Rare earth element complexation by PO sub 4 sup 3 minus ions in aqueous solution

Journal Article · Tue Oct 01 00:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90439-C· OSTI ID:7114351

Byrne, R H; Lee, Jong Hyeon; Bingler, L S ^[1]

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1. Univ. of South Florida, Petersburg (United States)

Complexation of trivalent rare earths by PO{sub 4}{sup 3{minus}} ions has been assessed at t = 25C by examining the influence of aqueous phosphate concentrations on the distributions of {sup 144}Ce and {sup 153}Gd between 0.68 molar NaClO{sub 4} and tributyl phosphate (TBP). The authors estimates of these formation constants at zero ionic strength are approximately seven to eight orders of magnitude lower than previously reported estimates for lanthanide and actinide PO{sub 4}{sup 3{minus}} complexation. Linear free energy relationships relating the complexation of Ca{sup 2+} and lanthanides (Ln{sup 3+}) by a variety of organic ligands, in conjunction with previous direct observations of CaPO{sub 4}{sup {minus}} formation, are consistent with the experimentally derived CePO{sub 4}{sup 0} and GdPO{sub 4}{sup 0} formation constants reported in this work. Gadolinium speciation calculations indicate that the PO{sub 4}{sup 3{minus}} ion can effectively compete with the CO{sub 3}{sup 2{minus}} ion for free Gd{sup 3+} in model groundwater at pH 7-9. Rare earth element phosphate complexation is a significant process in natural freshwater systems which are neutral to mildly basic when the concentration ratio (HPO{sub 4}{sup 2{minus}})/(HCO{sub 3}{sup {minus}}) is greater than approximately 1 {times} 10{sup 3{minus}}.

• OSTI ID: 7114351
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 55:10; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GROUND WATER
ISOTOPIC EXCHANGE
PHOSPHATES
SORPTIVE PROPERTIES
RARE EARTHS
SORPTION
SEAWATER
CARBONATES
CERIUM 144
CHELATES
CHELATING AGENTS
CHEMICAL COMPOSITION
COMPLEXOMETRY
EQUILIBRIUM
FREE ENERGY
GADOLINIUM 153
GEOCHEMISTRY
ISOTOPE RATIO
LIGANDS
PARTIAL PRESSURE
PH VALUE
QUANTITY RATIO
RARE EARTH COMPLEXES
ROCK-FLUID INTERACTIONS
WATER CHEMISTRY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON COMPOUNDS
CERIUM ISOTOPES
CHEMISTRY
COMPLEXES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENERGY
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GADOLINIUM ISOTOPES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPES
METALS
NUCLEI
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
WATER
580000* - Geosciences