Cation exchange properties of humic acids and their importance in the geochemical enrichment of UO2++ and other cations

Szalay, A.

doi:10.1016/0016-7037(64)90009-2

Cited by 201 publications

(54 citation statements)

References 2 publications

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“…Uranium is not reduced by interaction with humic acids, but rather is strongly adsorbed (Nash et al, 1981). Szalay (1964) likened humic acids to cation exchange columns, and found that Langmuir iso-pH curves described well the adsorption equilibrium of humic acids (see section on Modelling). The Langmuir equation is characterized by two constants representing a geochemical enrichment factor (GEF) and the adsorption capacity.…”

Section: Adsorptionmentioning

confidence: 85%

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The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

304

134

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We describe a three step process for the removal of uranium (U) from dilute waste waters.Step one involves the sequestration of U on, in, and around aquatic plants such as algae. Cell wall ligands efficiently remove U(VI) from waste water. Growing algae continuously renew the cellular surface area.Step 2 is the removal of U-algal particulates from the water column to the sediments.Step 3 involves reducing U(VI) to U(IV) and transforming the ions into stable precipitates in the sediments. The algal cells provide organic carbon and other nutrients to heterotrophic microbial consortia to maintain the low E H , within which the U is transformed.Among the microorganisms, algae are of predominant interest for the ecological engineer because of their ability to sequester U and because some algae can live under many extreme environments, often in abundance. Algae grow in a wide spectrum of water qualities, from alkaline environments (Chara, Nitella) to acidic mine drainage waste waters (Mougeotia, Ulothrix). If they could be induced to grow in waste waters, they would provide a simple, longterm means to remove U and other radionuclides from U mining effluents. This paper reviews the literature on algal and microbial adsorption, reduction, and transformation of U in waste streams, wetlands, lakes and oceans.

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Section: Adsorptionmentioning

confidence: 85%

“…The interaction of humic substances with U binding to algal cells was also studied by Szalay (1964). The adsorptive properties of humic acids probably relate to the carboxyl and hydroxyl groups associated with the breakdown of lignin.…”

Section: Adsorptionmentioning

confidence: 99%

The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

304

134

View full text Add to dashboard Cite

show abstract

“…At ambient temperatures (-25 OC), U is adsorbed to humic substances through rapid ion-exchange and complexation processes with carboxylic and other acidic functional groups (Idiz et al 1986 Borovec et al 1979, Szalay 1964 without reduction to the U(IV) species. It has been suggested that U(VI) adsorbed (or fixed) to organic matter may undergo reduction to U(IV) followed by precipitation of UO, (Andreyev and Chumachenko 1964).…”

Section: Sorptionmentioning

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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“…The source of UO 2 +2 is probably apatite, which is a known host for U in igneous rocks. However, uranium in sedimentary rocks is invariably associated with organic matter (Abdel-Gawad and Kerr, 1961;Szalay, 1964;Mohan et al, 1982;Drew Ilger et al, 1987) or with accessory detrital minerals such as zircon (ZrSiO 4 ). Humic acids within the organic matter sequester UO 2 +2 through complexation on carboxyl functional groups (R-COOH) (Szalay, 1964;Drew Ilger et al, 1987) Nefedov et al, 1998) leading to enrichment factors over contacting groundwaters by a factor as high as 10,000 (Szalay, 1964 + although direct microbial reduction of U(VI) to U(IV) has also been observed under anaerobic conditions (Suzuki et al, 2005).…”

Section: Mercurymentioning

confidence: 99%