The Role of Organic Matter in Mercury Cycle

Varshal, G. M.; Buachidze, N. S.; Velyukhanova, T. K.; Chkhetia, D. N.

doi:10.1007/978-94-009-1780-4_20

Cited by 12 publications

(16 citation statements)

References 11 publications

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“…This assumption is surely more realistic than, for instance, a ligand-exchange mechanism that leads to the coordination of Au(III) onto ionized -COO -groups (Arbozov et al 2006;Varshal et al 1995), since in acidic media (e.g. HCl solution at pH < 4) -COO -groups are few in number compared to -COOH groups (Santosa et al 2006b,c;Aleixo et al 1992;Masini 1993) Gardea-Torresdey et al 2002a).…”

Section: Removal Of Auclmentioning

confidence: 99%

Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin

Santosa

Sudiono

Siswanta

et al. 2011

Adsorption Science & Technology

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Peat soil humin, obtained after the removal of fulvic and humic acid fractions according to the recommended procedure of the International Humic Substances Society (IHSS), has the ability to remove AuCl-4 ions from aqueous solution. The removal was greatest at medium acidity, which was equivalent to pH 2.0, and it was governed by two different processes, i.e. attachment onto un-ionized-COOH groups through hydrogen bonding and reduction to Au metal by the action of the-OH group. Purification of humin through repeated immersion and shaking in a mixed solution consisting of 0.1 M HCl and 0.05 M HF led to the abrupt increase in the-COOH contents from 386 mmol/kg to 2510 mmol/kg, while the content of total-OH functional groups remained relatively constant at values slightly higher than 3000 mmol/kg. The increase in-COOH content improved the removal of AuCl-4 ions from 23 mg/g to 27 mg/g, but it was unfortunately accompanied by a diminished reduction ability to Au metal. Hence, the role of the-COOH functional group in removing AuCl-4 ions through hydrogen bonding was more significant for the purified humin, while that of the-OH group in removing AuCl-4 ions through reduction to Au metal was better for the crude (unpurified) humin.

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Section: Removal Of Auclmentioning

confidence: 99%

Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin

Santosa

Sudiono

Siswanta

et al. 2011

Adsorption Science & Technology

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“…Humic substances (HSs) are among the most abundant natural colloids that play a number of important roles in the biosphere, including soil struc turing [1,2], accumulation of nutrient microelements in a plant available form [3], and regulation of geochemical flows of metals in water and soil ecosys tems [4,5]. Therefore, in the mid 20th century, seri ous attention was paid to studying the colloidal state of humic substances, primarily in terms of soil science.…”

Section: Introductionmentioning

confidence: 99%

“…By the end of the 20th century, due to the aggrava tion of the problems of chemical pollution of the envi ronment, researchers paid attention to another prop erty of humic acids (HAs)-namely, their ability to strongly bind both metal ions and organic toxic com pounds of different natures, thus changing their migration ability [11] and reducing their bioavailabil ity and toxicity [12][13][14][15]. The capability of hydropho bic binding (solubilization) of organic compounds appears even at rather low (~1 mg/dm 3 ) HA concen trations.…”

Section: Introductionmentioning

confidence: 99%

Association and colloid-chemical properties of humic acids in aqueous solutions

et al. 2013

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Colloid chemical properties of humic acids in aqueous solutions have been studied as functions of their concentration, medium pH, and counterion nature. It has been established that, at pH < 4, Na form humic acids exist in aqueous solutions as 30-120 nm aggregates. At pH > 4, the state of humic acids depends on the solution concentration. At low concentrations, they exist as individual molecules; as the concentration is increased, they associate to form supramolecular structures at 5 mg/dm 3 and micelles at 8 g/dm 3 . An increase in the counterion charge has been shown to decrease the critical concentration of supramolecular structuring. Supramolecular structures have increased adsorbability on clay minerals and promote the mani festation of solubilizing properties of humic acids in solutions even at a concentration of 5 mg/dm 3 , which is three orders of magnitude lower than the critical micelle concentration (8 g/dm 3 ).

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“…The following two types can be recognized among the main functional groups of HAs: carboxyl COOH and phenolic OH; their main regions of dissociation are characterized by pK 3-5 and 8-9, respectively. At pH < 6, the strongly acidic carboxyl functional groups and medium strength carboxyl groups are completely dissociated [19]. In the above range of pH, humic acid is a solid phase, whereas colored solutions were observed at higher pH values; this fact is indicative of the partial or complete dissolution of HAs.…”

Section: Resultsmentioning

confidence: 96%

Interactions of peat and its components with gold and palladium ions in aqueous solutions

et al. 2015

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The processes of gold and palladium concentration by lowland peat and humic acids and nonhy drolyzed residue separated from it in a pH range characteristic of surface water were experimentally studied at the stage of peat formation. It was established that the interaction of peat with the complex chloride anions of noble metals occurs by reducing sorption. A higher affinity of the test sorbents for the complex anions of gold, as compared with that of palladium, was revealed. The experimental data suggest that gold and palla dium can be quantitatively precipitated on naturally occurring geochemical barriers.

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The Role of Organic Matter in Mercury Cycle

Cited by 12 publications

References 11 publications

Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin

Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin

Association and colloid-chemical properties of humic acids in aqueous solutions

Interactions of peat and its components with gold and palladium ions in aqueous solutions

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The Role of Organic Matter in Mercury Cycle

Cited by 12 publications

References 11 publications

Mechanism of the Removal of AuCl−4 Ions from Aqueous Solution by Means of Peat Soil Humin

Mechanism of the Removal of AuCl−4 Ions from Aqueous Solution by Means of Peat Soil Humin

Association and colloid-chemical properties of humic acids in aqueous solutions

Interactions of peat and its components with gold and palladium ions in aqueous solutions

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Product

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Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin

Mechanism of the Removal of AuCl⁻₄ Ions from Aqueous Solution by Means of Peat Soil Humin