Chromate and oxalate adsorption on geothite. 2. Surface complexation modeling of competitive adsorption

Journal Article · Mon Nov 30 23:00:00 EST 1992 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00036a005· OSTI ID:7234420

Mesuere, K; Fish, W ^[1]

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1. Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States)

Adsorption of binary mixtures of chromate and oxalate onto [alpha]-FeOOH was quantified as a function of pH for a wide range of absorbate concentrations. Oxalate diminished the adsorption of chromate most effectively at low pH and when adsorbate concentrations were near surface-saturation levels. Chromate significantly inhibited oxalate adsorption over the entire pH range, reflecting the higher affinity of chromate for the [alpha]-FeOOH surface. The results indicate the adsorption of organic acids can enhance the mobility of chromate in acidic environments, while competitive adsorption of inorganic oxy anions may sharply diminish organic acid adsorption, thereby exerting an important control on mineral weathering rates. The ability of two surface complexation models to quantitatively predict the binary-solute data was evaluated using model constants that successfully described goethite surface hydrolysis and single-solute adsorption. Diffuse layer and triple-layer model simulations were highly similar and quantitatively accounted for binary-solute adsorption as a function of pH when surface concentrations of both coadsorbates were high. However, these models significantly underpredicted adsorption of minor species. 58 refs., 7 figs.

• DOE Contract Number: FG06-89ER60845
• OSTI ID: 7234420
• Journal Information: Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 26:12; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ADSORPTION
AFFINITY
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMATES
CHROMIUM COMPOUNDS
COMPLEXES
DECOMPOSITION
GOETHITE
HYDROLYSIS
IRON COMPOUNDS
IRON OXIDES
LAND POLLUTION
LYSIS
MATHEMATICAL MODELS
MINERALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXALATES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POLLUTION
SOLVOLYSIS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
WEATHERING