Sorption of Eu(III) at feldspar/water interface: effects of pH, organic matter, counter ions, and temperature

Abstract

<jats:title>Abstract</jats:title><jats:p>The sorption of Eu(III) on potassium feldspar (K-feldspar) was studied under various physicochemical conditions such as pH, temperature, counter ions and organic matter. The results showed that the sorption of Eu(III) on K-feldspar significantly increased with the increase of pH, and high Eu(III) concentration can inhibit such immobility to some extent. The presence of humic acid (HA) can increase the sorption of Eu(III) on K-feldspar in low pH range; while inhibit to a large extent under alkaline conditions. It is very interesting that at pH ~6.5, high ionic strength can promote the sorption of Eu(III) on K-feldspar in the presence of HA. In contrast, Eu(III) sorption was restricted obviously by NaCl in the absence of HA. The sorption procedure was involved with ion exchange and/or outer-sphere complexation as well as inner-sphere complexation. The presence of F</jats:p>

Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique

“…Another possible explanation is the formation of hydrolyzed surface complexes, which may exhibit shorter lifetimes 40 . The formation of such hydrolyzed surface species is in good agreement with earlier studies of the sorption behavior of trivalent lanthanides and actinides on feldspars 11,12 . The additional long lifetime close to complete loss of hydration, indicates incorporation of Eu 3+ .…”

“…Over time, this reaction may lead to the incorporation of Eu 3+ into silica, often in the form of Eu 3+ -bearing colloidal silica. On alkali-feldspar a similar sorption behavior was reported with inner-sphere sorption starting at pH 4.5 (albite, Na-feldspar) or 5.5 (orthoclase, K-feldspar) 11,12 . At a pH of 6.0 the formation of a second species is observed on both feldspar end members, which was interpreted as hydrolysis of the first inner sphere sorption species.…”

“…With increasing pH (pH > 4.5) also the formation of inner sphere (IS) surface complexes on quartz 9,10 and feldspar 11 is expected. Regime III is most likely dominated by sorption on feldspar, where very similar sorption edges at pH ~ 6.5–7.5 have been observed for Eu 3+ previously 12 and sorption on quartz occurs slightly shifted to lower pH between pH 6.0 and 7.0 36 . Again it is not possible to distinguish potential contributions from micas and quartz.…”

CW EPR Investigation of Red‐Emitting CaS:Eu Phosphors: Rationalization of Local Electronic Structure

“…[28] The binding energies of the observed signals are comparable to those reported for Eu(OH) 3 , present at 1134.4 and 1164.2 eV for the 3d 5/2 and 3d 3/2 regions respectively. [29] The binding energies for Eu 2+ , the EPR-active state, are typically reported to be around 1125 and 1155 eV for the 3d 5/2 and 3d 3/2 core levels [30,31] and would be well removed from the observed spectral lines. We can therefore be confident that the XPS signals do not directly correspond to paramagnetic Eu 2+ (within the limits of detection).…”

Molecular-Level Speciation of Eu(III) Adsorbed on a Migmatized Gneiss As Determined Using μTRLFS

“…Crystalline rock is a possible host rock formation for nuclear waste repositories. Some countries have already decided to construct their disposal facility for highly radioactive nuclear waste in granite, , while others are considering crystalline rock in general as a preferred option. − Consequently, many studies have addressed the retention of relevant radionuclides on granite ,− and its components. − Such studies are complicated by the inherent heterogeneity of the material. They will contain at least the three most common main components (quartz, feldspar, and mica) to varying degrees and a plethora of additional minor mineral phases.…”