Speciation of Technetium in Sulfuric Acid/Hydrogen Sulfide Solutions

Abstract

The reaction between TcVII and H2S(g) in 12 M H2SO4 has been studied. This reaction produced a black solid and a brown supernate. The solid was analyzed by energy dispersive X-ray (EDX) and X-ray absorption fine structure (XAFS) spectroscopy and the results were consistent with the presence of Tc2S7. The speciation of technetium in the supernate was performed by UV/Visible and XAFS spectroscopy. Experiments showed that in 12 M H2SO4 an intermediate TcV sulfate complex was formed. Analysis indicated that the final complex present in solution was a polymeric species with a Tc-O-Tc core coordinated to sulfate ligands. Density Functional Theory (DFT) calculations showed that the proposed complexes were stable and that the theoretical structure was in good agreement with XAFS data

Technetium sulfide – formation kinetics, structure and particle speciation

“…Some important data on the Fe sulfide ores reducing Tc to Tc(IV) onto Tc environmental behavior was reported by the same authors [18]. The Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 6/1/15 1:35 PM results of [17][18][19] support in principle the evidence for the formulation of common technetium sulfide established by Lukens and co-workers [16] and confirmed in this work. We consider that the total data of the latter works provide a correct and important description of technetium polysulfide as a complex compound formed from water solutions by reaction of pertechnetate with sulfide source ores.…”

Technetium Stabilization in Low-Solubility Sulfide Phases: A Review

“…Only amorphous Tc 2 S 7 is obtained from the reaction of TcO 4 – with H 2 S­(g) in acidic solutions of HCl or H 2 SO 4 . Ferrier et al studied the speciation of Tc present in the aqueous supernatant from Tc-sulfur precipitates by the reaction between TcO 4 – and H 2 S­(g) in H 2 SO 4 , in order to elucidate Tc-sulfide dissolution mechanisms. A black solid and a brown supernatant were the products of the reaction, with ∼80% of the original Tc remaining in solution.…”

“…This Tc­(V) sulfate complex is reduced to a monomeric Tc­(IV) sulfate species (d), which polymerizes to form the dimeric Tc­(IV) sulfate complex (e). Reprinted with permission from ref . Copyright 2014 Wiley-VCH.…”

“…Proposed mechanism for the formation of the Tc(IV) species in 12 m H 2 SO 4 /H 2 S solution(Ferrier et al, 2014).…”

“…− with H 2 S(g) in acidic solutions of HCl or H 2 SO 4 . 13 Ferrier et al 86 studied the speciation of Tc present in the aqueous supernatant from Tcsulfur precipitates by the reaction between TcO 4…”