Investigation of the maximum dissolution rates and temperature dependence of a simulated UK nuclear waste glass in circum-neutral media at 40 and 90 ° C in a dynamic system

Iwalewa, Tajudeen M. and Qu, Tingyu and Farnan, Ian (2017) Investigation of the maximum dissolution rates and temperature dependence of a simulated UK nuclear waste glass in circum-neutral media at 40 and 90 ° C in a dynamic system. Applied Geochemistry, 82. pp. 177-190. ISSN 0883-2927 DOI https://doi.org/10.1016/j.apgeochem.2017.05.018

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Official URL: https://doi.org/10.1016/j.apgeochem.2017.05.018

Abstract

This study investigates the influence of temperature on the dissolution of MW25, a non-radioactive simulant of UK Magnox glass. A single-pass flow-through (SPFT) system was used to measure the forward dissolution rate of MW25 at 40 and 90 °C and circum-neutral pH. The forward dissolution rate was found to be approximately one order of magnitude higher at 90 °C than at 40 °C. A similar release was observed for Si, Mg and Al at 40 °C and 90 °C, whereas the B, Cs, Na, Li and Mo showed an order of magnitude increase when the temperature was increased from 40 to 90 °C for low q/S values. The temperature dependence of the dissolution rates was determined using the Arrhenius rate law and the resultant activation energy (Ea) shows that the dissolution process is a surface phenomenon. At 90 °C, the net effect of the processes governing MW25 dissolution led to preferential release of boron and alkali metals relative to the release of Si during the transient dissolution stage, accompanied by an increase in the concentration of silicic acid. This suggests that the solution activity of silicic acid at higher temperature has a weak influence on the release of the mobile elements. This study features a new method for estimating the surface area of reacted glass powder more accurately than the geometric surface area estimate, which is the preferred standard method among researchers.

Item Type: Article
Uncontrolled Keywords: 2017AREP; IA76
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
12 - PhD
Journal or Publication Title: Applied Geochemistry
Volume: 82
Page Range: pp. 177-190
Identification Number: https://doi.org/10.1016/j.apgeochem.2017.05.018
Depositing User: Sarah Humbert
Date Deposited: 14 Apr 2020 17:15
Last Modified: 14 Apr 2020 17:15
URI: http://eprints.esc.cam.ac.uk/id/eprint/4685

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