The sorption of humic acids to mineral surfaces and their roles in contaminant binding
Humic substances dissolved in groundwater may adsorb to certain mineral surfaces, rendering hydrophilic surfaces hydrophobic and making them sorbents for hydrophobic organic compounds (HOC). The sorption of humic and fulvic acids (International Humic Substance Society, IHSS, reference samples) on hematite and kaolinite was investigated to determine how natural organic coatings influence HOC sorption. The sorption behavior of the humic substances was consistent with a ligand-exchange mechanism, and the amount of sorption depended on the concentration of hydroxylated surface sites on the mineral and the properties of the humic substance. The sorption of the humic substances to two solids was proportional to their aromatic carbon content and inversely proportional to the O/C ratio. Increasing quantities of sorbed humic substances (f{sub oc}0.01 to 0. 5%) increased the sorption of carbazole, dibenzothiophene, and anthracene. Peat humic acid, the most aromatic coating, showed the greatest sorption enhancement of HOC when sorbed to hematite. In addition, HOC sorption was greater on organic coating formed at low ionic strength (I = 0.005) as compared to higher ionic strength (I = 0.1). We suggest that both the mineral surface and the ionic strength of the electrolyte affect the interfacial configuration of the sorbed humic substance, altering the size or accessibly of hydrophobic domains on the humic molecule to HOC. 30 refs., 5 figs.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6280294
- Report Number(s):
- PNL-SA-18877; CONF-9008177-1; ON: DE91005678
- Resource Relation:
- Conference: 5. International Humid Substance Society meeting, Nagoya (Japan), 6-10 Aug 1990
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
36 MATERIALS SCIENCE
ANTHRACENE
SORPTION
CARBAZOLES
HEMATITE
SORPTIVE PROPERTIES
HUMIC ACIDS
KAOLINITE
LIGANDS
ION EXCHANGE
POLYCYCLIC SULFUR HETEROCYCLES
ADSORPTION ISOTHERMS
ENVIRONMENTAL TRANSPORT
FULVIC ACIDS
IONIC COMPOSITION
PH VALUE
SURFACES
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
AROMATICS
AZAARENES
AZOLES
CHALCOGENIDES
CONDENSED AROMATICS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
IRON COMPOUNDS
IRON ORES
IRON OXIDES
ISOTHERMS
MASS TRANSFER
MINERALS
ORES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
540210* - Environment
Terrestrial- Basic Studies- (1990-)
580000 - Geosciences
360603 - Materials- Properties