Complexation of Pb(II) at the goethite ([alpha]-FeOOH)/water interface: The influence of chloride

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90225-9· OSTI ID:6611436

Gunneriusson, L; Loevgren, L; Sjoeberg, S ^[1]

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1. Univ. of Umea (Sweden)

The complexation of Pb(II) on a hydrous goethite surface has been investigated. Equilibrium measurements have been performed as potentiometric titrations at 298.2 K, within the range 2.7 < -log [H[sup +]] < 8.5. Three different ionic media were used: 0.1 mol dm[sup [minus]3] NaNO[sub 3], 0.1 mol dm[sup [minus]3] NaCl, and a mixture (1:1) of both these media. The evaluation of experimental data was made, using the constant capacitance model, within which a previously determined model for the acid-base reactions was included. The formation of the following complexes within the system H[sup +] - [triple bond]FeOH - Pb[sup 2+], was found to describe the surface complexation: [triple bond]FeOHPb[sup 2+] (log [beta][sub 0,1,1,0][sup s](int) = 8.20 [+-] 0.06); [triple bond]FeOPb[sup +] (log [beta][sub -1,1,1,0][sup s](int) = 0.17 [+-] 0.04); [triple bond]FeOPbOH (log [beta][sub -2,1,1,0][sup s](int) = -8.85 [+-] 0.08). Within the four component system H[sup +] - [triple bond]FeOH - Pb[sup 2+] - Cl[sup [minus]], the following complexes were added to the model: [triple bond]FeOHPbCl[sup +] (log [beta][sub 0,1,1,1][sup s](int) = 7.50 [+-] 0.08); [triple bond]FeOPbCl (log [beta][sub -1,1,1,1][sup 2](int) = -0.35 [+-] 0.16); [triple bond]FeOPbOHCl[sup [minus]] (log [beta][sub -2,1,1,1][sup s](int) = -8.00 [+-] 0.12). In the presence of an excess of Pb(II) ions to surface binding sites, the formation of a polynuclear surface Pb(II) species is postulated. The proposed model has been verified by independent determination of total soluble Pb(II) concentrations. Model calculations, using concentrations typical for natural waters, demonstrate a strong adsorption of Pb(II) even at low concentrations of surface binding sites. The experimental data show fully reversible reactions.

• OSTI ID: 6611436
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 58:22; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202 -- Isotope Effects
Isotope Exchange
&amp; Isotope Separation
54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring &amp; Transport-- (1990-)
ADSORPTION
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHLORIDES
CHLORINE COMPOUNDS
ENVIRONMENTAL TRANSPORT
GOETHITE
GROUND WATER
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
IONS
KINETICS
LEAD IONS
MASS TRANSFER
MATHEMATICAL MODELS
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
REACTION KINETICS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
WATER