density, a low degree of hydration [ 48 ], and exhibits chaotropic character in regards to the Hofmeister series; it is found as the predominant form of Tc under oxidising conditions and across a range of pHs in most non-complexing media. The uptake of Tc on AC occurs at all pHs, however, at acidic pHs below the zero-point-charge of AC, whereby surface species become protonated and the surface becomes positively charged, the kinetics of Tc sorption are significantly enhanced [ 47 , 49 , 50 ]. Adsorption values greater than 99% [TcO 4 ] − (~1 MBq 99m Tc) onto AC within 1-min have been reported in the pH range 2–3 where maximum distribution coefficient ( K d ) values were measured [ 51 ].…”

“…Adsorption values greater than 99% [TcO 4 ] − (~1 MBq 99m Tc) onto AC within 1-min have been reported in the pH range 2–3 where maximum distribution coefficient ( K d ) values were measured [ 51 ]. The primary contributing surface species are said to be carboxylic, carbonyl, laconic, and phenolic groups, where R–C=O and R–C–OH moieties serve as potential binding sites for [TcO 4 ] − [ 47 , 49 , 50 ] Measured K d greater than ~10 5 for Tc uptake onto AC under acidic pHs have been reported [ 41 , 47 , 51 ]. Even in the presence of competing anions, such as [SO 4 ] 2 − , [PO 4 ] 2 − , [F] − , [Br] − , [Cl] − , and [NO 3 ] − does this this phenomenon readily occur, although higher concentrations (i.e., [NO 3 ] − (> 0.1 mM), [SO 4 ] 2− and [PO 4 ] 2− (> 1.0 mM), [Cl] − and [Br] − (> 10 mM)) can be somewhat inhibiting [ 40 , 42 , 49 , 50 ].…”

“…Adsorption values greater than 99% [TcO 4 ] − (~1 MBq 99m Tc) onto AC within 1-min have been reported in the pH range 2-3 where maximum distribution coefficient (K d ) values were measured [51]. The primary contributing surface species are said to be carboxylic, carbonyl, laconic, and phenolic groups, where R-C=O and R-C-OH moieties serve as potential binding sites for [TcO 4 ] − [47,49,50] Measured K d greater than~10 5 for Tc uptake onto AC under acidic pHs have been reported [41,47,51] on AC [49,50]. For comparison, the change in free energy of adsorption of different anions onto activated carbon was determined to be:…”