Slow coordination reactions in aquatic systems

Conference · Thu Sep 01 04:00:00 EDT 1988 · Preprints of Papers Presented at National Meeting, Division of Water, Air and Waste Chemistry, American Chemical Society; (USA)

OSTI ID:7019343

Hering, J G; Morel, F M.M. ^[1]

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1. Massachusetts Institute of Technology, Cambridge (USA)

The rates of reaction of transition metals with free (or protonated) lignds are intrinsically fast. Yet the observed rate of formation of metal complexes with strong ligands in seawater systems containing a mixture of ligands is remarkably slow. When copper is added to mixtures of natural and synthetic ligands, the equilibrium distribution of metal species is only established after hours or even days. At the calcium concentration of seawater, kinetic hindrance to the initial reaction of the stronger ligand with the added metal results in initial formation of copper complexes with the weaker ligands. Equilibrium metal speciation is attained slowly through a series of ligand and metal exchange reactions. Observations of slow kinetics of coordination reactions in model systems demonstrate that re-equilibration of a natural system undergoing perturbations of metal or ligand concentrations cannot be assumed to be rapid. This study also suggests that the concentration of strong complexing agents in seawater may be underestimated in measurements of metal complexation that involve metal additions.

• OSTI ID: 7019343
• Report Number(s): CONF-8809264--
• Conference Information: Journal Name: Preprints of Papers Presented at National Meeting, Division of Water, Air and Waste Chemistry, American Chemical Society; (USA) Journal Volume: 28:2
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHEMISTRY
COMPLEXES
COPPER COMPLEXES
HYDROGEN COMPOUNDS
LIGANDS
OXYGEN COMPOUNDS
SEAWATER
TRANSITION ELEMENT COMPLEXES
WATER
WATER CHEMISTRY