Complexation at low concentrations of methyl and inorganic mercury(II) to a hydrous goethite ([alpha]-FeOOH) surface

Journal Article · Wed Feb 01 04:00:00 EST 1995 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1995.1033· OSTI ID:6621622

Gunneriusson, L; Baxter, D; Emteborg, H ^[1]

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1. Univ. of Umeaa (Sweden)

Surface complexation of inorganic mercury(II) and monomethyl (CH[sub 3]Hg[sup +]) onto a hydrous goethite ([alpha]-FeOOH) surface has been studied. The pH ([minus]log[H[sup +]]) has been varied within the range 2.7 < [minus]log[H[sup +]] < 9, at 298 K, using a 0.1 mol dm[sup 3] NaNO[sub 3] medium. Low total mercury concentrations ([approx] 1 mmol/dm[sup 3]) were used. Inorganic mercury and methyl mercury content in the water phase, in the goethite phase, and adsorbed on the vessel walls was determined by GFAAS and GC-coupled MIP-AES. The inorganic mercury distribution was evaluated, using a previously determined surface complexation model, based on the constant capacitance concept. This model was derived using about 10[sup 3] times higher total mercury concentrations. In the presence of goethite, approximately 80% of both methyl mercury and inorganic mercury(II) was recovered in the different phases. The extractable fraction adsorbed to the vessel walls was found to be low. About 20% of the inorganic mercury added remained soluble in the presence of goethite. This is close to the predicted value, using a previously determined model derived in the mmol/dm[sup 3] range. This implies that the concept of specific high affinity sites is questionable in the case of near trace concentrations of Hg(II). Methyl mercury was found to be weakly coordinated, with about 15% adsorbed on the goethite surface. Furthermore, a model calculation describing the surface complexation of methyl mercury on goethite was performed. The experimental data could best be explained by the formation of the surface complexes [triple bond]FeOHHgCH[sub 3][sup +] and [triple bond]FeOHgCH[sub 3].

• OSTI ID: 6621622
• Journal Information: Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 169:2; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring &amp; Transport-- (1990-)
CHEMICAL REACTIONS
CHEMISORPTION
CHEMISTRY
COMPLEXES
ENVIRONMENTAL TRANSPORT
GOETHITE
MASS TRANSFER
MATHEMATICAL MODELS
MERCURY COMPOUNDS
METHYLMERCURY
MINERALS
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
OXIDE MINERALS
PH VALUE
SEPARATION PROCESSES
SOIL CHEMISTRY
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES