Acid-base surface chemistry and sorption of some lanthanides on K{sup +}-saturated Marblehead illite: 1. Results of an experimental investigation
The surface reactivity and sorption of Nd and Eu onto K{sup +}-saturated, Marblehead illite has been investigated in 0.01, 0.1, and 1.0 M KCl solutions at 25 C; the potentiometric titrations were conducted using back-titration techniques. Batch experimental protocols were used in both series of studies. The ionic strength-dependent, proton surface charge density ({sigma}{sub H}) varies from {minus}1500 to {minus}1,700 mC/m{sup 2} in 1.0 M KCl solutions and from {minus}1800 to {minus}2,200 mC/m{sup 2} in 0.01 and 0.1 M KCl solutions. An isoelectric point was not defined by the {sigma}{sub H} vs. pH curves, which reflects the multi-phase nature of natural illitic materials. The functional dependence of REE binding constants (log K{sub e}) on surface coverage (log {Gamma}{sub REE}) indicates the existence of a multiplicity of energetically distinct surface types. These surface site types include amphoteric silanol and aluminol sites, basal planar surfaces, and frayed edges; the frayed edges are observed only in low ionic strength solutions (I {le} 0.1 M KCl).
- Research Organization:
- Ministry of Emergency and Chernobyl Management, Kiev (UA)
- OSTI ID:
- 20014544
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 64, Issue 2; Other Information: PBD: Jan 2000; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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