Thermodynamic modeling of solid solutions between monosulfate and monochromate 3CaO Bullet Al{sub 2}O{sub 3} Bullet Ca[(CrO{sub 4}){sub x}(SO{sub 4}){sub 1-x}] Bullet nH{sub 2}O

Journal Article · Sun Jan 15 00:00:00 EST 2012 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2011.09.005· OSTI ID:21596951

Lothenbach, Barbara; Le Saout, Gwenn ^[1]; Johnson, C Annette ^[2]

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1. Empa, Swiss Federal Laboratories for Concrete and Construction Chemistry, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)
2. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Duebendorf (Switzerland)

In hydrated cement paste AFm-phases are regarded to play an important role in the binding of the toxic contaminant chromate through isomorphic substitution with sulfate. Solid solutions formation can lower the solubility of the solids, thus reducing chromate leaching concentrations. Solid solutions between monosulfate and monochromate were synthesized and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and inductive coupled plasma optical emission spectroscopy (ICP-OES). Based on the measured ion concentrations in solution total solubility products of the solid solution series were determined. For pure monochromate a logK = - 28.4 {+-} 0.7 was determined. Results from solid and solution analysis showed that limited solid solutions exist. Based on XRD diffractograms a solid solution with a miscibility gap 0.15 < Crx < 0.85 with a dimensionless Guggenheim parameter of 2.43 was proposed.

• OSTI ID: 21596951
• Journal Information: Cement and Concrete Research, Vol. 42, Issue 1; Other Information: DOI: 10.1016/j.cemconres.2011.09.005; PII: S0008-8846(11)00236-5; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0008-8846
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CEMENTS
CHROMATES
EMISSION SPECTROSCOPY
LEACHING
SCANNING ELECTRON MICROSCOPY
SIMULATION
SOLID SOLUTIONS
SOLUBILITY
SULFATES
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ALUMINIUM COMPOUNDS
BUILDING MATERIALS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHROMIUM COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
DISPERSIONS
DISSOLUTION
ELECTRON MICROSCOPY
GRAVIMETRIC ANALYSIS
HOMOGENEOUS MIXTURES
MATERIALS
MICROSCOPY
MIXTURES
OXIDES
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
SCATTERING
SEPARATION PROCESSES
SOLUTIONS
SPECTROSCOPY
SULFUR COMPOUNDS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS