title: Kinetic analysis of C.I. Acid Yellow 9 photooxidative decolorization by UV-visible and chemometrics.
abstract: A kinetic study of the C.I. Acid Yellow 9 photooxidative decolorization process, using H(2)O(2) as oxidant, was carried out by chemometric analysis of the UV-visible data recorded during the process. The number of chemical species involved in the photooxidative decolorization process was established by singular value decomposition (SVD) and evolving factor analysis (EFA). Information about the different chemical species along the process was obtained from the spectral and concentration profiles recovered by soft multivariate curve resolution with alternating least squares (MCR-ALS). This information was complemented by mass spectrometry (MS) to postulate a reaction pathway. The dye photooxidative decolorization process involved consecutive and parallel reactions. The consecutive pathway consists of a first stage of dye oxidation followed by the rupture of the azo linkage to form smaller molecules that are degraded in a subsequent stage. The parallel reactions form products that are undetectable in the UV-visible spectra. Kinetic constants of the reactions postulated in the photooxidative process were retrieved by applying a hybrid hard and soft MCR-ALS resolution. All constants were similar for the consecutive stages and higher than those obtained for the parallel reactions.
authors.affiliation: Department of Analytical and Organic Chemistry, Rovira i Virgili University, C/Marcel·lí Domingo, s/n, Campus Sescelades, E-43007 Tarragona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernández
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Callao
authors.forename: M Soledad
authors.initials: MS
authors.lastname: Larrechi
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D004396:Coloring Agents / Q000737:chemistry* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D010083:Oxidants, Photochemical / Q000737:chemistry*; D055668:Photochemical Processes
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D010083:Oxidants, Photochemical; D006861:Hydrogen Peroxide; C561341:C.I. acid yellow 9