Photolysis of copper(II)-amino acid complexes in water

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00019a007· OSTI ID:5328301

Hayase, K; Zepp, R G ^[1]

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1. Environmental Protection Agency, Athens, GA (United States)

Kinetics of the photolysis of Cu{sup 2+}-amino acid complexes were investigated under sunlight or monochromatic radiation. Under sunlight (latitude 40{degree}N) in the absence of dioxygen, the mean half-lives estimated for the photoreduction of the bis-Cu{sup 2+} complexes (CuL{sub 2}) at pH 8.0 and 25C were 0.55, 1.6, 8.6, 8.8, 45. and 71 days for L = tris(hydroxymethyl)aminomethane (Tris), {beta}-alanine, L-aspartic acid, L-glutamic acid, glycine, and histidine, respectively. Under monochromatic UV irradiation (310 nm) with dioxygen absent, quantum yields for the photoproduction of Cu(I) from CuL{sub 2} were found to be 0.071, 0.098, 0.063, 0.066, 0.025, and 0.0011 for L = Tris, {beta}-alanine, L-aspartic acid, L-glutamic acid, glycine, and L-histidine, respectively. The effects of pH on the quantum yields were determined for Cu{sup 2+}-{beta}-alanine and Cu{sup 2+}-Tris complexes. Decreases in quantum yields observed with increasing acidity were attributed to changes in speciation from predominantly CuL{sub 2} to less photoreactive complexes, mainly CuL and Cu{sup 2+}. In air-saturated solutions, rates and quantum yields for Cu(I) formation were sharply reduced and hydrogen peroxide was formed. Results of the study suggest that photoreactions of Cu{sup 2+} coordination complexes may contribute to its toxicity to aquatic biota.

• OSTI ID: 5328301
• Journal Information: Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 25:7; ISSN ESTHA; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
54 ENVIRONMENTAL SCIENCES
540310 -- Environment
Aquatic-- Basic Studies-- (1990-)
AMINO ACIDS
AQUATIC ECOSYSTEMS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
COMPLEXES
COPPER COMPOUNDS
DATA
DECOMPOSITION
ECOSYSTEMS
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
INFORMATION
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PH VALUE
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATIONS
SOLAR RADIATION
STELLAR RADIATION
TOXICITY
TRANSITION ELEMENT COMPOUNDS
ULTRAVIOLET RADIATION
VALENCE