Entrapment of molecular iodine produced in nuclear industry, with

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Entrapment of molecular iodine produced in nuclear industry, with the Hofmann’s clathrates of formula M(L)Ni(CN)

4

where M = Fe, Ni and L an organic linear compound

Giovanni Massasso a , Yannick Guari a , Joulia Larionova a , Jerome Long a ,

Agnes Grandjean b

, Onida Barbara c

a

Université de Montpellier 2, Equipe CMOS, France b

Institut de Chimie Séparative de Marcoule (ICSM), France c

Politecnico di Torino, Italy e-mail: [email protected]

Coordination polymers with formula M'(L)M''(CN)

4

(where M and M'' are transition metals and L is an organic molecule), also known as Hofmann

’s clathrates and previously investigated for spin transition properties [1-4] and hydrogen storage at low temperature [5-6] are studied as decontaminant materials for the entrapment of molecular radioactive iodine deriving from effluents and outgasses of nuclear power plants.

Clathrates with different compositions were kept in dynamic contact with solutions of I

2

in cyclohexane, untill equilibrium conditions were reached. The final concentration was analysed at UV-VIS spectroscopy, whereas the filtered powder was detected at UV-VIS, FT-IR and Raman spectroscopy,

TGA, XRD and elemental analysis in order to quantifiy the entrapped iodine and to understand the mechanism of capture.

The capture of iodine expressed as moles of I

2

per moles of clathrate resulted to be 0.52 for Ni* and

0.48 for Fe*, for a concentration 4.1

∙10

-3

M. Change in ligand was also evaluated: a better performance of capture (about 20% improvement) was obtained by substituting pyrazine with azopyridine in Ni*.

1. R. Ohtani et al., Precise Control and Consecutive Modulation of Spin Transition Temperature Using Chemical

Migration in Porous Coordination Polymers, |J. Am. Chem. Soc. 2011, 133, 8600

–8605

2. G. Agusti et al. , Oxidative Addition of Halogens on Open Metal Sites in a Microporous Spin-Crossover Coordination

Polymer, Angew. Chem. 2009, 121, 9106

–9109

3.

G. Agustì et al. , Thermal and Light-Induced Spin Crossover Phenomena in New 3D Hofmann-Like Microporous

Metalorganic Frameworks Produced As Bulk Materials and Nanopatterned Thin Films, Chem. Mater., Vol. 20, No. 21, 2008

4. C. Bartual-Murgui et al. , Synergetic Effect of Host

–Guest Chemistry and Spin Crossover in 3D Hofmann-like Metal–

Organic Frameworks [FeHCUUNG(NERTGNNTAbpac)M(CN)4](M=Pt,Pd,Ni)**, Chem.

Eur. J.

2012, 18, 507

– 516

5. Y. Li et al. Hydrogen Storage Properties of [M(Py)Ni(CN)

4

] (M=Fe,Co,Ni), Internation Journal of Hydrogen Energy 32

(2007) 3411-3451

6. J. Rodriguez-

Hernàndez et al. , Low Temperature Structural Transformation in T[Ni(CN)

4

]xpyz with x = 1,2 ;

T=Mn,Co,Ni,Zn,Cd ; pyz=pyrazine, J. of Solid State Chemistry 183 (2010) 105-113

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