Iodine local environment in high pressure borosilicate glasses: An X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigation

The 129I radioactive isotope is a by-product of nuclear plants activity. Owing to its strong volatility, there currently no ideal protocol immobilize in waste borosilicate glasses. Recently, we have proposed the use high-pressure syntheses dissolve iodine various glass compositions; however, I speciation and dissolution mechanism could not be determined. We adopted an approach combining X-ray Photoelectron Spectroscopy (XPS) Absorption (XAS) methods determine molecular environment glasses containing from 0.5 2.5 mol.% I. XPS spectra reveal that mostly dissolved as iodide (>85% I?) with small proportion elemental (<15% I0) absence iodate species (I5+). For glasses, XAS results subsequent spectrum simulations suggested Na Ca are involved I? vicinity averaged derived coordination number (CN) 3.6 2.0 bond length nearest neighbour (rX-I) 2.98 2.85 Å, respectively. These suggest coexistence both I5+ requested for electric neutrality but instead, explain by possible interplay oxygen matrix. In addition, imply network affected dissolution.