Immobilization of chromium (VI) evaluated by binding isotherms for ground granulated blast furnace slag and ordinary Portland cement

Laforest, Guylaine; Duchesne, Josée

doi:10.1016/j.cemconres.2004.12.011

Cited by 56 publications

(26 citation statements)

References 19 publications

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“…In this case, the CrO 4 2-anions can be incorporated into the interlayer space of the hydrocalumite-like compound, giving rise to a signal in the XRD pattern, in good agreement with several previous works [43][44][45].…”

Section: Chromium(vi) Saltssupporting

confidence: 76%

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Durán

Sirera

Perez-Nicolas

et al. 2016

Cement and Concrete Research

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The effect of chlorides and nitrates of Li(I), Cr(III), Zn(II), Cu(II), Pb(II) nitrate and Cr(VI) (chromate) on the early hydration of ternary system of calcium aluminates (CA, CA 2 , C 12 A 7 ) was reported. Li(I) and Cr(III) caused a strong acceleration of the hydration, while Zn(II) as well as chromate gave rise to a slight acceleration. On the contrary, Pb(II) and Cu(II) retarded the hydration. A clear formation of AFm phases during the first hydration stages was found and related to the acceleration ability.Anions (nitrate or chloride as counterions or even chromate) were able to be incorporated into the interlayer space of AFm, yielding insoluble and stable compounds.A balance between the insolubility of the metal hydroxides (dependant on the low amphoteric character of the compound) and the ability of the formation of AFm hydrates seems to be very important to lean the equilibrium towards the retarding of the hydration or towards the acceleration, respectively.2

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Section: Chromium(vi) Saltssupporting

confidence: 76%

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Durán

Sirera

Perez-Nicolas

et al. 2016

Cement and Concrete Research

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“…Possible minerals might be barium chromate (BaCrO 4 ) or a solid solution with sulfate (Ba(S,Cr)O 4 ) [24]. At very high chromium contents precipitation of CaCrO 4 was observed [20,25].…”

Section: Chromium Molybdenum and Vanadiummentioning

confidence: 99%

Binding and leaching of trace elements in Portland cement pastes

Vollpracht

Brameshuber

2016

Cement and Concrete Research

100

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“…This high reductive capacity of Portland cement determined by the Cr(VI) method could result from the coprecipitation of Cr(VI) with CaCO 3 formed at alkaline pH during the 7-day reaction with Portland cement powder (Hua et al 2007;Tang et al 2007), not from the reduction of Cr(VI) to Cr(III) only. A previous study also reported that Cr-bearing phases such as CaCrO 4 and CaCrO 4 •2H 2 O were formed at alkaline pH (10.5-12.2) during the reaction of Portland cement with high-Cr-concentration solution (15,000-50,000 mg/L) (Laforest and Duchesne 2005), suggesting that the high reductive capacity of Portland cement determined by the Cr(VI) method could be overestimated by the precipitation of Cr-bearing phases. A previously reported reductive capacity of Portland cement measured by the Cr(VI) method was 0.035 meq/g which is lower than the 0.349 meq/g in this study.…”

Section: Reductive Capacity Of Dry Ingredientsmentioning

confidence: 99%

Characterization of Technetium Speciation in Cast Stone

Um¹,

Jung²,

Wang³

et al. 2013

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Executive SummaryThis report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, "Production and Long-Term Performance of Low Temperature Waste Forms" to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability from Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.Various formulations of Cast Stone that include secondary waste simulants and different LAW simulants have been characterized previously. For this report, smaller Cast Stone monoliths were prepared with high Tc concentrations spiked into the 7.8 M Na overall average LAW simulant using dry ingredients from two different sources (referred to as NW and SE). These small Cast Stone monoliths were used for this Tc speciation characterization. The following subtasks are included within the Tc speciation characterization task:1. Measure the reductive capacity of different types of dry ingredients, the 8 LAW simulants used in Westsik et al. (2013), and short-term cured Cast Stone before and after leaching with different leaching conditions. The reductive capacities of dry ingredients from NW and SE sources, various LAW simulants, and final Cast Stone before and after leaching tests were measured using two different methods, the Ce(IV) and Cr(VI) methods. One type of blast furnace slag (BFS) and the high-Ca fly ash were obtained from LaFarge North America Inc. in Pasco, Washington, and these materials are referred to as the NW slag and fly ash. The second BFS and the low-Ca fly ash are the same materials used in the Saltstone processing facility at the Savannah River Site in South Carolina and are referred to as the SE materials. Much more of the solids dissolve in the strong acid (pH ~1-2) environment created by the Ce(IV) method compared to circumneutral pH (~7.0) condition created by the Cr(VII) method. Among the dry ingredients, the reductive capacity measured by the Ce(IV) method was the highest for BFS (0.793 meq/g for NW slag and 0.800 meq/g for SE slag). The reductive ...

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Immobilization of chromium (VI) evaluated by binding isotherms for ground granulated blast furnace slag and ordinary Portland cement

Cited by 56 publications

References 19 publications

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Binding and leaching of trace elements in Portland cement pastes

Characterization of Technetium Speciation in Cast Stone

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