title: Ozonation of azo dyes (Orange II and Acid Red 27) in saline media.
abstract: Ozonation of two azo dyes was investigated in a monitored bench scale bubble column reactor (8.5-L), varying liquid media salt content (0, 1, 40 and 100 g L(-1), NaCl). In experiments with Orange II pH was varied (5, 7.5 and 9) but ozonation of Acid Red 27 was performed at pH 7.5. Ozone self-decomposition rate-constant increased with salt concentration. Color removal was very effective and fast achieved under all experimental conditions. For the two azo dyes tested, more than 98% of color intensity was removed in 30-min ozonation assays. However, only partial mineralization of azo dyes (45%-Orange II; 20%-Acid Red 27) was attained in such experiments. The degree of mineralization (TOC removal) was negatively affected by salt concentration. Biodegradation assays conducted by respirometry revealed the inhibitory effect of dye degradation products formed during ozonation.
authors.affiliation: Chemical Engineering Program, COPPE, Federal University of Rio de Janeiro, CEP 21941-972 Rio de Janeiro, Brazil.
authors.forename: Alessandra C
authors.initials: AC
authors.lastname: Silva
authors.forename: Jean Stephane
authors.initials: JS
authors.lastname: Pic
authors.forename: Geraldo L
authors.initials: GL
authors.lastname: Sant'Anna
authors.forename: Marcia
authors.initials: M
authors.lastname: Dezotti
mesh_terms: D000548:Amaranth Dye; D001391:Azo Compounds / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry; D002244:Carbon; D004396:Coloring Agents / Q000737:chemistry*; D007220:Industrial Waste / Q000517:prevention & control*; D010126:Ozone / Q000737:chemistry*; D010865:Pilot Projects; D012965:Sodium Chloride; D013242:Sterilization; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D004396:Coloring Agents; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D010126:Ozone; D002244:Carbon; D000548:Amaranth Dye; C014722:2-naphthol orange