Fe(III) uptake by calcium silicate hydrates
OPEN ACCESS
Loading...
Author / Producer
Date
2020-02
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Wet chemistry and spectroscopic investigations were conducted to study Fe(III) uptake by calcium silicate hydrate (C–S–H) at different Ca/Si ratios. Wet chemistry experiments were carried out by using a 55Fe radiotracer while 29Si NMR and XAS spectroscopy were performed on C–S–H phases loaded with different Fe(III) concentrations. Sorption kinetics experiments indicate that equilibrium was attained within 30 days. Over the studied concentration range, Fe(III) sorption was linear, irrespective of the difference in pH of the suspension and the Ca/ Si of C–S–H. In addition, Fe(III) sorption on C–S–H phases was significantly stronger than Al(III) sorption. The total Fe(III) uptake by C–S–H phases, however, was limited by the lower solubility of Fe(OH)3 compared to Al (OH)3; up to 1 mol Fe/kg C–S–H (molar Fe(III)/Si ~ 0.001) could be taken up. 29Si NMR and EXAFS data suggest Fe(III) uptake in octahedral coordination into the interlayer of the C–S–H phases with Ca/Si ratios 1.2 and 1.5. However, such an uptake mechanism appears unlikely in the case of the C–S–H phase with Ca/Si 0.8 because structural parameters of Fe(III) deduced from EXAFS are different.
Permanent link
Publication status
published
Editor
Book title
Journal / series
Volume
113
Pages / Article No.
104460
Publisher
Elsevier
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
ferric iron; X-ray absorption spectroscopy; Calcium silicate hydrates; Sorption behaviour
Organisational unit
03328 - Wehrli, Bernhard (emeritus) / Wehrli, Bernhard (emeritus)