title: Characterization of silver-kaolinite (AgK): an adsorbent for long-lived (129)I species.
abstract: Bentonite is a preferred buffer and backfill material for deep geological disposal of high-level nuclear waste (HLW). Bentonite does not retain anions by virtue of its negatively charged basal surface. Imparting anion retention ability to bentonite is important to enable the expansive clay to retain long-lived (129)I (iodine-129; half-life = 16 million years) species that may escape from the HLW geological repository. Silver-kaolinite (AgK) material is prepared as an additive to improve the iodide retention capacity of bentonite. The AgK is prepared by heating kaolinite-silver nitrate mix at 400 °C to study the kaolinite influence on the transition metal ion when reacting at its dehydroxylation temperature. Thermo gravimetric-Evolved Gas Detection analysis, X-ray diffraction analysis, X-ray photo electron spectroscopy and electron probe micro analysis indicated that silver occurs as AgO/Ag2O surface coating on thermally reacting kaolinite with silver nitrate at 400 °C.
authors.affiliation: Geoenvironmental Research Centre, Cardiff University, Cardiff, CF24 3AA UK.
authors.forename: Sivachidambaram
authors.initials: S
authors.lastname: Sadasivam
authors.affiliation: Department of Civil Engineering and Centre for Sustainable Technologies, Indian Institute of Science, Bangalore, 560012 India.
authors.forename: Sudhakar M
authors.initials: SM
authors.lastname: Rao
keywords: Kaolinte; Radioactive waste; Silver; Thermal reaction; XPS