Photodegradation of CI Acid Orange 60 and CI Acid Green 25 in an Amide Environment

Abstract

Photodegradation, in solution and in nylon 66 fiber, of two automotive acid dyes (CI acid orange 60 and CI acid green 25) for nylon carpet has been investigated. Photofading in solution was done in dimethylformamide (DMF) with the aid of a 254-nm light source, and the work in nylon fiber used the xenon arc light of an Atlas CI 65 weatherometer. The results show that these dyes fade via a photoreduction process under both sets of conditions, and they suggest that DMF is a suitable model for nylon in characterizing the photodegradation of acid dyes. The structures of the degradation products of the two dyes were determined with the aid of fast atom bom bardment and desorption chemical ionization mass spectrometry and by HPLC and TLC comparisons with authentic samples.