Modelling the environmental degradation of water contaminants. Kinetics and mechanism of the riboflavin-sensitised-photooxidation of phenolic compounds

Photosensitized degradation in water of the phenolic pesticides bromoxynil and dichlorophen in the presence of riboflavin, as a model of their natural photodecomposition in the environment

“…stants 3 k q ( Table 1). The determined values of 1 k q and 3 k q for each PP are similar to those reported for phenol [16].…”

“…The rate constant 3 k q for the interaction of 3 Rf* with each PP was evaluated through a Stern-Volmer treatment. The laser flash photolysis apparatus and the methodology employed for the generation and detection of transient species have been described [16].…”

“…In the presence of Rf, it has been reported that the parent compound phenol and several substituted phenols can be efficiently degraded under visible irradiation, and that the photodegradation occurs mainly through radical-driven reactions, whereas in some cases O 2 ( 1 g )-mediated oxidations are also involved [15][16][17].…”

Photodecomposition of 4-chlorophenol by reactive oxygen species in UV/air system

“…(3)) [40][41][42][43]. It is commonly realized that in nature water, absorption of ultraviolet radiation by dissolved organic matter (DOM) generates an excited triplet state, which reacts with molecular oxygen to form superoxide radicalion [37,39].…”

Variation of sunstruck flavor-related substances in malted barley, triticale and spelt

“…Some authors [1,4,8,[18][19][20][21][22][23] described also the polyphenols such as catechin, epicatechin and quercitin, as protectors of the formation of this sunstruck flavor. The protective effect of polyphenols was described as (1) quenching both the singlet-and triplet-excited states of riboflavin with rates close to the diffusion control [22], (2) to preserve riboflavin absorbance in light-exposed model beers by quenching its excited energy state, and (3) a possible extraction of electrons by isohumulones from the polyphenols and the latter from photo-reduced riboflavin returning this to its original state [4].…”