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Caesium incorporation and retention in illite interlayers

DOI: 10.1016/j.clay.2015.02.008 DOI Help

Authors: Adam J. Fuller (University of Leeds) , Sam Shaw (University of Manchester) , Michael B. Ward (University of Manchester) , Sarah Haigh (University of Manchester) , Fred Mosselmans (Diamond Light Source) , Caroline Peacock (University of Leeds) , Stephen Stackhouse (University of Leeds) , Andrew Dent (Diamond Light Source Ltd) , Divyesh Trivedi (National Nuclear Laboratory Ltd UK) , Ian T. Burke (University of Leeds)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Applied Clay Science

State: Published (Approved)
Published: February 2015
Diamond Proposal Number(s): 4901

Open Access Open Access

Abstract: Radioactive caesium (chiefly 137Cs) is a major environmental pollutant. The mobility of Cs in temperate soils is primarily controlled by sorption onto clay minerals, particularly the frayed edges of illite interlayers. This paper investigates the adsorption of Cs to illite at the molecular scale, over both the short and long term. Transmission electron microscopy (TEM) images showed that after initial absorption into the frayed edges, Cs migrated into the illite interlayer becoming incorporated within the mineral structure. Caesium initially exchanged with hydrated Ca at the frayed edges, causing them to collapse. This process was irreversible as Cs held in the collapsed interlayers was not exchangeable with Ca. Over the long term Cs did not remain at the edge of the illite crystals, but diffused into the interlayers by exchange with K. Results from extended X-ray absorption fine structure spectroscopy (EXAFS) and density functional theory modelling confirmed that Cs was incorporated into the illite interlayer and revealed its bonding environment.

Journal Keywords: Cs; Tem; Illite; Dft; Exafs

Subject Areas: Environment, Earth Science, Materials

Instruments: B18-Core EXAFS