Vanadyl in natural waters: Adsorption and hydrolysis promote oxygenation

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90273-1· OSTI ID:7000936

Wehrli, B; Stumm, W ^[1]

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1. Swiss Institute of Technology, Zurich (Switzerland)

The aquatic chemistry of vanadium is dominated by V(IV) and V(V). Their species VO{sup 2+}, VO(OH){sup +} and H{sub 2}VO{sub 4}{sup {minus}}, HVO{sub 4}{sup 2{minus}}, respectively, occur primarily in natural waters. VO{sup 2+}, as a very hard Lewis acid, has a strong tendency to coordinate with oxygen donor atoms and is thus capable of both forming strong complexes with soluble organic chelates and becoming specifically adsorbed to particles, especially hydrous oxides. Vanadates (V), like phosphates, also have a tendency to form, by ligand exchange, surface complexes with hydrous oxides. The V(IV)-V(V) couple is an interesting redox sensor because the redox transitions occurs at E{sub H}-values typically often encountered at the sediment water interface; organic chelate formation may extend the redox boundary to E{sub H}-values of about +0.4V (pH 7-8), but in the presence of dissolved oxygen vanadate(V) prevails. Experimental data on the adsorption of VO{sup 2+} and of V(V) (HVO{sub 4}{sup 2{minus}}, VO{sub 2}{sup +}) on {delta}-Al{sub 2}O{sub 3} and TiO{sub 2} (anatase) surfaces provide evidence for strong specific adsorption. The interaction of VO{sup 2+} with oxide surfaces is interpreted in terms of inner-sphere bidentate surface complexes with the surface central metal ions of the oxide VO(OM<){sub 2}; vanadate and VO{sub 2}{sup +} form monodentate surface species. The rate of oxidation of VO{sup 2+} by oxygen is significantly enhanced by hydrolysis or adsorption to hydrous oxide surfaces. The rate law, derived earlier shows a first order dependence on the concentration of VO(OH){sup +} in homogeneous solution or on the concentration of the surface complex of VO(OM<){sub 2} in heterogeneous systems. A comparison with published data on Mn(II) and Fe(II) oxidation shows that coordinated OH-groups of solid surfaces are able, to mediate the electron transfer from the metal ions to the O{sub 2}-molecule.

• OSTI ID: 7000936
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:1; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
FRESH WATER
GEOCHEMISTRY
VANADIUM COMPOUNDS
ADSORPTION
CHEMICAL REACTION KINETICS
OXIDATION
REDOX POTENTIAL
SORPTIVE PROPERTIES
CHELATING AGENTS
CHEMICAL REACTIONS
COMBUSTION PRODUCTS
HYDROLYSIS
IONIC COMPOSITION
IRON IONS
LEWIS ACIDS
MANGANESE IONS
REDOX PROCESS
WATER CHEMISTRY
CHARGED PARTICLES
CHEMISTRY
DECOMPOSITION
HYDROGEN COMPOUNDS
INORGANIC ACIDS
IONS
KINETICS
LYSIS
OXYGEN COMPOUNDS
REACTION KINETICS
REPROCESSING
SEPARATION PROCESSES
SOLVOLYSIS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
WATER
580000* - Geosciences