Application of mass transport theory to the leaching of radionuclides from waste solids

Portland cement‐based materials are frequently used for fixing heavy metals but are not very effective for arsenic. Alternatively, alkali activated metakaolin and fly ash systems were tested for arsenic retention by the toxic characteristic leaching procedure and American Nuclear Society 16.1 methods. The influence of Fe and Mn on As leaching rates was assessed. These materials perform well in aggressive environments (pH<3) but the activated metakaolin matrix is less able to retain As than the activated fly ash matrix. The leaching in fly ash matrices occurs in two steps: immediate initial leaching followed by a slow diffusion‐controlled process.

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“…(C) Leaching Behavior of As Leaching of As was characterized by applying the equations of Godbee et al 24 . adapted by Conner 4 .…”

Section: Resultsmentioning

confidence: 99%

Fixing Arsenic in Alkali‐Activated Cementitious Matrices

Fernández-Jiménez

Palomo

Macphee

et al. 2005

Journal of the American Ceramic Society

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“…It is often found that actual leach data indicate a much faster release in the early time periods of the leach test and later satisfy the linear dependence of square root of the time parameter. Matsuzuru and Moriyama (1982), Godbee et al (1980), Matsuzuru and Ito (1978), and Dayal et al(1983) discuss cement waste form leach experiments that show a simiiar initial rapid release.…”

Section: Cm2/s For Comparison Mostmentioning

confidence: 99%

Geochemical factors affecting radionuclide transport through near and far fields at a Low-Level Waste Disposal Site

Kaplan¹,

Seme

Piepkho

1995

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“…Hence, dissolution reactions can be treated as diffusion-controlled fast reactions. The whole process than can be described as steady state diffusion across the leachate layer, and unsteady state diffusioncontrolled fast reactions in the porous leaching front [28].…”

Section: Leaching Mechanismmentioning

confidence: 99%