title: Activated carbon catalyzed persulfate oxidation of Azo dye acid orange 7 at ambient temperature.
abstract: Persulfate (PS) oxidative degradation of azo dye acid orange 7 (AO7) in an aqueous solution was studied in the presence of suspended granular activated carbon (GAC) at ambient temperature (e.g., 25°C). It was observed that there existed a remarkable synergistic effect in the GAC/PS combined system. Higher PS concentration and GAC dosage resulted in higher AO7 degrading rates. Near-neutral was the optimal initial pH. Adsorption had an adverse effect on AO7 degradation. AO7 had not only a good decolorization, but a good mineralization. The decomposition of PS followed a first-order kinetics behavior both in the presence and in the absence of AO7. Radical mechanism was studied and three radical scavengers (methanol (MA), tert-butanol (TBA), phenol) were used to determine the kind of major active species taking part in the degradation of AO7 and the location of degradation reaction. It was assumed that the degradation of AO7 did not occur in the liquid phase, but in the porous bulk and boundary layer on the external surface of GAC. SO(4)(-•) or HO•, generated on or near the surface of GAC, played a major role in the AO7 degradation. Finally, the recovery performance of GAC was studied through the GAC reuse experiments.
authors.affiliation: Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, China. shiningpup@hotmail.com
authors.forename: Shiying
authors.initials: S
authors.lastname: Yang
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Xueting
authors.initials: X
authors.lastname: Shao
authors.forename: Rui
authors.initials: R
authors.lastname: Niu
authors.forename: Leilei
authors.initials: L
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D005609:Free Radicals / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013464:Sulfuric Acids / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D005609:Free Radicals; D013464:Sulfuric Acids; D002244:Carbon; C014722:2-naphthol orange