Charge adjustments upon adsorption of a weak polyelectrolyte to a mineral oxide: The hematite-humic acid system

Journal Article · Thu Apr 01 04:00:00 EST 1999 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1998.6050· OSTI ID:338574

Vermeer, A W.P.; Koopal, L K ^[1]

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1. Wageningen Agricultural Univ. (Netherlands). Lab. of Physical Chemistry and Colloid Science

The proton adsorption to a mixture of purified Aldrich humic acid (PAHA) and hematite is investigated. Basic insight into the charge adjustment process is obtained by using a self-consistent-field lattice theory for polyelectrolyte adsorption. The calculations indicate that upon adsorption the component with the highest initial charge density tends to induce charges on the other component. The number of induced charges can show a maximum when the surface charge and the charge of the segments in direct contact with the surface roughly balance each other. Experimentally, the humic acid-hematite system is investigated by proton titrations. The alterations in charge density caused by adsorption of PAHA to hematite are investigated by comparing the proton adsorption on the individual samples with that on their mixtures. Upon adsorption a part of the functional groups of humic acid forms complexes with some of the surface sites of hematite. This interaction reduces the proton binding to the humic acid at relatively low pH and it promotes the proton adsorption on the oxide surface at relatively high pH.

• OSTI ID: 338574
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 1 Vol. 212; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
HEMATITE
HUMIC ACIDS
REMEDIAL ACTION
SOILS
SORPTIVE PROPERTIES
SURFACE POTENTIAL