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RECORD NUMBER: 355 OF 501

OLS Field Name OLS Field Data
Main Title Photolysis of Copper(II)-Amino Acid Complexes in Water.
Author Hayase, K. ; Zepp., R. G. ;
CORP Author Environmental Research Lab., Athens, GA.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-91/176;
Stock Number PB91-231449
Additional Subjects Copper complexes ; Photolysis ; Amino acids ; Water pollution ; Ligands ; Toxicity ; Ultraviolet radiation ; Solar radiation ; Reduction(Chemistry) ; Photochemical reactions ; Reaction kinetics ; pH ; Reprints ;
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NTIS  PB91-231449 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 11/26/1991
Collation 8p
Abstract
Kinetics of the photolysis of Cu(+2)-amino acid complexes were investigated under sunlight or monochromatic radiation. Under sunlight (latitude 40 deg N) in the absence of dioxygen, the mean half-lives estimated for the photoreduction of the bis-Cu(+2) complexes (CuL2) 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 CuL2 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(+2)-beta-alanine and Cu(+2)-Tris complexes. Decreases in quantum yields observed with increasing acidity were attributed to changes in speciation from predominantly CuL2 to less photoreactive complexes, mainly CuL and Cu(+2). In air-saturated solutions, rates and quantum yields for Cu(I) formation were reduced sharply and hydrogen peroxide was formed. Results of the study suggest that photoreactions of Cu(+2) coordination complexes may contribute to its toxicity to aquatic biota.