Immobilization of chromium in cement matrices

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Waste Management; (United States)

DOI:https://doi.org/10.1016/0956-053X(94)90016-7· OSTI ID:7239778

Kindness, A; Macias, A; Glasser, F P ^[1]

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1. Univ. of Aberdeen, Old Aberdeen (United Kingdom). Dept. of Chemistry

Portland cement and blended cements containing blast furnace slag afford both physical and chemical immobilization of chromium. To separate physical and chemical effects, the pore fluid contained in set, hydrated cements has been expressed and analyzed. In Portland cement spiked with 5,000 ppm Cr(III), pore fluid levels are 0.1--1 ppm, whereas in well-cured slag blends, they decrease to <0.01 ppm. Both cement types give chemical immobilization, but slag cements give the better performance. Slag-containing cements are the most effective at removing Cr(VI) from the pore fluid, probably by reducing Cr(VI) to Cr(III). Electron microscopy coupled with energy dispersive X-ray analysis shows that Cr(III) can be substituted for Al in most of the calcium aluminated hydrate phases. In synthetic preparations, substitution is complete resulting in Ca-Cr phases that are isostructural to calcium aluminate phases. Three Cr analogues of calcium aluminates were synthesized: Ca[sub 2]Cr(OH)[sub 7] [center dot] 3H[sub 2]O, Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 6H[sub 2]O and Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 8H[sub 2]O, as well as solid solutions, e.g., Cr substituted hydrogarnet 3CaO [center dot] (Al[sub 2]O[sub 3]/Cr[sub 2]O[sub 3]) [center dot] 6H[sub 2]O. There is no real evidence that Cr is taken up by C-S-H gel.

• OSTI ID: 7239778
• Journal Information: Waste Management; (United States), Vol. 14:1; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CEMENTS
STABILITY
CHROMIUM
WASTE PROCESSING
AQUEOUS SOLUTIONS
MATERIALS RECOVERY
REMEDIAL ACTION
SOLIDIFICATION
STABILIZATION
BUILDING MATERIALS
DISPERSIONS
ELEMENTS
MANAGEMENT
MATERIALS
METALS
MIXTURES
PHASE TRANSFORMATIONS
PROCESSING
SOLUTIONS
TRANSITION ELEMENTS
WASTE MANAGEMENT
540220* - Environment
Terrestrial- Chemicals Monitoring &amp; Transport- (1990-)