Salt effect on sensitized photooxidations. A kinetic approch to environmental decomposition of marine contaminants
M.I. Gutiérrez, S. Criado and N.A. García

The salt effect on the kinetics of singlet molecular oxygen [O2(1Dg)]-mediated photooxidations of sea water contaminants was investigated. Two families of photooxidizable compounds were employed in the study: anthracene derivatives and phenols. The presence of salt (NaCl in H2O and LiCl in MeCN, in both cases in the range 0-0.45 M) produces changes in the photooxidation rate. For solvent-polarity-dependent reactions, this behavior can be predicted, by knowing the solvent-polarity dependence of the rate constant for chemical reaction of the substrates with O2(1Dg) in non-saline solutions (kr). For the cases of photooxidations possessing solvent-polarity-independent or scantily-dependent kr values, the photooxidation rates decrease as the salt content in the solution increases, mainly due to a predominance of the physical quenching pathway. In addition, the quantum yield for O2(1Dg) generation (FD) was determined in a series of saline solutions, in the range of 0-0.45 M in water and MeCN solutions, in the presence of NaCl and LiCl respectively. The D values are independent, within the experimental error on the salt content.

Contents of this volume Sci. Mar. 62(3) : 217-223 Back PDF
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