Proton affinities of pertechnetate (TcO₄⁻) and perrhenate (ReO₄⁻)

Abstract

Endeavoring to understand the basis for the difference between proton affinities of pertechnetate and perrhenate anions reveals complexity in a seemingly straightforward phenomenon.

Photocatalytic Reduction of Perrhenate and Pertechnetate in a Strongly Acidic Aqueous Solution

“…In conclusion, the results indicate that a portion of the amorphous phase in as-prepared TiO 2 is transformed into anatase nanocrystals. The confirmation of two phases (amorphous/anatase) can also be clearly observed in Figure S6B, which is consistent with our previous report . X-ray diffraction (XRD) patterns of the precursor fabricated by hydrolysis and then treated with calcination at 300 °C are shown in Figure S7.…”

“…99-Technetium ( 99 Tc), a weak β-emitting isotope with physiological toxicity, is produced by the fission of uranium and plutonium during the spent fuel reprocessing. , The stable and predominant chemical form exists in the heptavalent anion (pertechnetate, TcO 4 – ), and the oxyanion has high solubility and migration rate due to its negative charge in the environment, posing a serious ecological threat. , Conversant methods for TcO 4 – removal include solvent extraction, , physicochemical adsorption − or sequestration, , molecular recognition, , etc. One of the most commonly considered potential strategies for 99 Tc remediation is focused on TcO 4 – reduction. ,− The anion can be reduced from aqueous solution to sparingly soluble TcO 2 · n H 2 O, and then it can be separated for subsequent extraction.…”

“…1,2 The stable and predominant chemical form exists in the heptavalent anion (pertechnetate, TcO 4 − ), and the oxyanion has high solubility and migration rate due to its negative charge in the environment, posing a serious ecological threat. 3,4 Conversant methods for TcO 4 − removal include solvent extraction, 5,6 physicochemical adsorption 7−11 or sequestration, 12,13 molecular recognition, 5,14 etc. One of the most commonly considered potential strategies for 99 Tc remediation is focused on TcO 4 − reduction.…”

New Preparative Approach to Purer Technetium-99 Samples—Tetramethylammonium Pertechnetate: Deep Understanding and Application of Crystal Structure, Solubility, and Its Conversion to Technetium Zero Valent Matrix

“…According to current theories, no direct protonation of oxygen atoms in TcO 4 − anions occur. The formation of ionic pairs and more complicated associates with hydronium ions are formed in acid solutions [43][44][45]. Indeed, either two (the {TcO 4 •H 3 O + } ionic pair), or even four hydrogen bonds ({TcO 4 •H 7 O 3 + }) are formed upon the interaction of hydronium with pertechnetate (Figure 5): 24,2015 pertechnetate and nitrate anions, on the other hand.…”

“…According to current theories, no direct protonation of oxygen atoms in TcO4 − a occur. The formation of ionic pairs and more complicated associates with hydronium are formed in acid solutions [43][44][45]. Indeed, either two (the {TcO4•H3O + } ionic pa even four hydrogen bonds ({TcO4•H7O3 + }) are formed upon the interaction of hydro with pertechnetate (Figure 5): This phenomenon explains the impossibility of observing the "protonation" o technetate in optical and NMR spectra [46] up to 11 M HNO3, since the formation H-O-Tc bond does not occur by contrast with simple protonation.…”