A CHEMICAL AND PHOTOCHEMICAL STUDY OF RADICALIC SPECIES FORMED IN METHYLENE BLUE ACIDIC AND BASIC AQUEOUS SOLUTIONS

Electron spin resonance spectra have been used to gain information on the mechanism of photolysis of aqueous solution of methylene blue. The identity and behaviour of the semiquinone radicals formed as intermediate reduction products were discussed for strongly acid and for alkaline solutions. In order to obtain information on the photolytic mechanism in strongly acid media, irradiation was performed in the presence of various types of scavengers: D,L alanine, succinic acid, glucose, hydroquinone and sodium formate.