title: Decomposition pathways and reaction intermediate formation of the purified, hydrolyzed azo reactive dye C.I. Reactive Red 120 during ozonation.
abstract: In this study, an aqueous solution of purified, hydrolyzed C.I. Reactive Red 120 (RR 120, Color Index), was selected as a model to investigate the degradation pathways and to obtain additional information on the reaction intermediate formation. The dye was purified to avoid the influence of the impurities on the ozonation process and on the formation of oxidation by-products. To simulate the dye-bath effluents from dyeing processes with azo reactive dyes, a hydrolyzed form of the dye was chosen as a representative compound. High performance liquid chromatography/mass spectrometry and its tandem mass spectrometry was chosen to identify the decomposition pathways and reaction intermediate formation during the ozonation process. In addition total organic carbon and high performance ion chromatography analysis were employed to obtain further information on the reaction processes during ozonation. Purified, hydrolyzed RR 120 was decomposed under the direct nucleophilic attack by ozone resulting in oxidation and cleavage of azo group and aromatic ring, while the triazine group still remained in the solution even after prolonged oxidation time (120 min) due to its high resistance to ozonation. Phenol, 1,2-dihydroxysulfobezene, 1-hydroxysulfonbezene were detected as the degradation intermediates, which were further oxidized by O(3) and *OH to other open-ring products and then eventually led to simple oxalic and formic acid identified by HPIC.
authors.affiliation: GSF-National Research Center for Environment and Health GmbH, Institute of Ecological Chemistry, D-85764 Neuherberg, Germany.
authors.forename: Feifang
authors.initials: F
authors.lastname: Zhang
authors.forename: Ayfer
authors.initials: A
authors.lastname: Yediler
authors.forename: Xinmiao
authors.initials: X
authors.lastname: Liang
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents / Q000737:chemistry*; D006868:Hydrolysis; D007220:Industrial Waste / Q000032:analysis; D010126:Ozone / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013783:Textile Industry; D014227:Triazines / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D007220:Industrial Waste; D014227:Triazines; C042516:reactive red 120 dye; D010126:Ozone