Rose bengal-sensitized photooxygenation of chlorohydroxyaromatic contaminants in water: A kinetic study

PAJARES, ADRIANA; STETTLER, GUILLERMO; GIANOTTI, JOSÉ; BUSTOS, SILVIA; CRIADO, SUSANA; GARCÍA, NORMAN A.

TOXICOLOGICAL AND ENVIRONMENTAL CHEMISTRY (PRINT)

Taylor and Francis Ltd.

Lugar: Bayreuth; Año: 1996 vol. 54 p. 115 - 124

0277-2248

A kinetic study of the RB-sensitized photooxygenation of a series of chlorohydroxyaromatic (ClArOH) water contaminants (phenolic and dihydroxybenzene derivatives) has been carried out. In addition, an exhaustive study on the possible interactions of RB electronically excited triplet and singlet states with CIArOH was also developed. The determination of relative rates of oxygen uptake upon sensitized irradiation, employing auxiliar selective quenchers of oxygen active species, indicate the contribution of both singlet molecular oxygen (ca. 71%) and Superoxide ion (ca. 26%) as the reactive pathways for CIArOH degradation. The substitution by chlorine atoms in position meta greatly decrease the photooxygenation rate of the phenolic derivatives. For the dihydroxybenzene series, increase in nuclear chlorination parallels a decrease in the photodegradation rate. Outdoors sensitized solar irradiation experiments on different CIArOH mixtures leads to measurable levels of oxygen after a few minutes exposure. From the environmental point of view, and ruling out the possibility of direct-irradiation photoreactions, sensitized photooxygenation appears as an alternative pathway for CIArOH degradation, in competence with other naturally-occurring photoprocesses involving reactive transient species.