Stability of europium(II) in aqueous nitrate media

TY - JOUR

T1 - Stability of europium(II) in aqueous nitrate media

AU - Van de Voorde, Michiel

AU - Geboes, Bart

AU - Van Hecke, Karen

AU - Cardinaels, Thomas

AU - Vander Hoogerstraete, Tom

AU - Binnemans, Koen

N1 - Score=10

PY - 2019/9/5

Y1 - 2019/9/5

N2 - In the lanthanide series, Eu(III) is most easily reduced to its divalent state. Reduction of Eu(III) has been studied extensively in aqueous media that are insensitive to reducing conditions. Recently, it has been reported that reduction of Eu(III) is also feasible in aqueous nitrate solutions and that Eu(II) remained sufficiently stable in these media to conduct separation experiments. However, additional fundamental research on the reduction efficiency of Eu(III) and stability of Eu(II) in these media has not been reported yet. In this paper, cyclic voltammetry, magnetic susceptibility measurements, UV-vis absorption spectroscopy and X-ray absorption near edge structure (XANES) spectroscopy were used to gain more insights into the reduction of Eu(III) in aqueous nitrate media. Within the parameters used in this work, near-quantitative reduction of Eu(III) could be achieved within 120 min in highly concentrated nitrate salt solutions, using both chemical and electrochemical reduction techniques. Moreover, Eu(II) was remarkably stable in these solutions, showing just a small percentage of back-oxidation after 5 h in a sealed measurement cell.

AB - In the lanthanide series, Eu(III) is most easily reduced to its divalent state. Reduction of Eu(III) has been studied extensively in aqueous media that are insensitive to reducing conditions. Recently, it has been reported that reduction of Eu(III) is also feasible in aqueous nitrate solutions and that Eu(II) remained sufficiently stable in these media to conduct separation experiments. However, additional fundamental research on the reduction efficiency of Eu(III) and stability of Eu(II) in these media has not been reported yet. In this paper, cyclic voltammetry, magnetic susceptibility measurements, UV-vis absorption spectroscopy and X-ray absorption near edge structure (XANES) spectroscopy were used to gain more insights into the reduction of Eu(III) in aqueous nitrate media. Within the parameters used in this work, near-quantitative reduction of Eu(III) could be achieved within 120 min in highly concentrated nitrate salt solutions, using both chemical and electrochemical reduction techniques. Moreover, Eu(II) was remarkably stable in these solutions, showing just a small percentage of back-oxidation after 5 h in a sealed measurement cell.

KW - Lanthanide

KW - Electrochemistry

KW - Reduction

KW - XANES

KW - Cyclic voltammetry

KW - Divalent europium

UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/35499785

U2 - 10.1039/c9dt03139a

DO - 10.1039/c9dt03139a

M3 - Article

VL - 48

SP - 14758

EP - 14768

JO - Dalton Transactions

JF - Dalton Transactions

SN - 0300-9246

IS - 39

ER -