Metal ion binding by humic acid: application of the NICA-Donnan model

Article Abstract:

A model for ion binding to humic substances was developed through the combination of the non-ideal competitive adsorption (NICA) model for specific binding of electrolyte ions with a Donnan-type model for nonspecific binding. The resulting NICA-Donnan model was applied to data for H, Ca, Cd, Cu and Pb binding by a purified peat humic acid. Predictions of the competitive effect of Ca on Cd and Cu binding at various pHs were consistent with experimental data, except for some small differences. The increase in Cd and Cu binding on changing from a 0.1 M KNO3 background electrolyte to 0.01 M KNO3 was also predicted well by the NICA-Donnan model.

Models, Analysis, Humic acid, Humic acids, Cooperative binding (Biochemistry), Metal ions

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Competitive binding of protons, calcium, cadmium, and zinc to isolated cell walls of a gram-positive soil bacterium

Article Abstract:

The toxicity of pollutants in soil is determined by metal ion binding to soil or metal ion binding to the biological surfaces of organisms. Experiments using Rhodococcus erythropolis A177 show that metal toxicity is influenced by pH and the composition of the soil system. The presence of calcium, cadmium and zinc promotes competition for binding sites on the cell wall. Proton titrations suggest that metal ion binding to the cell wall is also influenced by the nature of the cell wall material.

Environmental aspects, Metals, Metals (Materials), Ligand binding (Biochemistry)

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Dissolution behavior of iron cyanide (Prussian blue) in contaminated soils

Article Abstract:

Researchers at Wageningen Agricultural University in the Netherlands performed experiments to estimate the composition and solubility of iron cyanide, or Prussian blue. Their object was to determine iron cyanide's dissolution rate in soil and potential health consequences. Prussian blue is an extremely toxic, biodegradation-resistant soil contaminant commonly found at industrial sites. Experimental procedures and results are described in detail.

Testing laboratories, Soil pollution, Industrial wastes

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