title: Involvements of chloride ion in decolorization of Acid Orange 7 by activated peroxydisulfate or peroxymonosulfate oxidation.
abstract: The effects of chloride anion (Cl-) (up to 1.0 mol/L) on the decolorization of a model compound, azo dye Acid Orange 7 (AO7), by sulfate radical (SO4-*) based-peroxydisulfate (PS) or peroxymonosulfate (PMS) oxidation under various activated conditions (UV254 nm/PS, Thermal (70 degrees C/PS, UV254 nm/PMS, Co2+/PMS) were investigated. Methanol and NH4+ were used as quenching reagents to determine the contributions of active chlorine species (dichloride radical (Cl2-*) and hypochlorous acid (HClO)). The results indicated that the effects of Cl- on the reaction mechanism were different under various activated conditions. For UV/PS and Thermal/PS, the inhibition tendency became more clear as the Cl- concentration increased, probably due to the reaction between Cl- and SO4-* and the generation of Cl2-* or HCIO. For UV/PMS, Cl- did not exhibit inhibition when the concentration was below 0.1 mol/L. As Cl- concentration reached to 1.0 mol/L, the decolorization rate of AO7 was, however, accelerated, possibly because PMS directly reacts with Cl- to form HClO. For Co2+/PMS, Cl- exhibited a significant inhibiting effect even at low concentration (< or = 0.01 mol/L). When Cl- concentration exceeded 0.1 mol/L, the activation of PMS by Co2+ was almost completely inhibited. Under this condition, HClO maybe played a major role in decolorization of AO7. The results implicated that chloride ion is an important factor in SO4(-*) -based degradation of organic contamination in chloride-containing water.
authors.affiliation: Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Shiying
authors.initials: S
authors.lastname: Yang
authors.forename: Liang
authors.initials: L
authors.lastname: Shan
authors.forename: Rui
authors.initials: R
authors.lastname: Niu
authors.forename: Xueting
authors.initials: X
authors.lastname: Shao
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D006358:Hot Temperature; D006997:Hypochlorous Acid / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D014466:Ultraviolet Rays; D018508:Water Purification
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D002712:Chlorides; D005609:Free Radicals; D010545:Peroxides; D000644:Quaternary Ammonium Compounds; C038288:peroxymonosulfate; D006997:Hypochlorous Acid; C014722:2-naphthol orange; D000432:Methanol