Chromate and oxalate adsorption on goethite. 1. Calibration of surface complexation models

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00036a004· OSTI ID:7234411

Mesuere, K; Fish, W ^[1]

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

Adsorption of chromate and oxalate on [alpha]-FeOOH was quantified for single-adsorbate systems as a function of pH, ionic strength and adsorbate and adsorbent concentrations. The comprehensive data base was used to calibrate and compare two surface complexation models. Both anions exhibited Langmuir-type adsorption with maximum adsorption densities ([Gamma][sub max]) of 2.2 (oxalate) and 2.4 [mu]mol/m[sup 2] (chromate). Increasing ionic strength diminished the adsorption of both anions. However, the background electrolyte affected oxalate adsorption more than chromate adsorption, reflecting a higher intrinsic affinity of chromate for the goethite surface. Measured proton/anion adsorption stoichiometry ratios (r[sub H]) ranged from 0.3 to 1.1, increased with pH, but showed little dependence on surface concentration of adsorbates. The diffuse layer model (DLM) and triple-layer model (TLM) reproduced all major adsorption features with a single set of constants for each model, but more surface species were required for the DLM. Another difference between models arose in the computation of r[sub H]: DLM-calculated values were closer to the experimental values. 49 refs., 7 figs., 4 tabs.

• DOE Contract Number: FG06-89ER60845
• OSTI ID: 7234411
• 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
CALIBRATION
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHROMATES
CHROMIUM COMPOUNDS
COMPILED DATA
COMPLEXES
DATA
GOETHITE
INFORMATION
IRON COMPOUNDS
IRON OXIDES
LAND POLLUTION
MATHEMATICAL MODELS
MINERALS
NUMERICAL DATA
OXALATES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POLLUTION
SORPTION
STOICHIOMETRY
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS