Acid/base reactions and Al(III) complexation at the surface of goethite

Journal Article · Tue May 01 04:00:00 EDT 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90154-D· OSTI ID:6142286

Loevgren, L; Sjoeberg, S ^[1]; Schindler, P W ^[2]

---

1. Univ. of Umea (Sweden)
2. Univ. of Bern (Switzerland)

Acid/base reactions and Al(III) complexation at the geothite-solution interface have been investigated at 298.2 K in NaNO{sub 3} solutions at a constant ionic strength of 0.1 M. Equilibrium measurements were performed as potentiometric titrations using a glass electrode. The experimental data were evaluated on the basis of the constant capacitance model. The acid/base properties are described by the equilibria and the intrinsic equilibrium constants: {triple bond}FeOH + H{sup +} {r reversible} {triple bond}FeOH{sup +}{sub 2}; log {beta}{sup s}{sub 1,1,0(int)} = 7.47 {plus minus}0.02, and {triple bond}FeOH {r reversible} {triple bond}FeO{sup {minus}} + H{sup +}; log {beta}{sup s}{sub {minus}1,1,0(int)} = {minus}9.51 {plus minus} 0.04. The specific capacitance was determined to be 1.28 F m{sup {minus}2}. Aluminium(III) complexation within the range 3.0 < {minus}log(H{sup +}) < 8.5 results in the formation of the monodentate species {triple bond}Fe-O-Al-OH{sup +} (log {beta}{sup s}{sub {minus}2,1,1(int)} = {minus}1.49 {plus minus}0.04) and {triple bond}Fe-O-Al-(OH){sup 0}{sub 2} (log {beta}{sup s}{sub {minus}3,1,1(int)} = {minus}9.10 {plus minus} 0.08). Whereas the acid base reactions were fully reversible, the aluminium desorption was found to be extremely slow and showed poor reversibility.

• OSTI ID: 6142286
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:5; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ACIDIFICATION
ALKALI METAL COMPOUNDS
ALUMINIUM COMPLEXES
ALUMINIUM IONS
BASES
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMISTRY
COMPLEXES
DESORPTION
EQUILIBRIUM
GEOCHEMISTRY
GOETHITE
GROUND WATER
HYDROGEN COMPOUNDS
IONIC COMPOSITION
IONS
KINETICS
MINERALS
NITRATES
NITROGEN COMPOUNDS
OXIDE MINERALS
OXYGEN COMPOUNDS
PH VALUE
REACTION KINETICS
ROCK-FLUID INTERACTIONS
SODIUM COMPOUNDS
SODIUM NITRATES
SOLUBILITY
STRUCTURAL CHEMICAL ANALYSIS
TITRATION
WATER